physics

How long will it take to heat 3kg of water from 28°C to 88°C in an electric kettle taking 6A from a 220V supply? [specific heat capacity of water = 4180 J kg-1K-1]

A. 120s B. 570s C. 600s D. 836s Correct Answer: Option B B. 570s

6 years ago

The silvered surface in a vacuum flask reduces heat loos due to?

A. conduction B. convection C. radiation D. evaporation Correct Answer: Option C C. radiation

6 years ago

The sagging of overhead electrical cables is the consequence of?

A. linear expansivity B. superficial expansivity C. cubic expansivity D. conductivity Correct Answer: Option A A. linear expansivity

6 years ago

A block and tackle system has six pulleys. a force of 50N applied to it lifts a load of weight W. If the efficiency of the system is 40%, calculate W.

A. 300N B. 200N C. 140N D. 120N Correct Answer: Option D D. 120N

6 years ago

The velocity ratio of an inclined plane, inclines at an angle θ to the horizontal can be expressed as?

A. (sin θ)‾¹ B. sinθ C. (cos θ)‾¹ D. cosθ Correct Answer: Option A A. (sin θ)‾¹

6 years ago

The engine of a train produces a force of 3000N when moving at 30.ms‾¹. calculate the power of the engine

A. 1.00 x 10²W B. 3.00 x 10^4W C. 9.00 x 10^4W D. 3.00 x 10^5W Correct Answer: Option C…

6 years ago

The potential energy in an elastic string of force constant K which has been extended by X metres is expressed as

A. ½kX² B. kX² C. ½kX D. kX Correct Answer: Option A A. ½kX²

6 years ago

Which of the following statements about the mouthpiece of a telephone is correct? It converts sound energy into?

A. acoustic energy B. mechanical energy C. electrical energy D. heat energy Correct Answer: Option C C. electrical energy

6 years ago

A stone of mass 2.0kg is thrown vertically upward with a velocity of 20.0 ms‾¹, calculate the initial kinetic energy of the stone.

A. 200J B. 400J C. 800J D. 1600J Correct Answer: Option B B. 400J Explanation K.E = ½Mv²=12×2×20² = 400J

6 years ago

Which of the following source of energy is renewable?

A. petroleum B. charcoal C. hydro D. nuclear Correct Answer: Option C C. hydro

6 years ago
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