Question

A body moving with uniform acceleration describes 4 m in the third second and 12 m in the fifth second. The distance described in the next three seconds is ______.

Options

• 100 m

• 80 m

• 60 m

• 20 m

Answer 1

A body moving with uniform acceleration describes 4 m in the third second and 12 m in the fifth second. The distance described in the next three seconds is 60 m.

Explanation:

a = constant

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

`4 = S_3 = u + a/2(5)` ...........(1)

`12 = S_5 = u + a/2(9)` ................(2)

On solving (1) and (2),

We get u = -6 m/s

and a = 4 m/s² 

Distance covered in 8 s,

`S_1 = -6 xx 8 + 1/2 xx 4 xx 25`

= 80 m

Distance covered in 5 s,

`S_2 = -6 xx 5 + 1/2 xx 4 xx 25`

= 20 m

Distance covered in next three seconds,

= 80 m - 20 m = 60 m