High School

A roller coaster with a potential energy of [tex]$235,200 \, \text{J}$[/tex] sits at the top of a 30 m high hill. What is the mass of the roller coaster?

(Formula: [tex]PE = mgh[/tex])

A. 800 kg
B. 7,840 kg
C. 8,000 kg
D. 78,400 kg

Answer :

To solve for the mass of the roller coaster, we start with the formula for gravitational potential energy:

$$
PE = mgh
$$

where
\( PE \) is the potential energy,
\( m \) is the mass,
\( g \) is the acceleration due to gravity, and
\( h \) is the height.

Given:
\( PE = 235200 \, \text{J} \)
\( h = 30 \, \text{m} \)
\( g = 9.8 \, \text{m/s}^2 \)

We rearrange the formula to solve for mass \( m \):

$$
m = \frac{PE}{gh}
$$

Plug in the values:

$$
m = \frac{235200}{9.8 \times 30}
$$

First, calculate the denominator:

$$
9.8 \times 30 = 294
$$

Now, divide to find \( m \):

$$
m = \frac{235200}{294} = 800 \, \text{kg}
$$

Thus, the mass of the roller coaster is \( \boxed{800 \, \text{kg}} \).