Question

A 4 KG object falls from 10 m. What is it potential energy at the top?

196 J
784 J
392 J
40 J

Answer 1

The potential energy (PE) of an object at a height can be calculated using the formula:

\[
PE = m \cdot g \cdot h
\]

where:
- \( m \) is the mass of the object (in kg),
- \( g \) is the acceleration due to gravity (approximately \( 9.81 \, \text{m/s}^2 \)),
- \( h \) is the height (in meters).

Given:
- \( m = 4 \, \text{kg} \)
- \( g = 9.81 \, \text{m/s}^2 \)
- \( h = 10 \, \text{m} \)

Now, substitute these values into the formula:

\[
PE = 4 \, \text{kg} \cdot 9.81 \, \text{m/s}^2 \cdot 10 \, \text{m}
\]

\[
PE = 4 \cdot 9.81 \cdot 10
\]

\[
PE = 4 \cdot 98.1 = 392.4 \, \text{J}
\]

Rounding this to the nearest whole number gives us approximately \( 392 \, \text{J} \).

Thus, the potential energy at the top is **392 J**.