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

Question

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!!!!

Answer 1

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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

Answer 2

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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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