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# Physics-Work and Power-Help Please? Thanks!?

Could someone help me with this problem. Please explain what equation I should use and how I go about solving it. I don't know how to do it. It would be greatly appreciated. Thanks!

1.) A 1500kg car accelerates uniformly from rest to 10m/s in 3 secs.

a.) What is the work done on the car in this time period?

b) What is the power delivered by the engine in this time period?

Thanks again! 10 Points Available!!!!

### 2 Answers

- Charles MLv 61 decade agoFavorite Answer
a. Calculate work. Work is the the amount of energy transferred by a force, done over a net distance.

F = ma

W = Fd, d is the distance or in this case since we can but don't want to calculate the distance

W = 1/2 * mv^2

Plug in the numbers:

W = 1/2 * 1500kg (10m/s)(10m/s)

Work = 75 kJ

b. Calculate the power. Power is the rate at which work is done, so this will be in units per second.

P = W / t

P = 75 kJ / 3s

P = 25 kW

- ukmudgalLv 61 decade ago
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Mass of car = 1500 kg

Initial velocity = u = 0

Final velocity = v = 10m/s

time = t = 3 s

Work done on a body equals increases its kinetic energy

Initial kinetic energy =KEi=(1/2)mu^2=zero

Final kinetic energy =KEf=(1/2)mv^2=0.5*1500*( 10 )^2=75000 J

Increase in kinetic energy =KEf - KEi =75000 J

Work done on a body = increase in kinetic energy=75000 J

a)the work done on the car in 3 second is 75000 J

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Power = work / time =75000 /3 =25000 watt = 25 kW

b) The power delivered by the engine in 3 second is 25000 W or 26 kW

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