Category: General Physics
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Work and Kinetic Energy
Two blocks of ice, one four times as heavy as the other, are at rest on a frozen lake. A person pushes each block the same distance d. Ignore friction and assume that an equal force is exerted on each block. A) Which of the following statements is true about the kinetic energy of the heavier…
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Projectile Motion and Conservation of Energy Ranking Task
Six baseball throws are shown below. In each case the baseball is thrown at the same initial speed and from the same height H above the ground. Assume that the effects of air resistance are negligible. Rank these throws according to the speed of the baseball the instant before it hits the ground. Rank from largest…
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Kinetic Energy and Momentum Conceptual Question
The two toy cars shown in the figure, with masses as given in the figure, are ready to race. Both cars begin from rest. For each question, state whether the correct answer is car A, car B, or whether the two cars have equal values for the parameter in question. For the next three parts…
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Torques on a Seesaw: A Tutorial
Learning Goal: To make the connection between intuitive understanding of a seesaw and the standard formalism for torque. This problem deals with the concept of torque, the “twist” that an off-center force applies to a body that tends to make it rotate. Use your intuition to try to answer the following question. If your intuition fails,…
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PhET Tutorial: Masses & Springs
Learning Goal: To understand how the motion and energetics of a weight attached to a vertical spring depend on the mass, the spring constant, and initial conditions. For this tutorial, use the PhET simulation Masses & Springs. You can put a weight on the end of a hanging spring, stretch the spring, and watch the resulting motion.…
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Tactics Box 9.1 Drawing a Before-and-After Visual Overview
Learning Goal: To practice Tactics Box 9.1 Drawing a before-and-after visual overview. During a collision, two objects exert forces on each other that vary in a complex way during the time of the collision. Using Newton’s second law to predict the outcome of a collision would thus be a daunting challenge. Nevertheless, some collisions have very…
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Momentum in an Explosion
A giant “egg” explodes as part of a fireworks display. The egg is at rest before the explosion, and after the explosion, it breaks into two pieces, with the masses indicated in the diagram, traveling in opposite directions. A) What is the momentum PA,i of piece A before the explosion? => PA,i = 0 kg*m/s B) During the…
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Impulse and Momentum Ranking Task
Six automobiles are initially traveling at the indicated velocities. The automobiles have different masses and velocities. The drivers step on the brakes and all automobiles are brought to rest. A) Rank these automobiles based on their momentum before the brakes are applied, from largest to smallest. => B) Rank these automobiles based on the magnitude…