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

Options

A. `1:1`
B. `11:1`
C. `1:2`
D. `1:11`

Answer

B

Explanation

Time of ascent `(t) = u/g rArr u = 6 xx 10 = 60m//s`
distance travelled in nth second
`S_n = u - a/2 (2n-1)`
`S_1 = 60-g/2 = 55m`
`S_7 = g/2(2n - 1)`
Distance in 7th second will be equal to the distance in 1st second of vertical downward motion
`S_7 = S_1 = g/2 (2 -1 ) = 5m`
`S_1/S_7 = 55/5 = 11:1`