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3 years ago

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Question 4 A car of mass 820 kg has a maximum power of 30 kW and moves against a constant resistance of motion to 910 N. Calcula

te the maximum speed of the car in the following situation; b)Up an incline (hill) of 8.75° to the horizontal?

1 answer:

wolverine [178]3 years ago

7 0

Answer:

P = W / t = m g s / t = m g v where work by auto = m g s

30 kw = 30000 watts = 30000 J / s

Work wasted = F v as shown above relating work and power

Work done against incline = m g s sin 8.75 and power against incline

= m g v sin 8.75 = 1222 v Joules / sec

power in moving auto = power available - power lost to friction

power in moving auto = 30000 - resistance = 30000 - 910 v

1222 v = 30000 - 910 v

v = 30000 / 2132 = 14 m/s

Note: constant resistance to motion must mean P = W / t = F s / t = F v

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