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ICSE Class 10 Physics Question 21 of 27

Solved 2023 Question Paper ICSE Class 10 Physics — Question 9

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9
Question

Question 6(iii)

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.

Answer

(a) Given,

Initial velocity (vi) = 18 km/h

Converting km/h to m/s

18 x 518\dfrac{5}{18} = 5 m/s

Final velocity (vf) = 54 km/h

Converting km/h to m/s

54 x 518\dfrac{5}{18} = 15 m/s

Work done = Change in kinetic energy = 12\dfrac{1}{2}m(vf2 - vi2)

= 12\dfrac{1}{2} x 120 x (152 - 52)

= 12\dfrac{1}{2} x 120 x (225 - 25)

= 60 x 200 = 12000 J

Hence, work done = 12000J

(b) Power = work donetime\dfrac{\text{work done}}{\text{time}} = 120005\dfrac{12000}{5} = 2400 watt.

Hence, power of engine = 2400 watt.