Question:
On complete combustion, a litre of petrol gives off heat equivalent to 3 × 107 J. In a test drive a car weighing 1200 kg, including the mass of driver, runs 15 km per litre while moving with a uniform speed on a surface and air to be uniform, calculate the force of friction acting on the car during the test drive, if the efficiency of the car engine were 0.5.
Solution:
Efficiency of the car engine = 0.5
Energy given by the car with 1 litre of petrol = 1.5 × 107
WD = 1.5 × 107
f = 103 N
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