Question

Question 17
pe=mgh

An Olympic bodybuilder lifts a 1325 kg weight a vertical distance of 2.5 m off the ground. What potential energy do the weights have now?

a
31,462.5 J
b
34,462.5 J
c
33,462.5 J
d
32,462.5 J

Answer 1

To calculate the potential energy (PE) gained by lifting the weight, you can use the formula:

\[ PE = mgh \]

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

Given:
- \( m = 1325 \, \text{kg} \)
- \( h = 2.5 \, \text{m} \)
- \( g = 9.81 \, \text{m/s}^2 \)

Substituting these values into the formula:

\[ PE = 1325 \, \text{kg} \times 9.81 \, \text{m/s}^2 \times 2.5 \, \text{m} \]

Calculating step-by-step:

1. Calculate \( 1325 \times 9.81 = 12993.25 \, \text{kg m/s}^2 \) (which is the force in Newtons).
2. Now multiply by the height:

\[ PE = 12993.25 \, \text{N} \times 2.5 \, \text{m} = 32483.125 \, \text{J} \]

Rounded to the appropriate number of significant figures, the potential energy is approximately:

\[ PE \approx 32483.125 \, \text{J} \]

Looking at the options provided, the closest answer is:

**d. 32,462.5 J**.