Forces and Motion

Question 1

What does Newton’s first law say?

Answer 1

If the resultant force is zero then an object either remains stationary or remains moving at the same speed in the same direction.

Question 2

What does Newton’s second law say?

Answer 2

The acceleration of an object is proportional to the resultant force on the object, and inversely proportional to the mass of the object (F = m × a)

Question 3

What does Newton’s third law say?

Answer 3

When two objects interact, the forces they exert on each other are equal and opposite.

Question 4

What is the stopping distance of a vehicle?

Answer 4

Stopping distance = thinking distance + braking distance.

Question 5

What is a typical reaction time for a person?

Answer 5

0.2 to 0.9s.

Question 6

What can affect a driver’s reaction time?

Answer 6

Tiredness, drugs and alcohol.

Question 7

What can affect the braking distance of a vehicle?

Answer 7

Adverse road and weather conditions (wet/icy roads) and poor condition of the vehicle (worn tyres/brakes)

Question 8

What happens when force is applied to the brakes of a vehicle?

Answer 8

Work done by the friction force between the brakes and the wheel reduces the kinetic energy of the vehicle and the temperature of the brakes increases.

Question 9

What happens if the braking force is larger?

Answer 9

The greater the braking force the great the deceleration of the vehicle. Large decelerations may lead to brakes overheating and/or loss of control.