High School

You are helping with some repairs at home. You drop a hammer and it hits the floor at a speed of 12 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. 2.25 feet
B. 8.5 feet
C. 1.0 foot
D. 18.0 feet

Answer :

To solve this problem, we need to determine the height from which the hammer was dropped using the given formula:

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

where:
- [tex]\( v \)[/tex] is the velocity of the hammer when it hit the ground, which is 12 feet per second.
- [tex]\( g \)[/tex] is the acceleration due to gravity, which is 32 feet/second².

Our goal is to find [tex]\( h \)[/tex], the height from which the hammer was dropped.

1. Start by squaring both sides of the formula to eliminate the square root:

[tex]\[ v^2 = 2gh \][/tex]

2. Substitute the known values into the equation:

[tex]\[ 12^2 = 2 \times 32 \times h \][/tex]

3. Compute [tex]\( 12^2 \)[/tex], which is 144:

[tex]\[ 144 = 64h \][/tex]

4. Solve for [tex]\( h \)[/tex] by dividing both sides of the equation by 64:

[tex]\[ h = \frac{144}{64} \][/tex]

5. Simplify the fraction:

[tex]\[ h = 2.25 \][/tex]

Therefore, the hammer was dropped from a height of 2.25 feet above the ground. Thus, the correct answer is:

A. 2.25 feet