Work,energy,powerVersion en ligne A brief quiz to test the basics concepts related to work energy and power par Eman Nadeem 1 Which of the following is not termed as work done in physics a A ball falling down from top of a cliff b The patient sitting on the wheel chair being moved by doctor c A vendor pushing the vegetable cart through streets d Striking pen into another pen 2 Which one best defines conservation of energy a The total energy input to a system is equal to the useful energy output b The supply of energy is limited so energy should be conserved c Energy cannot be used faster than created d The total energy in a closed system shall be constant 3 The diagram shows a barrel of weight 2.5 × 103 N on a frictionless slope inclined at 40° to the horizontal. A force is applied to the barrel to move it up the slope at constant speed. The force is parallel to the slope. What is the work done in moving the barrel a distance of 6.0 m up the slope? a 7.2 × 10^3 J b 9.6 × 10^3J c 2.5 × 10^4J d 1.1 × 10^4 J 4 Which of the following is correct a A car drives up a slope at steady speed .The power generated by the engine equals the potential energy gained per unit time b It is impossible for momentum to be conserved in a collision c An electric heater can be 100% efficient d A ball land on ground and bounces is not defined as work done 5 Which row has the correct respective units a b c d 6 To get to his apartment a man has to climb five flights of stairs. The height of each flight is 3.7 m and the man has a mass of 74 kg. What is the approximate gain in the man’s gravitational potential energy during the climb? a 13000J b 2700J c 1300J d 12500J 7 The diagram shows a pump called a hydraulic ram. In one such pump, the long approach pipe holds 700 kg of water. A valve shuts when the speed of this water reaches 3.5 m s-1 and the kinetic energy of this water is used to lift a small quantity of water by a height of 12m. The efficiency of the pump is 20%. Which mass of water could be lifted 12 m? a 6.2kg b 4.6 kg c 7.3kg d 0.24kg 8 The kinetic energy of a car of mass 1000kg is 4.5x10^5J .It is braked with a total constant braking force of 6000N.What will be the stopping distance ? a 75m b 150m c 300m d 37m 9 Which operation involves greatest mean power ? a A car moving against resistive force of 0.4kN at a constant speed of 20m/s b A crane lifting a weight of 3kN at a speed of 2m/s c A crane lifting a weight of 5kN at speed of 1 m/s d A weight being pulled across horizontal surface at speed of 6m/s against a frictional force of 1.5kN 10 An ion is accelerated by a series of electrodes in a vacuum .A graph of the power supplied to the ion against time is plotted .What is represented by the area under the graph between two lines? a The change in kinetic energy of an ion b The average force on the ion c The change in momentum if the ion d The change in velocity of the ion
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