Circular Motion PPP

Circular Motion described, using The Physics Classroom for animations and diagrams.

1. Characteristics of Characteristics of
Circular MotionCircular Motion
Q&A using animations and questions from Q&A using animations and questions from The Physics Classroom atThe Physics Classroom at
http://www.glenbrook.k12.il.us/gbssci/phys/Class/circles/u6l1c.htmlhttp://www.glenbrook.k12.il.us/gbssci/phys/Class/circles/u6l1c.html

2. Acceleration Characteristics for Acceleration Characteristics for
Circular MotionCircular Motion
An object moving in uniform circular An object moving in uniform circular
motion is moving in a circle with a motion is moving in a circle with a
uniform or constant speed. uniform or constant speed.

3. Explain why there is acceleration in Explain why there is acceleration in
circular motion if the SPEED is circular motion if the SPEED is
Constant.Constant.
An accelerating object is an object which is An accelerating object is an object which is
changing its velocity. changing its velocity.
Since velocity is a vector which has both Since velocity is a vector which has both
magnitude and direction, a change in either the magnitude and direction, a change in either the
magnitude or the direction constitutes a change in magnitude or the direction constitutes a change in
the velocity. the velocity.
For this reason, it can be boldly declared that an For this reason, it can be boldly declared that an
object moving in a circle at constant speed is object moving in a circle at constant speed is
indeed accelerating. indeed accelerating.
It is accelerating because its velocity is changing It is accelerating because its velocity is changing
its directions.its directions.

4.   In which direction does the velocity In which direction does the velocity
change (Acceleration) vector point?change (Acceleration) vector point?
The velocity change vector is directed The velocity change vector is directed
towards the center. towards the center.
An object moving in a circle at a constant An object moving in a circle at a constant
speed from A to B experiences a velocity speed from A to B experiences a velocity
change and therefore an acceleration.change and therefore an acceleration.
This acceleration is directed towards the This acceleration is directed towards the
center of the circlecenter of the circle..

5. Briefly explain why, using Briefly explain why, using
geometric proof.geometric proof.
In this time, the velocity has changed from In this time, the velocity has changed from vv
ii to to vv
ff. The process of . The process of
subtracting subtracting vv
ii from from vv
ff is shown in the vector diagram; this process is shown in the vector diagram; this process
yields the change in velocity.yields the change in velocity.

There is a velocity change for an object moving in a circle with a There is a velocity change for an object moving in a circle with a
constant speed. constant speed.

Note that this velocity change vector is directed towards the center. Note that this velocity change vector is directed towards the center.
•In the case of an object
moving in a circle about
point C, the object has
moved from point A to
point B.

6. Give two real world demonstrations of Give two real world demonstrations of
this inward acceleration. this inward acceleration.
If a glass with a lit candle is held at the If a glass with a lit candle is held at the
end of an outstretched arm as you spin end of an outstretched arm as you spin
in a circle at a constant rate (such that in a circle at a constant rate (such that
the flame experiences an acceleration), the flame experiences an acceleration),
then the candle flame will no longer then the candle flame will no longer
extend vertically upwards. extend vertically upwards.
Instead the flame deflects from its Instead the flame deflects from its
upright position, signifying that there is upright position, signifying that there is
an acceleration when the flame moves an acceleration when the flame moves
in a circular path at constant speed. in a circular path at constant speed.
The deflection of the flame will be in The deflection of the flame will be in
the direction of the acceleration. the direction of the acceleration.
When you do this experiment, you find When you do this experiment, you find
that the flame deflects towards the that the flame deflects towards the
center of the circle, thus indicating that center of the circle, thus indicating that
not only is there an acceleration; but not only is there an acceleration; but
that there is an inward acceleration.that there is an inward acceleration.

7. Give two real world demonstrations of Give two real world demonstrations of
this inward acceleration. this inward acceleration.
a.a. Use a cork accelerometer (a cork Use a cork accelerometer (a cork
submerged in a sealed flask of water) held in an submerged in a sealed flask of water) held in an
outstretched arm and move in a circle at a outstretched arm and move in a circle at a
constant rate of turning. constant rate of turning.
As the cork-water combination spun in the circle, As the cork-water combination spun in the circle,
the cork leaned towards the center of the circle. the cork leaned towards the center of the circle.
Once more, there is proof that an object moving Once more, there is proof that an object moving
in circular motion at constant speed experiences in circular motion at constant speed experiences
an acceleration which directed towards the center an acceleration which directed towards the center
of the circle.of the circle.

8. Do the Do the “C“Check Your Understandingheck Your Understanding” ” #1-#1-
8 on the site.8 on the site.
Go to the website to use the Go to the website to use the
interactive questions.interactive questions.

9. An object moving in a circle is An object moving in a circle is
experiencing acceleration. Even if experiencing acceleration. Even if
moving around the perimeter of moving around the perimeter of
the circle with a constant speed, the circle with a constant speed,
there is still a change in velocity there is still a change in velocity
and subsequently an and subsequently an
acceleration. acceleration.
This acceleration is directed This acceleration is directed
TOWARDS THE CENTER of the TOWARDS THE CENTER of the
circle. circle.

10. Newton's second law of motionNewton's second law of motion
says that … says that …
an object which experiences an an object which experiences an
acceleration must also be acceleration must also be
experiencing a net forceexperiencing a net force
the direction of the net force is in the direction of the net force is in
the same direction as the the same direction as the
acceleration. acceleration.

11. So for an object moving So for an object moving
in a circle, there must be in a circle, there must be
an inward force an inward force acting acting
upon it in order to cause upon it in order to cause
its inward acceleration.its inward acceleration.

12. This is sometimes This is sometimes
referred to as the referred to as the
CENTRIPETAL FORCE CENTRIPETAL FORCE
REQUIREMENT. REQUIREMENT.

13. The word "centripetal" The word "centripetal"
means CENTER-SEEKING. means CENTER-SEEKING.
For objects moving in For objects moving in
circular motion, there is a circular motion, there is a
net force acting towards the net force acting towards the
center which causes the center which causes the
object to object to seekseek the center. the center.

14. Newton's first law of motionNewton's first law of motion - - the law of the law of
inertia inertia states that….states that….
"... objects in motion tend to stay "... objects in motion tend to stay
in motion with the same speed in motion with the same speed
and the same direction unless and the same direction unless
acted upon by an unbalanced acted upon by an unbalanced
force."force."

15. Objects will tend to naturally Objects will tend to naturally
travel in straight lines; an travel in straight lines; an
unbalanced force is required unbalanced force is required
to cause it to turn. The to cause it to turn. The
presence of THE presence of THE
UNBALANCED FORCE is UNBALANCED FORCE is
required for objects to move required for objects to move
in circles.in circles.

16. There is an outward force and an There is an outward force and an
outward acceleration acting on your outward acceleration acting on your
body when you sit in the passenger body when you sit in the passenger
seat of a car making a left hand turn. seat of a car making a left hand turn.
True or False?True or False?

17. Explain your answer. Explain your answer.
It is the inertia of your body - the It is the inertia of your body - the
tendency to resist acceleration - which tendency to resist acceleration - which
causes it to continue in its forward causes it to continue in its forward
motion. motion.
While the car is accelerating inward, While the car is accelerating inward,
you continue in a straight line. you continue in a straight line.
If you are sitting on the passenger If you are sitting on the passenger
side of the car, then eventually the side of the car, then eventually the
outside door of the car will hit you as outside door of the car will hit you as
the car turns inward. the car turns inward.
In reality, you are continuing in your In reality, you are continuing in your
straight-line inertial path tangent to straight-line inertial path tangent to
the circle while the car is accelerating the circle while the car is accelerating
out from under you. out from under you.

18. The sensation of an outward force The sensation of an outward force
and an outward acceleration is a and an outward acceleration is a
false sensation. false sensation.
There is no physical object There is no physical object
capable of pushing you outwards. capable of pushing you outwards.
You are merely experiencing the You are merely experiencing the
tendency of your body to continue tendency of your body to continue
in its path tangent to the circular in its path tangent to the circular
path along which the car is path along which the car is
turning.turning.

19. What is a What is a centripetal forcecentripetal force? ?
Some physical force pushing or Some physical force pushing or
pulling the object towards the pulling the object towards the
center of the circle. center of the circle.
The word "centripetal" is merely The word "centripetal" is merely
an adjective used to describe the an adjective used to describe the
direction of the force. direction of the force.

20. Is centripetal force a new type Is centripetal force a new type
of force? of force?
Yes or NoYes or No??
NO! NO!
We are not introducing a new We are not introducing a new typetype of of
force but rather describing the force but rather describing the
direction of the net force acting upon direction of the net force acting upon
the object which moves in the circle. the object which moves in the circle.
Whatever the object, if it moves in a Whatever the object, if it moves in a
circle, there is some force acting upon circle, there is some force acting upon
it to cause it to deviate from its it to cause it to deviate from its
straight-line path, accelerate inwards straight-line path, accelerate inwards
and move along a circular path. and move along a circular path.

21. Give three examples of Give three examples of
centripetal force. centripetal force.
As a car makes a turn, the force of As a car makes a turn, the force of
friction acting upon the turned wheels friction acting upon the turned wheels
of the car provide the centripetal force of the car provide the centripetal force
required for circular motion.required for circular motion.

22. Give three examples of Give three examples of
centripetal force. centripetal force.
As a bucket of water is tied to a As a bucket of water is tied to a
string and spun in a circle, the string and spun in a circle, the
force of tension acting upon the force of tension acting upon the
bucket provides the centripetal bucket provides the centripetal
force required for circular motion.force required for circular motion.

23. Give three examples of Give three examples of
centripetal force.centripetal force.
As the moon orbits the Earth, the As the moon orbits the Earth, the
force of gravity acting upon the force of gravity acting upon the
moon provides the centripetal moon provides the centripetal
force required for circular motion.force required for circular motion.

24. The centripetal force for uniform The centripetal force for uniform
circular motion alters the circular motion alters the
direction of the object without direction of the object without
altering its speed. altering its speed.
True or False?True or False?

25. Here’s the situation:Here’s the situation:
You are You are carrying a tennis carrying a tennis
ball upon a flat, level board. ball upon a flat, level board.
Once the tennis ball and the Once the tennis ball and the
board are in motion, they board are in motion, they
will continue in motion in the will continue in motion in the
same direction at the same same direction at the same
speed unless acted upon by speed unless acted upon by
an unbalanced force. an unbalanced force.
This is in accord with This is in accord with
Newton's first law of motion. Newton's first law of motion.

26. Here’s the question:Here’s the question:
If you apply an unbalanced If you apply an unbalanced
force to the flat board, then force to the flat board, then
the flat board will accelerate. the flat board will accelerate.
If the force is continually If the force is continually
directed towards a point at the directed towards a point at the
center of the circle, then the center of the circle, then the
flat board will round the corner flat board will round the corner
in a circular-like path. in a circular-like path.
What will happen to the ball as What will happen to the ball as
the flat board is moved in a the flat board is moved in a
circle?circle?

27. The answer: The answer:
Go to the animation at this site. Go to the animation at this site.
View the animation on the LEFT side View the animation on the LEFT side
of the page.of the page.
http://www.glenbrook.k12.il.us/gbssci/phys/mmedia/circmot/cf.htmlhttp://www.glenbrook.k12.il.us/gbssci/phys/mmedia/circmot/cf.html . .

28. An altered situation: An altered situation:
Now a block is secured to Now a block is secured to
the board in such a manner the board in such a manner
that the block applies an that the block applies an
unbalanced force to the unbalanced force to the
ball that is directed ball that is directed
towards the center of the towards the center of the
circle.circle.
The block provides a The block provides a
normal force directed normal force directed
inward. inward.
What will happen to the What will happen to the
ball as the flat board is ball as the flat board is
moved in a circle?moved in a circle?

29. The Answer: The Answer:
Go to the animation at this site. Go to the animation at this site.
View the animation on the LEFT side View the animation on the LEFT side
of the page. of the page.
http://www.glenbrook.k12.il.us/gbssci/phys/mmedia/circmot/cf.htmlhttp://www.glenbrook.k12.il.us/gbssci/phys/mmedia/circmot/cf.html

30. Circular MotionCircular Motion
Centripetal: “towards the center”.Centripetal: “towards the center”.
Radial: Along the radius of a circle.Radial: Along the radius of a circle.
Centripetal is often used interchangeably Centripetal is often used interchangeably
with radial.with radial.

31. Circular MotionCircular Motion vs. vs. Linear MotionLinear Motion
Moving around a Moving around a
fixed point fixed point
remaining the remaining the
same distance same distance
from that point at from that point at
all times.all times.
Moving in a Moving in a
straight line away straight line away
from a fixed point, from a fixed point,
increasing the increasing the
distance from that distance from that
point at all times.point at all times.

32. AXESAXES
Circular MotionCircular Motion vs. vs. Linear MotionLinear Motion
Radial axis which Radial axis which
points to the points to the
center of the circle.center of the circle.
Tangential axis Tangential axis
which points in the which points in the
direction of motion.direction of motion.
Depending on point Depending on point
of view, a y-axis of view, a y-axis
may be used as may be used as
well.well.
X-axis which X-axis which
usually points usually points
horizontally.horizontally.
Y-axis which Y-axis which
usually points usually points
vertically.vertically.

33. ACCELERATIONACCELERATION
Circular MotionCircular Motion vs. vs. Linear MotionLinear Motion
Radial Acceleration Radial Acceleration
always points to always points to
the center of the the center of the
circle.circle.
Tangential Tangential
Acceleration Acceleration
depends on depends on
whether velocity is whether velocity is
increasing, increasing,
decreasing or decreasing or
constant.constant.
X-axis acceleration X-axis acceleration
depends on whether depends on whether
velocity is increasing, velocity is increasing,
decreasing or decreasing or
constant.constant.
Y-axis acceleration Y-axis acceleration
depends on whether depends on whether
velocity is increasing, velocity is increasing,
decreasing or decreasing or
constant.constant.
Acceleration on one of Acceleration on one of
the axes is always the axes is always
zero.zero.

34. FORCESFORCES
Circular MotionCircular Motion vs. vs. Linear MotionLinear Motion
There MUST be There MUST be
at least one at least one
force pointing force pointing
towards the towards the
center of the center of the
circular path.circular path.
WHY?WHY?
•Since there is always Since there is always
centripetal acceleration, centripetal acceleration,
there must be a there must be a
centripetal force. centripetal force.
•WHO said that?WHO said that?
Newton (his second Newton (his second
law)law)
There can be There can be
forces in any forces in any
direction.direction.
There must be a There must be a
force pointing in force pointing in
the direction of the direction of
acceleration.acceleration.

35. IMPORTANT NOTEIMPORTANT NOTE
An object WILL NOT move in a An object WILL NOT move in a
circular path unless there is a circular path unless there is a
force acting on the radial axis force acting on the radial axis
pointing in towards the center pointing in towards the center
of the circle.of the circle.

36. In which direction will the object In which direction will the object
move without the centripetal force?move without the centripetal force?
Along the tangential axisAlong the tangential axis
In the direction of motionIn the direction of motion
In a straight line.In a straight line.

37. MOTION DIAGRAMSMOTION DIAGRAMS
Circular MotionCircular Motion vs. vs. Linear MotionLinear Motion
On the radial axis, On the radial axis,
motion diagrams motion diagrams
only consist of the only consist of the
acceleration and acceleration and
net force direction; net force direction;
velocity is not velocity is not
needed.needed.
On the tangential On the tangential
or y-axis, motion or y-axis, motion
diagrams are diagrams are
normal, if needed.normal, if needed.
Draw velocity and Draw velocity and
acceleration arrows acceleration arrows
to represent to represent
increasing, increasing,
decreasing or decreasing or
constant speed.constant speed.

38. FREE BODY DIAGRAMSFREE BODY DIAGRAMS
Circular MotionCircular Motion vs. vs. Linear MotionLinear Motion
Draw forces the same Draw forces the same
as always.as always.
Make sure there is a Make sure there is a
force on the radial axis force on the radial axis
pointing towards the pointing towards the
center of the circle.center of the circle.
Axes must include the Axes must include the
radial (positive radial (positive
towards the center) towards the center)
and either tangential and either tangential
or y-axis.or y-axis.
Forces are Forces are
represented with represented with
arrows pointing in arrows pointing in
the direction of the the direction of the
push or pull.push or pull.
X- and y-axes X- and y-axes
point in the point in the
direction of the direction of the
most forces, most forces,
usually with x in usually with x in
the direction of the direction of
motion.motion.

39. EquationsEquations
Circular MotionCircular Motion vs. vs. Linear MotionLinear Motion
Newton’s Second Newton’s Second
Law: Law:
F = maF = ma
Acceleration: Acceleration:
a = va = v
22
/R/R
Newton’s Second Newton’s Second
Law: Law:
F = maF = ma
Acceleration: Acceleration:
a = (va = (v
ff
– v – v
oo
)/t)/t
(You will recognize this (You will recognize this
equation as vequation as v
ff = v = v
00 + at) + at)

40. WHAT IS A CENTRIFUGAL WHAT IS A CENTRIFUGAL
FORCE?FORCE?
Centrifugal forces are a MYTH! They Centrifugal forces are a MYTH! They
do not really exist.do not really exist.
It is the effect of Newton’s First Law It is the effect of Newton’s First Law
acting on an object while the object acting on an object while the object
is being moved in a circular path.is being moved in a circular path.

41. What are three mathematical quantities What are three mathematical quantities
which will be of primary interest to us?which will be of primary interest to us?
force, speed, and acceleration.force, speed, and acceleration.

42. Velocity is determined using the Velocity is determined using the
equationequation

43. The acceleration of an object moving in The acceleration of an object moving in
a circle can be determined by the a circle can be determined by the
equationsequations  

44. The net force is related to the acceleration of The net force is related to the acceleration of
the object (as is always the case) and is given the object (as is always the case) and is given
by the equationsby the equations

45. This set of circular motion equations This set of circular motion equations
can be used in two ways:can be used in two ways:
a.a. as a as a recipe for algebraic problem solving recipe for algebraic problem solving in order in order
to solve for an unknown quantity. to solve for an unknown quantity.
b.b. as a "guide to thinking" about as a "guide to thinking" about how an how an
alteration in one quantity would effect alteration in one quantity would effect
a second quantitya second quantity
..

46. How can the equations for circular How can the equations for circular
motion be used as a guide to motion be used as a guide to
thinking? thinking? 
the equation relating the net force the equation relating the net force
((FF
netnet
) to the speed () to the speed (vv) of an object ) of an object
moving in uniform circular motion is Fmoving in uniform circular motion is F
netnet
= mv= mv
22
/R/R
This equation shows that the net force This equation shows that the net force
required for an object to move in a required for an object to move in a
circle is directly proportional to the circle is directly proportional to the
square of the speed of the object. For square of the speed of the object. For
a constant mass and radius, the a constant mass and radius, the FF
netnet is is
proportional to the proportional to the speedspeed
22
..

47. The factor by which the net force The factor by which the net force
is altered is the square of the is altered is the square of the
factor by which the speed is factor by which the speed is
altered. Subsequently, if the altered. Subsequently, if the
speed of the object is doubled, speed of the object is doubled,
the net force required for that the net force required for that
object's circular motion is object's circular motion is
quadrupled. And if the speed of quadrupled. And if the speed of
the object is halved (decreased by the object is halved (decreased by
a factor of 2), the net force a factor of 2), the net force
required is decreased by a factor required is decreased by a factor
of 4.of 4.

48. The process of solving a circular The process of solving a circular
motion problem is much like any other motion problem is much like any other
problem in physics class. problem in physics class.
The process involves:The process involves:
• a careful reading of the problema careful reading of the problem
•the identification of the known and the identification of the known and
required information in variable formrequired information in variable form
•the selection of the relevant equation(s)the selection of the relevant equation(s)
•substitution of known values into the substitution of known values into the
equationequation
•finally algebraic manipulation of the finally algebraic manipulation of the
equation to determine the answer equation to determine the answer

49. A 900-kg car moving at 10 m/s takes a turn A 900-kg car moving at 10 m/s takes a turn
around a circle with a radius of 25.0 m. around a circle with a radius of 25.0 m.
Determine the acceleration and the net force Determine the acceleration and the net force
acting upon the car.acting upon the car.
To determine the acceleration of the car, use To determine the acceleration of the car, use
the equation a = (vthe equation a = (v
22
)/R. The solution is as )/R. The solution is as
follows:follows:
a = (va = (v
22
)/R a = ((10.0 m/s))/R a = ((10.0 m/s)
22
)/(25.0 m))/(25.0 m)
a = (100 ma = (100 m
22
/s/s
22
)/(25.0 m))/(25.0 m)
a = 4 m/sa = 4 m/s
22
To determine the net force acting upon the To determine the net force acting upon the
car, use the equation Fnet = m*a. The car, use the equation Fnet = m*a. The
solution is as follows.solution is as follows.
FF
netnet
= m*a F = m*a F
netnet
= (900 kg)*(4 m/s = (900 kg)*(4 m/s
22
))
FF
netnet = 3600 N = 3600 N

50. A 95-kg halfback makes a turn on the football field. The halfback A 95-kg halfback makes a turn on the football field. The halfback
sweeps out a path which is a portion of a circle with a radius of 12-sweeps out a path which is a portion of a circle with a radius of 12-
meters. The halfback makes a quarter of a turn around the circle in meters. The halfback makes a quarter of a turn around the circle in
2.1 seconds. Determine the speed of the halfback.2.1 seconds. Determine the speed of the halfback.  
To determine the speed of the To determine the speed of the
halfback, use the equation v = d/t halfback, use the equation v = d/t
where the d is one-fourth of the where the d is one-fourth of the
circumference and the time is 2.1 s. circumference and the time is 2.1 s.
The solution is as follows:The solution is as follows:
v = d/t v = (0.25 * 2 * pi * R)/tv = d/t v = (0.25 * 2 * pi * R)/t
v = (0.25 * 2 * 3.14 * 12.0 m)/(2.1 s)v = (0.25 * 2 * 3.14 * 12.0 m)/(2.1 s)
v = 8.97 m/sv = 8.97 m/s

51. A 95-kg halfback makes a turn on the football field. The halfback A 95-kg halfback makes a turn on the football field. The halfback
sweeps out a path which is a portion of a circle with a radius of sweeps out a path which is a portion of a circle with a radius of
12-meters. The halfback makes a quarter of a turn around the 12-meters. The halfback makes a quarter of a turn around the
circle in 2.1 seconds. Determine the acceleration of and net force circle in 2.1 seconds. Determine the acceleration of and net force
acting upon the halfback.acting upon the halfback.  
To determine the acceleration of the To determine the acceleration of the
halfback, use the equation a = (vhalfback, use the equation a = (v
22
)/R. The )/R. The
solution is as follows:solution is as follows:
a = (va = (v
22
)/R a = ((8.97 m/s))/R a = ((8.97 m/s)
22
)/(12.0 m))/(12.0 m)
a = (80.5 ma = (80.5 m
22
/s/s
22
)/(12.0 m))/(12.0 m)
a = 6.71 m/sa = 6.71 m/s
22
To determine the net force acting upon the To determine the net force acting upon the
halfback, use the equation Fnet = m*a. The halfback, use the equation Fnet = m*a. The
solution is as follows.solution is as follows.
FF
netnet
= m*a F = m*a F
netnet
= (95.0 kg)*(6.71 m/s = (95.0 kg)*(6.71 m/s
22
))
FF
netnet
= 637 = 637 N N

52. Anna fills a bucket with water, ties it to a strong rope, and Anna fills a bucket with water, ties it to a strong rope, and
spins it in a circle. Anna spins the bucket when it is half-full spins it in a circle. Anna spins the bucket when it is half-full
of water and when it is quarter-full of water. In which case of water and when it is quarter-full of water. In which case
is more force required to spin the bucket in a circle? is more force required to spin the bucket in a circle?
Answer the question and then check Answer the question and then check
at The Physics Classroom!at The Physics Classroom!

53. A Lincoln Continental and a Yugo are making a turn. The A Lincoln Continental and a Yugo are making a turn. The
Lincoln is four times more massive than the Yugo. If they Lincoln is four times more massive than the Yugo. If they
make the turn at the same speed, then how do the make the turn at the same speed, then how do the
centripetal forces acting upon the two cars compare. centripetal forces acting upon the two cars compare.
Explain.Explain.
Answer the question and then check Answer the question and then check
at The Physics Classroom!at The Physics Classroom!

54. The Gravitron at Six Flags is a ride in which occupants line The Gravitron at Six Flags is a ride in which occupants line
the perimeter of a cylinder and spin in a circle at a high the perimeter of a cylinder and spin in a circle at a high
rate of turning. When the cylinder begins spinning very rate of turning. When the cylinder begins spinning very
rapidly, the floor is removed from under the riders' feet. rapidly, the floor is removed from under the riders' feet.
What effect does a doubling in speed have upon the What effect does a doubling in speed have upon the
centripetal force? Explain.centripetal force? Explain.
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at The Physics Classroom!at The Physics Classroom!

55. Determine the centripetal force acting upon a 40-kg child Determine the centripetal force acting upon a 40-kg child
who makes 10 revolutions around the Cliffhanger in 29.3 who makes 10 revolutions around the Cliffhanger in 29.3
seconds. The radius of the barrel is 2.90 meters.seconds. The radius of the barrel is 2.90 meters.
Answer the question and then check Answer the question and then check
at The Physics Classroom!at The Physics Classroom!