High School

You are helping with some repairs at home. You drop a hammer, and it hits the floor at a speed of 8 feet per second. If the acceleration due to gravity ([tex]g[/tex]) is 32 feet per second squared, 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. 8.0 feet
C. 2.0 feet
D. 16.0 feet

Answer :

We start with the formula for the speed of an object in free fall:

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

To find the height [tex]$h$[/tex], we first square both sides of the equation:

[tex]$$
v^2 = 2gh.
$$[/tex]

Now, solve for [tex]$h$[/tex] by dividing both sides by [tex]$2g$[/tex]:

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

Given that the speed when the hammer hits the floor is [tex]$v = 8$[/tex] feet per second and the acceleration due to gravity is [tex]$g = 32$[/tex] feet per second[tex]$^2$[/tex], we substitute these values into the equation:

[tex]$$
h = \frac{8^2}{2 \cdot 32}.
$$[/tex]

Calculate the numerator:

[tex]$$
8^2 = 64,
$$[/tex]

and the denominator:

[tex]$$
2 \cdot 32 = 64.
$$[/tex]

Thus, the height is

[tex]$$
h = \frac{64}{64} = 1.0 \text{ foot}.
$$[/tex]

So, the hammer was dropped from [tex]$\boxed{1.0 \text{ foot}}$[/tex] above the ground.