A van is travelling at 52 km/h, when brakes are applied it comes to rest in 5 s. Another van is travelling at 3 km/h and when brakes are applied it comes to rest in 10 s. Plot the speed versus time graph and calculate the braking distance for both the vans? [3 MARKS]

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Solution

Diagram : 1 Mark
Distance1 : 1 Mark
Distance2 : 1 Mark

Step 1: Plot the speed-time graph using the information given.

Step 2: Calculate the area under the graph to calculate the braking distance.
Distance covered by the van moving at 52 km/hr
or $52 \times \frac{5}{18} = 14.4 m / s$
$= A r e a o f t r i a n g l e = \frac{1}{2} \times P Q \times Q R$
$= \frac{1}{2} \times 14.4 \times 5 = 36 m$

(ii) Distance covered by the van moving at 3 km/hr
or, $3 \times \frac{5}{18} = 0.83 m / s$
$A r e a o f t r i a n g l e = \frac{1}{2} \times L Q \times Q N$
$= \frac{1}{2} \times 0.83 \times 10$
$= 4.15 m$

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