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. 8.5 feet
B. 2.25 feet
C. 1.0 foot
D. 180 feet

Answer :

To find out how far above the ground the hammer was when it was dropped, we can use the formula for velocity due to gravity:

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

where:
- [tex]\( v \)[/tex] is the velocity of the hammer when it hits the ground, which is 12 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, which we need to find.

First, we'll solve the equation for [tex]\( h \)[/tex]:

1. Square both sides to remove the square root:

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

2. Plug in the given values for [tex]\( v \)[/tex] and [tex]\( g \)[/tex]:

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

3. Calculate [tex]\( 12^2 \)[/tex]:

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

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

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

5. Simplify the fraction:

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

Thus, the hammer was dropped from a height of 2.25 feet. The correct answer is B. 2.25 feet.