Question

A body is through vertically upwards with an initial velocity 'u' reaches a maximum height in 6s. The ratio of the distance travelled by the body in the first second to the seventh second is then

• A. 1:1
• B. 11:1
• C. 1:2
• D. 1:11

Answer 1

The correct option is B 11:1

It is given that, the body reaches the maximum height in 6s. Let u be the initial velocity. At maximum height the velocity is zero. Using the equation of motion as

$v=u+at$

$0=u-\left(10\right)\left(6\right)$

$u=60m/s$

Distance travelled in n^th second is given by:

$S_n=u+\left(\frac{a}{2}\right)(2n-1)$

Displacement in 1^st second is $S_1=60-\left(\frac{10}{2}\right)(2-1)=55m$

Displacement in 7^th second is $S_2=60-\left(\frac{10}{2}\right)(14-1)=-5m$

So, $\frac{S_1}{S_2}=\frac{55}{5}=\frac{11}{1}$

The ratio is $11:1$.