Question

a roller coaster with a potential energy of 235,200 j sits at the top of a 30 m high hill. what is the mass of the roller coaster? (formula: pe = mgh) 7,840 kg 78,400 kg 800 kg 8,000 kg

Explanation:

Step1: Rearrange the potential - energy formula

Given $PE = mgh$, we can solve for $m$ by the formula $m=\frac{PE}{gh}$. Here, $g = 9.8\ m/s^{2}$ (acceleration due to gravity), $h = 30\ m$ and $PE=235200\ J$.

Step2: Substitute the values

Substitute $PE = 235200\ J$, $g = 9.8\ m/s^{2}$ and $h = 30\ m$ into the formula $m=\frac{PE}{gh}$. So $m=\frac{235200}{9.8\times30}$.
First, calculate $9.8\times30 = 294$. Then $m=\frac{235200}{294}=800\ kg$.

Answer:

$800\ kg$