Question

A penny is dropped from a height of 50.0m. If the acceleration due to gravity is 9.8 m/s2 and air resistance is disregarded, what is the speed of the penny as it hits the ground?

Answer 1

Answer on Question #57583-Physics – Mechanics | Relativity

A penny is dropped from a height of 50.0m. If the acceleration due to gravity is 9.8 m/s² and air resistance is disregarded, what is the speed of the penny as it hits the ground?

Solution

If air resistance is disregarded we can use the equations for the body moving with constant acceleration.

$$2aS = v_f^2 - v_i^2.$$ $$v_i = 0; S = h; a = g; v_f = v.$$

The speed of the penny as it hits the ground is

$$v = \sqrt{2gh} = \sqrt{2 \cdot 9.8 \frac{\mathrm{m}}{\mathrm{s}^2} \cdot 50.0\ \mathrm{m}} = 31.3 \frac{\mathrm{m}}{\mathrm{s}}.$$

Answer: $31.3 \frac{\mathrm{m}}{\mathrm{s}}$.

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