conservation of energy and friction

Question 1

1) what happens to the energy of an object when it falls (ignoring friction)
2) what happens to speed of object?

Answer 1

1) - loss in gravitational potential energy
- gain in kinetic energy
2) - max possible speed of the object
- speed would be less
- some of initial gravitational potential energy transferred to surroundings as thermal energy due to friction and/or air resistance

Question 2

what happens to the energy of an object when it is thrown in the air

Answer 2

• loss in kinetic energy
• gain in gravitational potential energy

Question 3

what happens to energy of an object when its moves on a surface

Answer 3

-kinetic energy store constantly transferred to the surfaces thermal energy store
- because of friction or air/water resistance

Question 4

why must work constantly be done against friction

Answer 4

• to maintain constant speed
• and thus constant kinetic energy

Question 5

what happens to the kinetic energy of an object if there is no friction e.g in space

Answer 5

• object continue moving with the same kinetic energy
• no additional work being done