Physics
A car of mass 120 kg is moving at a speed 18 km/h and it accelerates to attain a speed of 54 km/h in 5 seconds. Calculate:
(a) the work done by the engine.
(b) the power of the engine.
Work, Energy & Power
ICSE 2023
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Answer
(a) Given,
Initial velocity (vi) = 18 km/h
Converting km/h to m/s
18 x = 5 m/s
Final velocity (vf) = 54 km/h
Converting km/h to m/s
54 x = 15 m/s
Work done = Change in kinetic energy = m(vf2 - vi2)
= x 120 x (152 - 52)
= x 120 x (225 - 25)
= 60 x 200 = 12000 J
Hence, work done = 12000J
(b) Power = = = 2400 watt.
Hence, power of engine = 2400 watt.
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