JEE Main & Advanced Physics Motion in a Straight Line / सरल रेखा में गति Question Bank Topic Test - One Dimensional Motion

A bus is beginning to move with an acceleration of \[1\text{ }m{{s}^{2}}\]. A boy who is 48 m behind the bus starts running at \[10\text{ }m{{s}^{1}}\]. After what time will the boy be able to catch the bus?

A) 6 s

B) 8 s

C) 10 s

D) The boy cannot catch the bus

Correct Answer: B

Solution :

[b] The bus moves a distance, \[x=\,\frac{1}{2}\,a{{t}^{2}}\]

The man moves a distance, \[x+48=v\times t\]

\[\frac{1}{2}\,\times 1\times \,{{t}^{2}}+48=\,10t\]

\[{{t}^{2}}20t+96=0\]

\[(t12)\text{ (}t8)=0\]

\[t=12,\text{ }s,\text{ }t=8s\]

Man will cross the bus after 8 c. But again after 12 s bus will cross him due to accelerated motion.