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. 18.0 feet
B. 8.5 feet
C. 1.0 foot
D. 2.25 feet

Answer :

To find the height from which the hammer was dropped, we can use the formula for the relationship between speed, gravity, and height:

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

where:
- [tex]\( v \)[/tex] is the final speed of the hammer (12 feet per second),
- [tex]\( g \)[/tex] is the acceleration due to gravity (32 feet/second[tex]\(^2\)[/tex]),
- [tex]\( h \)[/tex] is the height from which the hammer was dropped.

We need to solve for [tex]\( h \)[/tex]. Here's how you can do it step-by-step:

1. Start with the formula:

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

2. Square both sides to get rid of the square root:

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

3. Solve for [tex]\( h \)[/tex] by dividing both sides by [tex]\( 2g \)[/tex]:

[tex]\[ h = \frac{v^2}{2g} \][/tex]

4. Plug in the known values ([tex]\( v = 12 \)[/tex] feet/second and [tex]\( g = 32 \)[/tex] feet/second[tex]\(^2\)[/tex]):

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

5. Calculate:

[tex]\[ h = \frac{144}{64} \][/tex]
[tex]\[ h = 2.25 \][/tex]

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

D. 2.25 feet