Answer :
The average power delivered to the train during its acceleration is 0.3 W
Initial velocity (u) = 0 m/s
Final velocity (v) = 0.620 m/s
Time interval (Δt)= 21.0 milisecond
Mass of train (m) = 875g
Power is defined as the work done for a specific time period or it is also the rate of doing work.
so we can also write power as :
Power (P) = work done (W)/ time interval (Δt)
Work done is defined as the dot product of the force acted on an object and the distance travelled by the object on the application of that force.
Work done (W) = force(f) × distance (s)
F = m × a (from the newton’s second law of motion)
We have learnt from the 2nd equation of motion that :
a = (v-u)/t
distance (s) = average velocity / time
= (0.620 ×1000 )/ (2 × 21 )
=14.76 m
Substituting the value of force into the expression of work
P =( m × a × s )/ t
= (875 × 620 × 14.76 )/(1000 × 1000 × 21)
P = 0.3 W
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