Physics homework 2

# Physics homework 2 - 80 A jet circling the airport at a...

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80) A jet circling the airport at a constant speed is not going to be changing kinetic energy in the sense that the energy from the gasoline inside the plane’s gas tank will be converted from potential energy to kinetic as it burns, conversely the kinetic energy that is present as a result of the fuel burning will be lost as heat energy from the aircraft. The jets momentum should remain constant throughout 81) You would have to know the height of the rack 82) If the object has a velocity towards the south the kinetic energy will increase as the force is acted upon it towards the north because whatever this force was, was being converted from potential into kinetic as it acts upon the car., 83) The kinetic energy would increase but the momentum would change and slow down. 85) No it is not possible to change an objects momentum without changing kinetic energy. Because with any change in velocity there must be a change in energy. 86) The only thing I can think of is that the professor never specified that they were in an area with a gravitational pull. Perhaps the ball was strapped to a shelf in space, granted I am being extremely creative right now, but I can’t think of something else. 88) The gravitational potential energy of the pendulum is greatest at the height of it’s swing, and the kinetic is greatest as it reaches the bottom of its arc. 89) Because energy cannot be created or destroyed. Therefore if the energy at the top ignoring friction could never be greater than at the bottom. 90) If friction is present, then on consecutive swings the height is going to lessen. An object can never swing as high as the place at which it starts because of friction and air resistance. 91) Both balls will sustain the same impulse, though one bounces higher, the other is transferring its energy into the floor which absorbs this energy and converts it into potential energy, and perhaps some reverberation and sound. 93) When dribbling a ball, the momentum changes when it begins to fall. The ball is being pushed by a human hand/arm the energy from the arm changes from potential to kinetic as the arm begins to move. The ball has a force exerted on it combining the gravitational potential energy and the kinetic energy from the hand pushing the ball towards the floor. The ball begins to increase speed until it hits the floor, slows down, and the potential energy in the floor and the elasticity of the ball acts upon it. This energy is converted into kinetic and the ball begins to accelerate in the opposite direction. 94) When a rifle is fired, there is an elastic relationship. For every action there is an equal

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Physics homework 2 - 80 A jet circling the airport at a...

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