# The physics of Rugby

- Created by: Nadia
- Created on: 20-12-12 18:39

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- The Physics of Rugby
- Work is done when energy is transfered from one form to another
- the unit of work is a joule (J)
- the equation for work done is: force used (N) x distance moved in the direction of the force (m)

- There is always a proportion of energy lost as heat/ sound when energy is transferred from one form to another
- human muscles are about 25% efficient i.e. 75% energy is wasted as heat rather than kinetic energy

- the equation to find the kinetic energy of a moving object is KE = 0.5mv^2
- for objects moving through the air in an upwards direction,their kinetic energy will gradually change to gravitational potential energy as the object does work against gravity
- the object will start to slow down as it has less kinetic energy
- PE (gravitational potential energy) = mass(kg)x gravitational strength(g) x change in height(m)
- when all the kinetic energy of the object has converted to gravitational potential energy+ the vertical velocity is zero- the object starts to fall
- the potential energy starts to convert back to kinetic energy

- when all the kinetic energy of the object has converted to gravitational potential energy+ the vertical velocity is zero- the object starts to fall

- PE (gravitational potential energy) = mass(kg)x gravitational strength(g) x change in height(m)

- the object will start to slow down as it has less kinetic energy
- during the object's movement, the total energy remains constant (kinetic energy + potential energy)

- for objects moving through the air in an upwards direction,their kinetic energy will gradually change to gravitational potential energy as the object does work against gravity
- Newton's third law says:"In an interaction between two objects (A+B) the force exerted on A by B is equal+ oppositely directed to the force exerted on B by A
- Together the action force and the reaction force make an interaction pair
- 'Contact forces' are where the objects must have contact to exert the force/ may be 'action at a distance' forces like gravity/ electromagnetic forces

- Together the action force and the reaction force make an interaction pair

- Work is done when energy is transfered from one form to another

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