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Unformatted text preview: Which of the following is the better explanation of what drives a rocket forward? (A) The rocket and propellant function as an isolated system. When the propellant leaves the nozzle it has momentum, and the rocket receives an impulse in the direction opposite the exhaust. (B) The exhaust gases push against the air, driving the rocket forward. Types of energy 1. Kinetic energy (K): motional energy m p mv K 2 2 1 2 2 = = 2. Potential Energy (V): position energy 3. Internal Energy (U): “hidden” energy Note: Energy is a scalar quantity with units of Joules Can the kinetic energy of a particle be negative? Can the change of a particle’s kinetic energy be negative? Calculate the kinetic energy, in Joules, of a 200gram ball moving at a speed of 30 m/s. J 90 m/s) kg)(30 2 . ( 2 1 2 1 2 2 = = = mv K I J = 1 kg∙m 2 /s 2 E = K + V + U SYSTEM ENVIRONMENT Energy transfer The Basic Energy Model If the system is isolated, then there is no change in its total energy. We can then write U V K E ∆ + ∆ + ∆ = = ∆ This is the law of conservation of energy. Abigail, standing on a thirdfloor balcony, holds a 0.20kg apple 10 meters Abigail, standing on a thirdfloor balcony, holds a 0....
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This note was uploaded on 04/17/2008 for the course PHYS 120 taught by Professor Decarlo during the Spring '08 term at DePauw.
 Spring '08
 DeCarlo
 Physics, Momentum

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