Question

A penny is dropped from the top of a building that is 111 m to the ground. What is it’s final speed in m/s

Answer 1

Let the mass of the penny be m.

The height of the building is h = 111 m

Let the velocity be denoted by v.

According to the conservation of energy,

`\begin{gathered} K\text{inetic Energy = Potential energy} \\ (1)/(2)mv^2=mgh \end{gathered}`

Here, g = 9.81 m/s^2 is the acceleration due to gravity.

The speed will be

`v=\sqrt[]{2gh}`

Substituting the values, the speed will be

`\begin{gathered} v=\sqrt[]{2*9.81*111} \\ =46.67\text{ m/s} \end{gathered}`

Thus, the speed is 46.67 m.