P2.2.5 - Everyday forces and their effects

Question 1

What is free fall?

Answer 1

The fall of a body through a medium, without a drag producing device

Question 2

What is terminal velocity?

Answer 2

The velocity at which a body falls through a medium, when the drag acting on the body is equal to its weight

Question 3

Explain why terminal velocity is a constant speed?

Answer 3

• At terminal velocity, the weight of a body is balanced by the drag force acting on it
• Thus, the resultant force is zero and the body does not accelerate

Question 4

What is the journey of a skydiver who jumps out of a plane?

Answer 4

• When they jump out the only force acting on them is weight due to gravity so they experience a resultant force acting downwards, so they accelerate towards the ground
• As they fall, they experience air resistance which is friction with air molecules
• As weight is still greater than air resistance they continue to accelerate downwards
• As the skydiver’s velocity increases the air resistance also increases
• At a certain point the weight will balance air resistance
• After this the skydiver opens their parachute which increases the surface are causing air resistance to massively increase
• This causes the skydiver to decelerate
• Because the velocity has decreased, the air resistance has also decreased
• At one point both weight and air resistance will balance and the diver will fall at low terminal velocity