AP Physics 1 practice questions on Work-Potential Energy

📚 Topic Summary

Work and potential energy are fundamental concepts in physics. Work is the energy transferred to or from an object by a force causing displacement. It's calculated as $W = F \cdot d \cdot cos(\theta)$, where $F$ is the force, $d$ is the displacement, and $\theta$ is the angle between them. Potential energy, on the other hand, is stored energy that an object has due to its position or configuration. Gravitational potential energy is given by $U_g = mgh$, where $m$ is mass, $g$ is the acceleration due to gravity, and $h$ is height. Elastic potential energy (for springs) is $U_s = \frac{1}{2}kx^2$, where $k$ is the spring constant and $x$ is the displacement from equilibrium.

The work-energy theorem states that the net work done on an object equals its change in kinetic energy: $W_{net} = \Delta KE$. Conservative forces, like gravity and spring forces, are path-independent, meaning the work done by them only depends on the initial and final positions. Non-conservative forces, like friction, are path-dependent, and the work done by them results in energy dissipation (usually as heat).

🧮 Part A: Vocabulary

Match the terms with their definitions:

✍️ Part B: Fill in the Blanks

Complete the following paragraph using the words: kinetic, potential, work, conservative, non-conservative.

The total mechanical energy of a system is the sum of its ________ and ________ energies. The ________ done by ________ forces depends only on the initial and final positions, while ________ forces dissipate energy as heat or sound.

🤔 Part C: Critical Thinking

A roller coaster car starts at rest at the top of a hill. Describe how energy transforms between potential and kinetic energy as the car moves down the hill and then up another smaller hill. What happens to the total mechanical energy if friction is present?