Class 9 Work and Energy Quiz set 1 1. The speed of a motor car becomes six times, then the kinetic energy becomes 12 times 36 times 6 times 24 times 2. A body is thrown vertically up from the earh′s surface. What happened to its P.E. during the motion ? decreases first decreases then increases increases remains constant 3. The mass of an object P is double the mass of Q. If both move with the same velocity, then the ratio of K.E. of P to that of Q is 2 : 1 1 : 4 4 : 1 1 : 2 4. Work done upon a body is always negative a vector quantity a scalar quantity always positive 5. When the momentum of a body decreases 10%, its K.E. decreases by 20% none of these 36% 40% 6. Two unequal masses posses the momentum, then the kinetic energy of the heavier mass is ………… the kinetic energy of the lighter mass. much greater than smaller than same as greater than 7. Two unequal masses posses the same K.E. Then, the heavier mass has Smaller momentum Greater momentum Greater speed The same momentum as the lighter mass 8. No work is said to have been done when an object moves’ at an angle of ……….. with the direction of the force. 0° 45° 90° 180° 9. The number of joules contained in 1 kWh is 36 x 10⁴ 3.6 x 10⁶ 36 x 10³ 36 x 10² 10. The work done in lifting a mass of 1 kg to a height of 9.8 m is 1 J (9.8)² none of these 9.8 J 11. The K.E. of a body in increased most, by doubling its weight density mass speed 12. A body of mass 20 kg is dropped from a height of 2m. If ‘g’ is taken to be equal to 10 m/s², the Kinetic energy of the body, just before striking the ground, will be none of these 40 J 4 J 400 J 13. A ball of mass 200 g fall form height of 5 m. what is its K.E. when it just reaches the ground ? 980 J none of these 98 J 9.8 J 14. 1 hp is equal to 74.6 kW 0,746 kW 746 kW 7.46 kW 15. A stretched string possesses _______ energy. elastic potential electric Kinetic magnetic Loading … Question 1 of 15

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