Question

A motor cyclist is 210 m behind a car and is
moving towards car with a velocity 40 m/sec.
Car is moving away from motorcyclist with
velocity 10 m/sec. Then find time after which
motorcyclist will over take the car :-
a.4.2sec
b.5sev
c.7sec
d.10sec​

Answer 1

Answer

c . 7 seconds

Given

Distance b/w motor cycle and car = 210 m

Relative speed = 40 - 10 = 30 m/s

To Find

Time to cross car by motor cyclist

Solution

We know that , Speed is defined as ratio of speed and time

$\implies \bf Speed=\dfrac{Distance}{TIme}\\\\\implies \rm 30=\dfrac{210}{t}\\\\\implies \rm t=\dfrac{210}{30}\\\\\implies \rm t=7\ s\ \; \green{\bigstar}$

So , Motor cyclist will take 7 s to overtake car .

More Info

• SI unit of speed is m/s
• SI unit of distance is meter
• SI unit of time is second

Answer 2

Correct Option :-

c) 7 sec.

Given :-

• A motor cyclist is 210 m behind a car
• Relative speed = 40 - 10 = 30 m/s

To Find :-

• Time after which motorcyclist will over take the car

Formula :-

We know that,

$\therefore\bf\blue{Speed=\dfrac{Distance}{Time}}$

Solution :-

Put the given values we get,

$\red{\implies \tt 30=\dfrac{210}{t}}\\\orange{\implies \tt t=\dfrac{210}{30}}\\\green{\implies \tt t=7 \: s}$

Hence, Motor cyclist will take 7s to overtake car.