Question

An object starts at A, and travels at a speed of 40 kmph for 5 hours. It comes to rest at B. Another object starts at A and moves towards B, an hour after the first object has started.
In order to reach the point B at the same time as the first object, with what speed must the second object travel?

• A. $40km{h}^{-1}$
• B. $25km{h}^{-1}$
• C. $50km{h}^{-1}$
• D. $22.22km{h}^{-1}$

Answer 1

The correct option is C $50km{h}^{-1}$

Given:
Speed of first object $=40km{h}^{-1}$
Time travelled by the first object = 5 h.

$\therefore$ Distance between A and B = $40\times 5=200km$

Now, the second object starts after an hour.
To reach the point B at the same time as the first object, the second object should cover the distance between A and B in the remaining time.

Distance to be covered = 200 km
Remaining time = 4 h

$\therefore$Required speed = $\frac{Distance}{Timetaken}=\frac{200}{4}=50km{h}^{-1}$