The electric motor of a model train accelerates the train from rest to 0.520 m/s

Question

The electric motor of a model train accelerates the train from rest to 0.520 m/s in 20.0 ms. The total mass of the train is 625 g. Find the average power delivered to the train during its acceleration. A ski jumper starts from rest 59.5 m above the ground on a frictionless track and flies off the track at an angle of 45.0 above the horizontal and at a height of 20.0 m above the ground. Neglect air resistance. What is her speed when she leaves the track? What is the maximum altitude she attains after leaving the track? Where does she land relative to the end of the track?

Explanation / Answer

5)

m = 625 g = 0.625 Kg
t = 20 ms = 0.02 s

Power = work done / time

work done = change in kinetic energy

so,
Power = change in kinetic energy / time
= (0.5*m*vf^2 - 0.5*m*vi^2) / time
= (0.5*0.625*0.52^2 - 0.5*0.625*0^2) / 0.02
= 0.0845/0.02
= 4.225 W
Answer: 4.225 W

we are allowed to asnwer only 1 question at a time

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