High School

You are helping with some repairs at home. You drop a hammer and it hits the floor at a speed of 4 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. 0.5 feet
D. 0.25 feet

Answer :

To find out how high above the ground the hammer was when it was dropped, you can use the formula for the velocity of an object in free fall:

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

Here, [tex]\( v \)[/tex] represents the velocity of the object when it hits the ground, [tex]\( g \)[/tex] is the acceleration due to gravity, and [tex]\( h \)[/tex] is the height from which the object was dropped.

Given values:
- [tex]\( v = 4 \)[/tex] feet per second (the speed at which the hammer hits the floor),
- [tex]\( g = 32 \)[/tex] feet per second squared (the acceleration due to gravity).

We need to rearrange the formula to solve for [tex]\( h \)[/tex]:

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

2. Square both sides to eliminate 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. Substitute the known values into the equation:
[tex]\[ h = \frac{4^2}{2 \times 32} \][/tex]

5. Calculate the result:
[tex]\[ h = \frac{16}{64} = 0.25 \][/tex]

Therefore, the hammer was dropped from a height of 0.25 feet above the ground. So the correct answer is:

D. 0.25 feet