Question

A body is thrown vertically upwards with initial velocity u reaches maximum height in 6seconds.the ratio of the distance travelled by the body in the first second and seventh second is?

Answer 1

Dear student,
Let ‘u’ be the initial velocity. At maximum height the velocity is zero and it reaches maximum height in 6 s.

Using,

v = u + at

=> 0 = u –(9.8)(6)

=> u = 58.8 m/s

Distance travelled in nth second is given by,

S_n = u + (a/2)(2n - 1)

Displacement in 1^st second is, S₁ = 58.8 – (9.8/2)(2 - 1) = 53.9 m

Displacement in the 7^th second is, S₇ = 58.8 – (9.8/2)(14 - 1) = -4.9 m

The negative sign indicates the body is moving downward in the 7^th second.

So, the required ratio of distance travelled is, |S₁| : |S₇| = 53.9 : 4.9 = 11 : 1
Regards