Question

10. A body is thrown vertically upward with velocity
The distance travelled by it in the 7th and 8th
seconds are equal. The displacement in 8th
seconds is equal to (take g = 10 m/s2)
(1) 5 m
(2) 10 m
(3) 2.5 m
(4)5/3​

Answer 1

answer : option (1) 5m.

explanation : A body is thrown vertically upward with velocity u.

the distance travelled by it in the 7th and 8th seconds are equal.

it is possible only when particle reaches maximum height at 7th and after that body falls freely under gravity.

we have to find distance travelled in 8th sec by body.

in time interval, 7sec to 8sec

velocity at 7s , u = 0

time duration , t = 8sec - 7sec = 1sec

now distance travelled in 8th second , s = ut + 1/2 at²

= 0 + 1/2 g × 1²

= 5m

hence, answer should be 5m