O-LevelPhysicsKinematics5054/22 · May/June 2022 · Q715 Marks
Fig. 7.1 shows the speed-time graph for a car travelling on a straight horizontal road. [Figure 7.1] (b) The thinking distance is the distance travelled by a car between the time that a hazard is seen and the time that the brakes are applied. The braking distance is the distance travelled while the car slows down to rest. Table 7.1 shows the thinking and braking distances for an alert driver when the car travels at different speeds.
- (a)(i)Describe the motion of the car.[3]
- (a)(ii)Using Fig. 7.1, calculate the distance travelled by the car during the 24 s of its motion. Show your working.[3]
- (a)(iii)Calculate the average speed of the car during its motion.[2]
- (a)(iv)A second car travels at a steady speed. It travels the same distance as the first car in the 24 s of the journey. On Fig. 7.1, draw the speed-time graph for the second car.[2]
- (b)(i)Complete Table 7.1.[1]
- (b)(ii)The time it takes for the driver to react to the hazard is constant at different speeds. Explain how the table shows this.[2]
- (b)(iii)State what happens to the thinking distance and the braking distance when the driver is tired. thinking distance ..., braking distance ...[2]
This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.
Mark scheme
Marking points from the official mark scheme (May/June 2022). The mark or mark type is shown in brackets.
- [1] acceleration constant / for 10 s or acceleration 1.6 m/s² or speeds up for 10 s / until it reaches 16 m/s
- [1] constant / uniform speed for 10 s / from 10 to 20 s / of 16 m/s or zero acceleration for 10 s / from 10 to 20 s
- [1] decelerates constantly / for 4 s / from 20 s to 24 s / until 24 s or deceleration 4 m / s² or acceleration -4 m/s²
- [1] area under curve or formula for area of a triangle / trapezium seen or working shown used
- [1] (accelerating) 80 (m) or (at constant speed) 160 (m) or (decelerating) 32 (m) seen
- [1] (total distance) 270 or 272 m
- [1] (average speed) = total distance / (total) time algebraic or numerical
- [1] 11 m/s
- [1] horizontal line drawn from 0 to 24 s at any level OR horizontal line at the value calculated in 7(a)(iii) for at least 16 s
- [1] horizontal line from 0 to 24 s at the value calculated in 7(a)(iii)
- [1] 27
- [1] (statement that thinking) distance is proportional to speed OR thinking distance increases uniformly with speed OR time = (thinking) distance / speed and stated to be equal / not affected OR ratio of (thinking) distance to speed is constant OR (thinking) distance and speed both increase by same ratio OR same change in (thinking) distance for equal changes in speed
- [1] at least two values thinking distance ÷ speed (or inverse) calculated OR all values of thinking distance/speed stated to be 0.45 (or inverse 2.2) OR proportionality shown by at least two values OR double the speed doubles the (thinking) distance OR each 20 (km/h)/same increase in speed covers an extra 9 (m) distance
- [1] thinking distances increases
- [1] braking distances no change
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