5.2. Gravitational potential energy and kinetic energy
A subsection of Physics, 9702, through 5. Work, energy and power
Listing 10 of 93 questions
Explain what is meant by gravitational potential energy and by kinetic energy. gravitational potential energy: kinetic energy: A motion sensor is used to measure the velocity of a ball falling vertically towards the ground, as illustrated in . ground motion sensor v A B The ball passes through points A and B as it falls. The ball has a mass of 1.5 kg. The variation with time t of the velocity v of the ball as it falls from A to B is shown in . 8.0 7.0 6.0 5.0 4.0 3.0 0.40 0.60 0.80 v / m s–1 t / s ball at position A ball at position B Use to calculate, for the ball falling from A to B, the displacement, displacement = m the acceleration, acceleration = m s–2 the change in kinetic energy. change in kinetic energy = J Show that the work done by the gravitational field on the ball in as it moves from A to B is equal to the change in kinetic energy.
9702_s16_qp_23
THEORY
2016
Paper 2, Variant 3
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Define velocity. A ball of mass 0.45 kg leaves the edge of a table with a horizontal velocity v, as shown in . ball v table 1.25 m path of ball floor horizontal 1.50 m The height of the table is 1.25 m. The ball travels a distance of 1.50 m horizontally before hitting the floor. Air resistance is negligible. Calculate, for the ball, the horizontal velocity v as it leaves the table, v = m s–1 the velocity just as it hits the floor, magnitude of velocity = m s–1 angle to the horizontal = ° the kinetic energy just as it hits the floor, kinetic energy = J the loss in gravitational potential energy as it falls from the table to the floor. loss in potential energy = J Explain why the kinetic energy of the ball in does not equal the loss of gravitational potential energy in .
9702_s17_qp_22
THEORY
2017
Paper 2, Variant 2
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Explain what is meant by work done. A ball of mass 0.42 kg is dropped from the top of a building. The ball falls from rest through a vertical distance of 78 m to the ground. Air resistance is significant so that the ball reaches constant velocity before hitting the ground. The ball hits the ground with a speed of 23 m s–1. Calculate, for the ball falling from the top of the building to the ground: 1. the decrease in gravitational potential energy decrease in gravitational potential energy = J 2. the increase in kinetic energy. increase in kinetic energy = J Use your answers in to determine the average resistive force acting on the ball as it falls from the top of the building to the ground. average resistive force = N The ball in is dropped at time t = 0 and hits the ground at time t = T. The acceleration of free fall is g. On , sketch a line to show the variation of the acceleration a of the ball with time t from time t = 0 to t = T. T t a g
9702_s20_qp_22
THEORY
2020
Paper 2, Variant 2
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Questions Discovered
93