I can't even do the first question of my mechanics homework, which is to do with power:
A truck of mass 2800kg is accelerating along a straight road at 2.5 m s-2
I think that the force developed by the engine is 8200 Newtons. Is this the same as the power, or not?
Power and Force are not the same thing.
Power is the rate at which work is done.
Power, for constant forces, is calculated using
providing that the velocity is in the same direction as the force.
To analyse this problem, draw a diagram:
Applying Newton's 2nd Law ("F=ma") gives
F - 1200 = 2800×2.5
from which F = 8200
In your case, the Force is indeed 8200N.
To work out the power, multiply by the velocity of 10 m/s to give 82000 Watts, or 82kW
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We know "Work Done = Force × Distance", or
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