Center of Circle - General Physics - Solved Past Paper, Exams of Physics

Download Center of Circle - General Physics - Solved Past Paper and more Exams Physics in PDF only on Docsity! 1. (25 pts) a) (5 pts) As the rubber chicken swings in a circle at the end of a rope, in what direction is the force exerted on the chicken by the rope? The force exerted on the chicken must be towards the center of the circle. b) (5 pts) You calculate the work done by a force exerted on an object as it moves. The answer is negative. What does this mean, in terms of the energy of the object? A negative work indicates energy is being removed from the system. Thus the energy of the object decreases. c) (5 pts) Does a force actually have to be the cause of an object’s motion in order to do work on the object? Explain. No, the force need not be the cause of the motion. As long as the force acts on the object, and the object does move, the force does work. For example, kinetic friction does not make an object move. Rather it makes the object stop moving! Yet it does work. On the other hand, the force of the string on the chicken in part (a) is what causes the motion to be circular, yet it does no work! d) (5 pts) A skier is pulled at a constant speed up a snow-covered hillside inclined at 30◦ by a rope that is parallel to the surface of the hill. What angle would you use when calculating the power necessary to perform this feat? (P = ~F · ~v). Both the force and the motion are up the hill. Thus ~F and ~v are parallel. Since the angle in the dot product is the angle between the two vectors, you would use an angle of zero here. e) (5 pts) Can a person experience weightlessness in the presence of a gravitational force? (i.e. is it possible for a person that is on or near the Earth to experience the sensation of weightlessness?) Explain. It is possible. Since the sensation of weight comes from the force supporting your body against gravity (rather than from the gravitational force itself), all that is needed for a weightless sensation is the lack of a supporting force. If you jump out of a plane, the floor of the plane no longer supports you against gravity and you fall. While there is a gravitational force acting on you (pulling you towards the Earth), you feel weightless.