The Highway Code gives this information about the stopping distance of a car - Edexcel - GCSE Physics - Question 1 - 2012 - Paper 1

The driver’s thinking distance is most likely to increase when:

• A (the driver is tired) – Correct, because tiredness can impair reaction time.
• B (there is ice on the road) – Incorrect, as this affects braking distance, not thinking distance.
• C (the car is heavier) – Incorrect, as this is not a direct factor affecting thinking distance.
• D (the car moves at a slower speed) – Incorrect, as slower speeds generally reduce thinking distance.

Thus, the correct option is A.

Momentum is defined as the product of mass and velocity. It can be calculated using the formula:

$$ext{Momentum} = ext{Mass} imes ext{Velocity}$$

Given:

• Mass = 800 kg
• Velocity = 3.0 m/s

So,

$$ext{Momentum} = 800 ext{ kg} imes 3.0 ext{ m/s} = 2400 ext{ kg m/s}$$

Work done by a force is calculated using the formula:

$$ext{Work} = ext{Force} imes ext{Distance}$$

Given:

• Force = 600 N
• Distance = 15 m

Thus,

$$ext{Work} = 600 ext{ N} imes 15 ext{ m} = 9000 ext{ J}$$

The work done by the brakes during braking is equal to:

• A (the energy transferred) – Correct, as work done is a measure of energy transfer.
• B (the stopping distance) – Incorrect; it relates but is not equal.
• C (the acceleration) – Incorrect; acceleration is not directly related.
• D (the thinking distance plus braking distance) – Incorrect; this sums distances, not work done.

Thus, the correct option is A.