Inroduction to linear kinetics

Kinesiology in physical education to increase movement efficiency and performance ouput.

1. INRODUCTION TO LINEAR KINETICS. BY : Dr. DEV RAJ YADAV (ASSOCIATE PROFESSOR) MMH COLLEGE, GHAZIABAD, U.P

2. MASS: Mass (symbolized m ) is a dimensionless quantity representing the amount of matter in a particle or object. The standard unit of mass in the International System (SI) is the kilogram (kg). Mass is measured by determining the extent to which a particle or object resists a change in its direction or speed when a force is applied. Isaac Newton stated: A stationary mass remains stationary, and a mass in motion at a constant speed and in a constant direction maintains that state of motion, unless acted on by an outside force. For a given applied force, large masses are accelerated to a small extent, and small masses are accelerated to a large extent. The following formula applies: F = ma where F is the applied force in newton, m is the mass of the object or particle in kilograms, and a is the resulting acceleration in meters per second squared. The mass of an object can be calculated if the force and the acceleration are known.

3. FORCE: Push or Pull Forces can cause a change in velocity Examples: Gravity, Magnetism, Friction. Balanced Forces: Forces that act on the same object are opposite in direction are equal in size Unbalanced Forces: Forces that are NOT opposite and equal. Example: Change In Velocity, Acceleration

4. WORK: Work is defined (in calculus terms) as the integral of the force over a distance of displacement. In the case of a constant force, work is the scalar product of the force acting on an object and the displacement caused by that force. Though both force and displacement are vector quantities, work has no direction due to the nature of a scalar product. The SI units for work are the joule (J) or newton-meter (N * m) W = F * s where W is work, F is force, and s is the displacement. The joule is also the SI unit of energy.

5. ENERGY: Energy can be defined as the capacity for doing work . The simplest case of mechanical work is when an object is standing still and we force it to move. The energy of a moving object is called kinetic energy. For an object of mass m, moving with velocity of magnitude v, this energy can be calculated from the formula E= 1/2 mv^2. POWER: Power is the work done in a unit of time. In other words, power is a measure of how quickly work can be done. The unit of power is the Watt = 1 Joule/ 1 second .

6. IMPULSE: When a force acts on an object for a short amount of time, impulse is the measure of how much the force changes the momentum of an object. Formula: impulse = force * time. This formula relates impulse to the change in the momentum of the object. Impulse has two different units, either kilogram times meters per second (kg m/s) or Newton times seconds (Ns).

7. FRICTION: Force that opposes motion between 2 surfaces Depends on the: types of surfaces force between the surfaces. Types of Friction: Static Friction: (Couch Potato) Force between objects at rest Sliding Friction: (Ice skating) Solid surfaces slide over each other Rolling Friction: (Rollerblading) An object rolls over a surface. Fluid friction: (S ubmarine) An object moves through a fluid

8. Newton’s 1 st Law: An object at rest remains at rest and an object in motion will continue moving at a constant velocity unless acted on by unbalanced forces. INERTIA tendency of an object to resist any change in its motion increases as mass increases

9. Newton‘s 2 nd Law: If more force is applied, an object will be accelerated more. More force means more acceleration More mass means less acceleration Force = mass X acceleration F = ma

10. Newton’s 3 rd Law: For every action, there is an equal and opposite reaction. Forces occur only in pairs Act on different objects Equal and opposite The hammer exerts a force on the nail to the right. The nail exerts an equal but opposite force on the hammer to the left.

11. EQUILIBRIUM: When all the forces that act upon an object are balanced, then the object is said to be in a state of equilibrium . The forces are considered to be balanced if the rightward forces are balanced by the leftward forces and the upward forces are balanced by the downward forces. An object at equilibrium is either ... at rest and staying at rest, or in motion and continuing in motion with the same speed and direction

12. LEVER: It is a rigid bar or rod pivoted at a fixed hinge, or fulcrum. A lever is a rigid body capable of rotating on a point on itself. A lever amplifies an input force to provide a greater output force, which is said to provide leverage. There are three type of lever: FIRST CLASS LEVER: A first-class lever is a stick where the fulcrum is between the weight and the energy moving the weight (your hands, for example). Some common first-class levers are see-saws, crowbars, pliers, scissors (which use two first-class levers together), and a hammer pulling a nail .

13. SECOND HAND LEVER: A second-class lever is a stick where the fulcrum is at one end of the stick, you push on the other end, and the weight is in the middle of the stick. Some common second-class levers are doors, staplers, wheelbarrows, and can openers . THIRD HAND LEVER: A third-class lever is a stick where the fulcrum is at one end of the stick, you push on the middle, and the weight is at the other end of the stick. With a third-class lever, you have to put in more energy than you would just lifting the weight, but you get the weight to move a longer distance in return. Some common examples are a broom, a hoe, a fishing rod, a baseball bat, and our own human arms.

14. THANK YOU