Question

Consider uniform acceleration in one dimension.The velocity of a body at any instant is 10 m/s. After 5 sec, velocity of the particle is 20 m/s. The velocity at 3 seconds before is

• A. 8 m/sec
• B. 4 m/sec
• C. 6 m/sec
• D. 7 m/sec

Answer 1

The correct option is B 4 m/sec

Given : $u=10m/s,t=5sec,v=20m/s$
Now, $v=u+at$
$\therefore 20=10+a\times 5$
$\Rightarrow a=2m/s^2$
Let $u_1$ be the velocity of the particle before $t=3sec,v_1=u=10m/s$
Then from the relation,
$v_1=u_1+at$
$\therefore 10=u_1+2\times 3$
$or{u}_1=4m/sec$