Subject
Physics study guides
Forces, energy, motion, and waves — explained with the math worked out and the concept made visual.
4 explained questions, each with the answer, a worked explanation, and something interactive to help it stick.
- Which of these is exhibiting kinetic energy?The object that is moving is exhibiting kinetic energy, the energy of motion, such as a rolling ball, a running person, or falling water. Stationary or stored-energy examples show potential energy, not kinetic energy.Read the guide
- Is swinging a tennis racket against a ball an example of a third-class lever?True. In a tennis swing the elbow acts as the fulcrum, the forearm muscles apply effort between the elbow and the hand, and the ball is the load at the far end. Because the effort sits between the fulcrum and the load, it is a third-class lever.Read the guide
- Force Acting Over a Distance Is the Definition of What?Work. In physics, work is defined as a force acting over a distance: W = F x d, or W = Fd cos theta when the force is at an angle to the displacement. Work is measured in joules (J), where one joule equals one newton-metre.Read the guide
- The Impulse-Momentum Relationship Is a Direct Result of What?The impulse-momentum relationship is a direct result of Newton's second law of motion. Because force equals the rate of change of momentum (F = Δp/Δt), multiplying both sides by time gives impulse: FΔt = Δp, so impulse equals the change in momentum.Read the guide