9702/Oct Nov/12/2017/Q7

The velocity-time graph for a train starting at one station and stopping at the next is shown.

Another train has double the acceleration but the same maximum speed and the same

deceleration.

Which velocity-time graph, on the same scale, shows the motion of this train between the same

stations?

Solution:

Answer: B

From option A to D, we know that all of the acceleration become double from beginning, after that same maximum speed and at the end same deceleration.

However, the question had mentions the same station for the train (which mean same displacement).

The displacement of the train = velocity x time
= the area of trapezium of the graph.
= 1/2 (11+5)(8)
= 64m

For option A, the displacement = 1/2 (9+5)(8) = 56m

For option B, the displacement = 1/2 (10+6)(8) = 64m

For option C, the displacement = 1/2 (8+4)(8) = 48m

For option D, the displacement = 1/2 (11+7)(8) = 72m

Reference: PYQ - Oct/Nov 2017 Paper 12 Q7