Question

A car moving with velocity of 10 m/s and with a uniform acceleration gains a velocity of 30 m/s after travelling a distance of 4km.The time taken is.
a) 200s
b) 2000s
c) 300s
d) 3000s
(with explanation please) ​

Answer 1

Given:-

•Initial velocity of the car=10m/s

•Final velocity of the car=30m/s

•Distance covered=4km

To find:-

•Time taken

Solution:-

Here,the distance is given in km.So,we shall firstly convert the distance into m.

=>1km=1000m

=>4km=4(1000)

=>4000m

We shall use the 3rd equation of motion to find acceleration of the car.

=>v²-u²=2as

=>(30)²-(10)²=2×a×4000

=>900-100=8000a

=>800=8000a

=>a=800/8000

=>a=0.1m/s²

Hence,we have got acceleration of the car as 0.1m/s².

Now,we shall use the 1st equation of motion to find the time taken.

=>v=u+at

=>30=10+0.1×t

=>30-10=0.1t

=>20=0.1t

=>t=20/0.1

=>t=200s

Thus,the time taken is 200s and hence correct option is (a).