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

Answer :

We start with the formula that relates the final speed [tex]$v$[/tex], the acceleration due to gravity [tex]$g$[/tex], and the height [tex]$h$[/tex] from which the hammer is dropped:
[tex]$$
v = \sqrt{2gh}.
$$[/tex]

Our goal is to find the height [tex]$h$[/tex]. We begin by squaring both sides of the equation to eliminate the square root:
[tex]$$
v^2 = 2gh.
$$[/tex]

Next, we solve for [tex]$h$[/tex] by dividing both sides by [tex]$2g$[/tex]:
[tex]$$
h = \frac{v^2}{2g}.
$$[/tex]

Now, we substitute the given values [tex]$v = 12$[/tex] feet per second and [tex]$g = 32$[/tex] feet/second[tex]$^2$[/tex] into the equation:
[tex]$$
h = \frac{12^2}{2 \times 32}.
$$[/tex]

Calculating the numerator:
[tex]$$
12^2 = 144.
$$[/tex]

Calculating the denominator:
[tex]$$
2 \times 32 = 64.
$$[/tex]

Thus, the height is:
[tex]$$
h = \frac{144}{64} = 2.25 \text{ feet}.
$$[/tex]

Therefore, the hammer was dropped from a height of [tex]$2.25$[/tex] feet, which corresponds to option C.