Question

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]

Answer 1

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 $52\times \frac{5}{18}=14.4m/s$
$=Areaoftriangle=\frac{1}{2}\times PQ\times QR$
$=\frac{1}{2}\times 14.4\times 5=36m$

(ii) Distance covered by the van moving at 3 km/hr
or, $3\times \frac{5}{18}=0.83m/s$
$Areaoftriangle=\frac{1}{2}\times LQ\times QN$
$=\frac{1}{2}\times 0.83\times 10$
$=4.15m$