Question

A barrel accelerates uniformly, from 10.0 m/s, 80.0 m down a hill reaching a speed of 15m/s.
How long it will take to do this?​

Answer 1

Given:-

• Initial velocity ,u = 10m/s

• Final velocity ,v = 15m/s

• Distance travelled ,s = 80m

To Find:-

• Time taken by the barrel ,t

Solution:-

Firstly we calculate the acceleration of the barrel.

So by using 3rd equation of motion

• v² = u² +2as

Substitute the value we get

→ 15² = 10² + 2×a ×80

→ 225 = 100 + 160×a

→ 225-100 = 160×a

→ a = 125/160

→ a = 0.78m/s²

Now using first equation of motion

• v = u+at

Substitute the value we get

→ 15 = 10 +0.78×t

→ 15-10 = 0.78×t

→ 5 = 0.78×t

→ t = 5/0.78

→ t = 6.41 s

∴ The time taken by the barrel is 6.41 Second.