Question

An object falls from the top of a building that is 25 m high. Air resistance is negligible What is the speed of the object when it hits the ground?

• A. 10 m/s
• B. 22 m/s
• C. 25 m/s
• D. 625 m/s

Answer 1

The correct option is B

22 m/s

Step 1:Given:

Initial velocity, $u=0m/s$

Height of the building, $h=25m$

Acceleration due to gravity, $g=10m/s^2$

Step 2: Finding the final velocity when the object hits the ground:

From the equations of the motion, we know that

$$\begin{gathered} v²+u²=2gh \\ v²=2gh[asinitialvelocityis0] \end{gathered}$$

By substituting the given values, we get

$$\begin{gathered} v=\sqrt{2gh}=\sqrt{2\times 10\times 25} \\ =\sqrt{500} \\ =22.36m/s\approx 22m/s \end{gathered}$$

Hence, the final velocity of the object is 22m/s.