Question

A body is thrown vertically upward with velocity $u$ The distance travelled by it in the $7th$ and $8th$ seconds are equal. The displacement in $8th$ seconds is equal to (take $g=10m/s^2)$

• A. $5m$
• B. $10m$
• C. $2.5m$
• D. $\frac{5}{3}m$

Answer 1

Answer: (A)

$5m$

The body travels same distance in $7th$ and $8th$ second. So, it reaches its maximum height in $7s$.

After $7s$, its initial velocity is zero and it starts to move in the downward direction.

Thus, the displacement in the $8th$ second is,

$s=0+\frac{1}{2}\times 9.8\times \left(8-7\right)$

$\approx 5m$