How is Work and Power Calculated in These Scenarios?

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In the discussion, participants analyze the calculation of work and power in two scenarios involving friction and constant velocity. For the first scenario, a box with a mass of 20 kg experiences a frictional force of 49 N while being pulled over 10 m, leading to the conclusion that the work done is zero due to constant velocity. In the second scenario, a car with a mass of 1500 kg moving at a constant speed of 5 m/s faces a frictional force of 1000 N, prompting calculations for the engine's power output. The participants are encouraged to solve the problems independently before discussing the answers. The thread emphasizes understanding the principles of work and power in physics.
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1) A box of 20 kg mass is pulled by force F with constant velocity on a horizontal surface. If force of friction is 49N, work done during displacement of 10m is ________ J.

(a) 490
(b) 245
(c) 980
(d) zero

W=Fxs
W= change in kinetic energy
W=0 (constant velocity)


Which equation will be used?

2) Engine of a car of mass 1500 kg keeps car moving with constant velocity 5m/s. If frictional force is 1000 N, power of engine is ____________
(a) 5 kW
(b) 7.5 kW
(c) 15 kW
(d) 75 kW

p=mv (momentum)

Which answer in the above question?

Please reply as early as possible.

Pranav
 
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