Work, Energy and Power- Objective Questions

16. A pump is used to pump a liquid of density? continuously through a pipe of cross-section area A. If a liquid is flowing with speed V, then the power of the pump is?

  • 1/3 ρAv²
  • 1/2 ρAv²
  • 2ρAv²
  • 1/2 ρAv³
Click for Answer/Explanation

1/2 ρAv³

17. A car of mass m has an engine that can deliver power P. The minimum time in which car can be accelerated from rest to a speed v is?

  • mv²/2P
  • Pmv²
  • 2Pmv²
  • mv²P/2
Click for Answer/Explanation

mv²/2P

18. From a waterfall, water is pouring down at the rate of 100 kg/s, on the blades of a turbine. If the height of the fall is 100 m, the power delivered to the turbine is approximately equal to?

  • 100 kW
  • 10 kW
  • 1 kW
  • 100 W
Click for Answer/Explanation

100 kW

19. A particle of mass 200 g is moving in a circle of radius 2 m. The particle is just ‘looping the loop’. The speed of the particle and the tension in the string at the highest point of the circular path are (g = 10 m/s²)-

  • 4 m/s, 5 N
  • 4.47 m/s, zero
  • 2.47 m/s, zero
  • 1 m/s, zero
Click for Answer/Explanation

4.47 m/s, zero

20. A particle of mass 200 gram, is whirled into a vertical circle of radius 80 cm using a massless string. The speed of the particle when the string makes an angle of 60° with the vertical line is 1.5 m/s. The tension in the string at this position is?

  • 1 N
  • 1.56 N
  • 2 N
  • 3 N
Click for Answer/Explanation

1.56 N

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