6. A motor car, of a total mass 1400 kg, running intop gear at 55 km/h, passes on to a rsing gradient of 1 in 20 atthat speed. The road and other resistances may be taken as constantat 270 N/t. With condition unchanged, the speed falls uniformly to40 km/h in a distance of 360 m. An intermediate gear is thenengaged for which the speed ratio between the engine and the roadwheels is 9:1 and the transmission efficiency is 85 per cent. Theengine is then developing a torque of 85 Nm
Determine;
a. The tractive effort before and after the gear change, given thatthe road wheels are 750 mm diameter, [851 N; 1735 kN]
b. The time between the start of retardation and the recovery ofthe original speed of 55 km/h and [36 s]
c. The power being developed by the engine when the car isretarding and accelerating through 50 km/h, given that thetransmission efficiency in top gear is 94 percent.Ă‚Â Ă‚Â Ă‚Â Ă‚Â Ă‚Â Ă‚Â Ă‚Â Ă‚Â [12.56 kW;28.35 kW]
