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Old Sep 30th 2010, 01:22 PM   #1
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Join Date: Sep 2010
Posts: 7
Working out power.

Ive been given a question about power. Weve done it at school and im revising it at home before next lesson. I hope you can help me. Im really confused.

The infomation that I am given is;

Model: BMW 3 series, Diesel, 2 litre engine
Top speed: 204Km/h
0 - 100Km/h: 10.6 seconds
Max Power: 90 Kw
Mass: 1655Kg (Including 150kg passengers)

I know the method on how to solve this but I cannot do one of the calculations. The calculation that im stuggling with is finding out the Velocity.

All I can think of doing is:

0 - 100 Km/h in 10.6 seconds.
= 0 - 100,000m/h in 10.6 seconds
= 0 - 27.78m/s in 10.6 seconds
27.78 divided by 10.6 = 2.62m/s/s

But with this answer when I use it in the formula for acceleration, it doesnt give me the same value my teacher worked out. I could be doing this completly wrong. Please help.

Many thanks

Steve
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Old Sep 30th 2010, 03:52 PM   #2
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Location: Lithuania
Posts: 105
Please write your formula and how you use it.
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Old Oct 1st 2010, 07:36 AM   #3
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Ohhh Ive figured it out.

After you find velocity i use.

a = (V - U) divided by Time

then

Force = Mass X Acceleration

Work done = Force X Distance

Distance = (U + V) Divided by 2 X Time

Power = Work done Divided by Time
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Old Oct 2nd 2010, 07:27 AM   #4
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Location: PAKISTAN
Posts: 79
Hello steve, u seems to be doing correct,except may be some calculator error, if i m not wrong. i suppose. Are you using calculator for calculating distance,i.e. take care of the calculation again.
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