A1100 kg car starts from rest on a horizontal road and gains a speed of 89 km/h in 35 s. (a) what is its kinetic energy at the end of the 35 s? (b) what is the average power required of the car during the 35 s interval? (c) what is the instantaneous power at the end of the 35 s interval, assuming that the acceleration is constant?

The answers are given below;

a) 336093,12

b) 9602,66

c) 9602,66

Explanation:

First let's start making 89 km/h to m/s. To do this;

a ) Now let's find its kinetic energy; As we know kinetic energy formula is

Car's kinetic energy after 35 seconds is:

b ) Because the road is horizontal it is a fact that W(work) = Δ

Therefore the average power required is;

P(Power) = and;

c ) Instantaneous power can be calculated as:

Now, since we assume that acceleration is constant, we can use the formula x = V.t to find x(distance). Then we can find F as we know W=F.x

and

→  

therefore the instantaneous power at the end of 35 seconds is:

0.19 m/s and 0.45 m/s

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