Guided Reading Chapter 2 PDF

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Chapter 2.3: Bumper Cars Vocabulary (short definition/use in a sentence) •

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Linear Momentum o The measure of an object’s translational impetus or tenacity o Its determination to keep moving the way it is currently moving Impulse o How momentum is transferred, the force exerted on an object for a certain amount of time Angular Momentum o Measure of an object’s rotational impetus or tenacity o Its determination to keep rotating the way it is currently rotating Angular Impulse o A torque exerted on an object for a certain amount of time Conserved quantity Gradient o Characterizes how some physical quantity changes gradually with position

Units (what quantity is measured in the following) • • •

Kilogram-meter per second (kg m/s): o Unit of momentum Newton second (Ns): o Unit of impulse Kilogram-meter squared per second (kg m2/s o Unit of angular momentum

Equations and physical laws (express in words) •

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Linear Momentum o Momentum = mass x velocity o p = m*v Impulse o Impulse = force x time Angular Momentum o Angular momentum = rotational mass x angular velocity Angular Impulse o Angular impulse = torque x time

Example problems/questions: 1. If a 1000kg car is traveling 50 mph (coasting on ice – so no friction), how many .1g bugs who are stationary does it need to hit to slow down to 1 mph? a. The car’s kinetic energy is 500,000 kg m^2/s^2, so 5,000,000 .1g bugs would be able to bring the car to 1 mph.

2. More bowling! When you first let go of the ball, it is not rotating and skids down the alley. a. What happens to its kinetic energy as it skids? i. Friction between the ball and the bowling alley creates energy in the form of heat, which means that there is less kinetic energy. b. The ball will start to rotate – what provides the torque that starts that rotation? i. Friction provides the torque that keeps the ball rotating, because eventually the ball stops skidding and starts rolling c. When the ball strikes the pins, the pins go flying *and* the ball continues moving forward. Why doesn’t the ball bounce off the pins? i. The mass of the ball is much greater than the mass of the pins, so even though the pins push back on the ball with an equal and opposite force the ball continues to move forward....