Question

A car is travelling on a straight level road with a speed of 60 km/hr is followed by another car B which is moving with a speed of 70 km/hr.When the distance between them is 2.5 km,The B car is given an accelaration of 20km/hr.After what distance and time will the car B catch up with car A?

Answer 1

Answer: The car B will catch car A after 12 minutes and at the distance of 15 km.

Explanation:

Given that,

Speed of car A = 60 km/hr

Speed of car B = 70 km/hr

Distance d = 2.5 km

Acceleration of car B $a = 20 km/hr^2$

Let us consider car A moves at time t.

The distance of car A is

$s_{A} = 60 t$

The distance of car B is

Using equation of motion

$s = ut+\dfrac{1}{2}at^2$

$s_{B}= 70t+10t^2$

The time is

$s =s_{B}-s_{A}$

$2.5 = 70t+10t^2-60t$

$2.5= 10t+10t^2$

$10t^2+10t-2.5= 0$

$t = 12 min$

The distance of car B is

$s_{B}= 70\times 0.21+10(0.21)^2$

$s_{B} = 15 km$

Hence, The car B will catch car A after 12 minutes and at the distance of 15 km.

Answer 2

Explanation:

The entire thing has clearly been explained for smooth and spontaneous understanding of all types of readers.