Force Grade 7 physics, description.pptx

Force push or pull
a push or pull
it is a quantitative description on how two physical bodies interact.
a force can move an object at rest.
it can also slow down, speed up, or stop a moving object.
it can also change a body’s direction or even its shape.
Gravitational force examples
Getting up in the morning and laying down at night.
Athletes train hard to be able to jump higher.
The force that holds the gases in the sun.
The force that causes a ball you throw in the air to come down again.
A balloon that is out of helium to come back down to the ground.
Electromagnetic force examples
1. Integrated circuits in appliances.
2. The force felt on electrons in a loop of wire when near a changing magnetic field.
3. Magnets sticking artwork to a refrigerator.
4. Sticky things like tape or tar sticking to surfaces
Some of the quantities in Physics require direction while there are also some quantities that do not.

Those quantities that require both magnitude and direction for a complete description are referred to as vector quantities.
Examples of vector quantities include:
1. displacement
2. Velocity
3. Acceleration
4. Force
5. Momentum
6. and impulse

On the contrary, those quantities that do not require direction and can be described by magnitude only (numerical value) are called scalar quantities.
Sam wants to find out the shortest distance from his house to his school.

This quantity being measured is displacement.

Displacement is a quantity that requires both magnitude and direction.
Joel wants to know how fast the airplane moves and to where it is headed.

-The quantity being measured is velocity.

Velocity is a quantity that requires both magnitude and direction.
Peter wants to measure the area of his table.

-The quantity being measured is area.

Area is a scalar quantity.
Peter wants to measure the area of his table.

-The quantity being measured is area.

Area is a scalar quantity.
Sample Problem #2:
Tommy loves taking care of homing pigeons. He sent a note to his crush who lives 24.0 km away from his house. These birds fly at a rate of 48.2 km/h. How long will the note reach Tommy’s crush?

Given: distance = 24.0 km speed = 48.2 km/h
Find: time

Solution: t = d/v
t = (24.0 km)/(48.2 km/hours)
t = 0.498 hours will the note reach Tommy’s crush.

Cars speeding through the road do not always move at a constant speed. A car may travel on high gear at a top speed of 80 km/h, slow down to 20 km/h during slow traffic, or even reach 0 km/h at a stoplight.

The speedometer of the car indicates its speed.
The reading at a particular time is called instantaneous speed of the car.
Sample Problem #1:
The cheetah, the fastest land animal, can travel 625 meter in 25 seconds. What is its average speed?

Given: distance = 625 m time = 25 s
Find: average speed

Solution: ῡ = d/t
ῡ = (625 m)/(25.0 s)
ῡ = 25.0 m/s
Cars speeding through the road do not always move at a constant speed. A car may t

1. Force Grade 7 Physics

2. a push or pull i t is a quantitative description on how two physical bodies interact. a force can move an object at rest. i t can also slow down, speed up, or stop a moving object. i t can also change a body’s direction or even its shape. Force

3. EXPLAIN FORCE IN YOUR OWN WORDS.

4. if a force twists an object. a. Torsion CAN YOU GIVE 3 EXAMPLES?

5. the force that stretches an object like a rope or rubber band. b . Tension CAN YOU GIVE EXAMPLES?

6. 2 types of Forces

7. Frictional Force or friction (f) - is the force exerted by a surface as an object moves across it. 1 . Contact Forces

8. Examples of Frictional Force Rubbing both hands together to create heat. A sled sliding across snow or ice. A washing machine pushed along a floor . Skis sliding against snow. 5. An iron being pushed . 6. A block being slid.

9. b. Applied Force is a force directed to an object by a person or another object. A push, pull, or twist you exert on an object.

10. Examples of Applied Force Kneading a dough Stretching a rubber band Kicking a football Lift a dumbbell

11. c . Normal Force the support force exerted by a surface that is in contact with another object. It is always perpendicular to the surface that the object is resting on.

12. Examples of Normal Force A book is placed on a table. A person standing on a corner.

13. Gravitational Force – the force of gravity pulls objects toward the center of Earth. It also acts between each and every particle in the universe. It is always attractive and never repulsive. 2. Non- Contact Forces

14. Examples of Gravitational Force Getting up in the morning and laying down at night. Athletes train hard to be able to jump higher. The force that holds the gases in the sun. The force that causes a ball you throw in the air to come down again. A balloon that is out of helium to come back down to the ground.

15. Gravitational Force it is the gravitational force of the Earth that gives weight. The force due to gravity is always equal to the weight of the object, as indicated in the equation : W – the weight in Newton (N) m – the mass of the object in kilograms g – the acceleration due to gravity that has a value of 9.8 m/s2

16. Gravitational Force

17. b. Electromagnetic Force – It combines electric and magnetic fields from the interaction of charged particles. It is more than a billion times stronger than gravitational force because it works at an infinite distance.

18. Examples of Electromagnetic Force 1. Integrated circuits in appliances. 2. The force felt on electrons in a loop of wire when near a changing magnetic field . 3. Magnets sticking artwork to a refrigerator . 4. Sticky things like tape or tar sticking to surfaces.

19. c. Nuclear Force - is a force that acts between the protons and neutrons of atoms. It binds the protons and neutrons in a nucleus together. It exists between protons and protons, neutrons and protons or neutrons and neutrons.

20. Examples of Nuclear Force 1. Atomic bomb 2. Hydrogen Bomb 3. Nuclear fission bomb

21. 2 types of Forces GIVE EXAMPLES GIVE EXAMPLES

22. ELABORATE ( 1642 – 1727 ) Discovered the Force of Gravity He was an English physicist, mathematician, astronomer, natural philosopher, alchemist, and theologian. H e observed an apple fell to the ground and wondered what force was responsible for the event. Newton first explained that the apple fell because all objects attract other objects. Later on, he theorized that the apple fell because of an attractive force exerted by Earth on it. ISAAC NEWTON

23. Motion Grade 7 Physics

24. Motion is all around. i t can be described as either fast or slow. i n the story of the hare and tortoise, there is the idea of speed.

25. Motion What happened to the story of hare and tortoise?

26. Motion It is a change in position of an object with respect to a reference point. It can be described in terms of speed, velocity, acceleration, displacement, and time.

27. Give Examples of Motion Leaves fall, branches sway, animals run swiftly to catch their prey, people in the streets rush to get a ride, children cannot keep still in their seats, and even microbes change their routes to avoid anything in their path.

28. Variables and their Representations v speed v velocity d distance d displacement a acceleration t time

29. Scalar and Vector Grade 7 Physics

30. Some of the quantities in Physics require direction while there are also some quantities that do not. Those quantities that require both magnitude and direction for a complete description are referred to as vector quantities.

31. Examples of vector quantities include: 1. displacement 2. Velocity 3. Acceleration 4. Force 5. Momentum 6. and impulse

32. On the contrary, those quantities that do not require direction and can be described by magnitude only (numerical value) are called scalar quantities.

33. Examples of scalar quantities include: Time Mass distance ( length) Speed Temperature Area Volume and density .

34. Sam wants to find out the shortest distance from his house to his school . This quantity being measured is displacement . Displacement is a quantity that requires both magnitude and direction.

35. Joel wants to know how fast the airplane moves and to where it is headed. -The quantity being measured is velocity. Velocity is a quantity that requires both magnitude and direction.

36. Peter wants to measure the area of his table . -The quantity being measured is area. Area is a scalar quantity.

37. Trisha wants to know how long it will take for her to finish her assignment in Science . -The quantity being measured is time . Time is a scalar quantity.

38. Carol wants to find out the length of her hair . The quantity being measured is length . Length is a scalar quantity.

39. Stephanie wants to measure the body temperature of her younger sister. - The quantity being measured is temperature . Temperature is a scalar quantity.

40. Speed Grade 7 Physics

41. Speed – is the term used to describe the distance traveled per unit of time. the word “per” means “to divide by”. t he distance traveled can be in a straight line or around a corner. i t is a scalar quantity. t hey do not describe directions.

42. Speed Combinations of units for distance with respect to time: • kilometers per hour (km/h or kph ) • centimeters per second (cm/s) • meters per second (m/s) • centimeters per day (cm/day)

43. Speed To compute for speed, use the following formula:   speed =   v =     distance = speed x time     d = vt     time = t =     distance = speed x time     d = vt  

44. Speed To compute for speed, use the following formula: Nifty Triangle Trick

45. Speed To compute for speed, use the following formula:   speed =   v =     distance = speed x time     d = vt     time = t =     distance = speed x time     d = vt  

46. Sample Problem #1: Let us find the speed of the tortoise if it took five hours to travel three kilometers . Given: distance = 3 km time = 5 hours Find : speed Solution: v = d/t v = (3 km)/(5 hours) v = 0.6 km/h or 0.6 kph The tortoise traveled at a speed of 0.6 km/h.

47. Speed To compute for speed, use the following formula: Nifty Triangle Trick

48. Sample Problem #2: Tommy loves taking care of homing pigeons. He sent a note to his crush who lives 24.0 km away from his house. These birds fly at a rate of 48.2 km/h. How long will the note reach Tommy’s crush ? Given: distance = 24.0 km speed = 48.2 km/h Find : time Solution: t = d/v t = (24.0 km)/(48.2 km/hours) t = 0.498 hours will the note reach Tommy’s crush .

49. Instantaneous Speed Cars speeding through the road do not always move at a constant speed. A car may travel on high gear at a top speed of 80 km/h, slow down to 20 km/h during slow traffic, or even reach 0 km/h at a stoplight . The speedometer of the car indicates its speed. The reading at a particular time is called instantaneous speed of the car.

50. Instantaneous Speed

51. Average Speed AVERAGE SPEED ( ῡ ) - indicates the average rate of movement during the entire time of the travel (t) throughout the entire distance traveled (d). It uses the formula below: average speed = or ῡ =  

52. Sample Problem #1: The cheetah, the fastest land animal, can travel 625 meter in 25 seconds. What is its average speed ? Given: distance = 625 m time = 25 s Find: average speed Solution: ῡ = d/t ῡ = (625 m)/(25.0 s) ῡ = 25.0 m/s

53. How far can the cheetah in the previous problem go in one minute ? Given: speed = 25.0 m/s time = 1 min = 60 seconds Find: distance Solution: d = vt d = 25.0 m/s x 60 s d = 1500 m

54. Sample Problem #2: Suppose a freight train travels a distance of 120 miles in 3 hours. What is the average speed of the train? Given: distance = 120 miles time = 3 hours Find : average speed Solution: ῡ = d/t ῡ = (120 miles)/(3 hours) ῡ = 40 miles/hour

55. BRIEF REFLECTION * As a student, how are you going to be a good leader in the classroom or even in our society ? *How important is it to have those signs in the roads? Especially, the limitation of speed ? * How important is it to measure how far you will travel ?   “God is a wise and powerful! Praise him forever and ever”. (Daniel 2:20)