Question

If a coin is thrown with a starting velocity of 0 m/s down a dry well and hits bottom in 1.2 s, what's the depth of the well? With what velocity does the coin in the previous problem hit the bottom?

Answer 1

Depth = 7.06 m

Velocity = 11.77 ms-1

Explanation:

We use the equation of motion:-

s = ut + 1/2 g
`t^(2)` where s = distance fallen , t = time , u = initial velocity and g = 9.81 ms^-2 , the acceleration due to gravity.

So s = 0(t) + 1/2 * 9.81 (1.2)^2

= 7.06 m to nearest tenth.

We use another equation of motion to find the final velocity:-

v^2 = u^2 + 2gs where v = final velocity

v^2 = 0 + 2*9.81 * 7.06

= 138.52

v = √138.52 = 11.77 m s-1