A 2.0-kg projectile moves from its initial position to a point that is displaced 20 m horizontally and 15 m above its initial position. How much work is done by the gravitational force on the projectile?
A) +0.29 kJ
B) −0.29 kJ
C) +30 J
D) −30 J
E) −50 J

Question

Quizplus · Accepted Answer

The work done by the gravitational force on the projectile can be calculated using the formula $W = mgh$, where $m$ is the mass, $g$ is the acceleration due to gravity (approximately $9.8 \, \text{m/s}^2$), and $h$ is the height change. Substituting the given values, $W = 2.0 \, \text{kg} \times 9.8 \, \text{m/s}^2 \times 15 \, \text{m} = 294 \, \text{J}$. Since the work is done against the gravitational force (the force is in the opposite direction of the displacement), the work done by gravity is negative, making the correct answer $-294 \, \text{J}$, which is closest to option B, $-0.29 \, \text{kJ}$.

A 20-Kg Projectile Moves from Its Initial Position to a Point