Q38 of 146 Page 164

Which of the following energy change involves frictional force?

A. Chemical energy to heat energy


B. Kinetic energy to heat energy


C. Potential energy to sound energy


D. Chemical energy to kinetic energy

Heat Energy is the manifestation of the energy in the form of heat and the kinetic energy that it posses due to its motion.

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36

When an object falls freely towards the earth, then its total energy:

A. Increases B. Decreases


C. Remains constant


D. First increases and then decreases

 37

Which one of the following is not the unit of energy?

A. Joule B. Newton-metre


C. Kilowatt D. Kilowatt-hour

 39

Which one of the following statements about power stations is not true?

A. Hydroelectric power stations use water to drive turbines


B. In a power station, turbines drive generators


C. Electricity from thermal power stations differs from that produced in hydroelectric power stations


D. In hydroelectric power stations and thermal power stations, alternators produce electricity.

 40

An electric motor raises a load of 0.2 kg, at a constant speed, through a vertical distance of 3.0 m in 2 s. If the acceleration power stations and thermal power stations, alternators produce electricity

A. 0.3 B. 1.2


C. 3.0 D. 6.0