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**tractive motion, with gradients, Hard questions!!**

4.1 An engine mass of 95 tonnes is hauling a train of mass 750 tonnes along a section of level track. the tractive resistance to motion of the engine is 120 N/tonne and the rolling resistance for the train is 90 N/tonne. initially the engine is travelling at 27 km/hr and then it accelerates over a distance of 1500m.

A) Calculate the power required to achieve this increase in speed?

B)The train then meets a downgrade of 1V in 110H and is brought to a stop in a distance of 900m. calculate the braking force required to stop the train?

4.7 A large truck mass of 35 tonnes is traveling down a gradient of 1V in 60H at a speed of 90 km/hr. The rolling resitance to motion is 115 N tonne.

A) If when the brakes are applied the truck is brought to a stop in 400m what is the applied braking force?

B)How much power is required to provide this braking force?

C)If this same power were available on a uphill gradient of 1 in 60 what constant speed would the truck be capable of reaching?

If u cannot convert km/hr in2 metres per second (ms-1) its (km/hr X 1000) /3600