Question

A body is moving with a uniform acceleration covers 40m in the first 4s and 120m in the next 4s. Its initial velocity and acceleration are

Answer 1

For first 4 seconds
S = ut + 0.5at²
40 = 4u + (0.5 × a × (4)²)
40 = 4u + 8a
Divide both sides by 4
10 = u + 2a …………[1]

For first 8 seconds
S = ut + 0.5at²
40 + 120 = 8u + (0.5 × a × (8)²)
160 = 8u + 32a
Divide both sides by 8
20 = u + 4a …………[2]

Subtract [2] from [1]
10 - 20 = u + 2a - u - 4a
-10 = -2a
a = 5 m/s²

Put a = 5 in [1]
10 = u + (2 × 5)
u = 0 m/s

∴ Initial velocity is zero and acceleration is 5 m/s²

Answer 2

Explanation:

I hope it will help you!