High School

You are helping with some repairs at home. You drop a hammer, and it hits the floor at a speed of 8 feet per second. If the acceleration due to gravity [tex]$(g)$[/tex] is 32 feet/second [tex]${}^2$[/tex], how far above the ground [tex]$(h)$[/tex] was the hammer when you dropped it?

Use the formula:

[tex]v = \sqrt{2gh}[/tex]

A. 16.0 feet
B. 1.0 foot
C. 8.0 feet
D. 2.0 feet

Answer :

To find the height from which the hammer was dropped, we can use the formula for the velocity of an object falling freely under gravity:

[tex]\[ v = \sqrt{2gh} \][/tex]

Where:
- [tex]\( v \)[/tex] is the final velocity of the hammer when it hits the ground, which is 8 feet per second.
- [tex]\( g \)[/tex] is the acceleration due to gravity, which is 32 feet per second squared.
- [tex]\( h \)[/tex] is the height from which the hammer was dropped, and this is what we want to find.

Let's solve for [tex]\( h \)[/tex]:

1. Start with the formula:
[tex]\[ v = \sqrt{2gh} \][/tex]

2. Square both sides of the equation to eliminate the square root:
[tex]\[ v^2 = 2gh \][/tex]

3. Rearrange the equation to solve for [tex]\( h \)[/tex]:
[tex]\[ h = \frac{v^2}{2g} \][/tex]

4. Substitute the known values into the equation:
[tex]\[ h = \frac{8^2}{2 \times 32} \][/tex]

5. Calculate [tex]\( 8^2 \)[/tex], which is 64. Then multiply 2 by 32, which is 64.

6. Divide 64 by 64 to find [tex]\( h \)[/tex]:
[tex]\[ h = \frac{64}{64} = 1.0 \][/tex]

Therefore, the hammer was dropped from a height of 1.0 foot. So, the correct answer is:

B. 1.0 foot