Motion and Force

Question 1

Why does a apple reach the ground first over a leaf,

Answer 1

air resistance depends on shape
[or other correct statement about air resistance
air resistance less significant
air resistance less, therefore greater velocity

Question 2

the leaf accelerates at first then reaches a terminal velocity, explain how

Answer 2

gravity greater than air resistance
[or (initially only) weight/gravity acting
hence resultant force downwards or therefore acceleration (2nd law)
air resistance or upward force increases with speed
until air resistance equals weight or resultant force is zero

Question 3

Newtons second law

Answer 3

Acceleration is produced when a force acts on a mass. The greater the mass (of the object being accelerated) the greater the amount of force needed (to accelerate the object).

Question 4

What would the energy changes be for a girl jumping in the air from a trampoline

Answer 4

-(elastic potential) energy is transformed to kinetic
energy
- (the gymnast) must bend knees (do work) (to increase height)
- Work is done against the resistive forces