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Power as it relates to constant velocity but increasing speed

by student1984
Tags: constant, force, instantaneous power, power, velocity
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student1984
#1
Nov1-11, 06:05 PM
P: 1
the questions I have are general questions regarding power and velocity

here are some relevant equations:
P=Fv

a) if the force required to keep an object in motion with a constant velocity does not depend on the speed of the object, does the power required to keep the object moving in at a constant velocity increase, decrease or remain the same with increasing speed?

b) in actuality, the force required to keep a car moving with a constant velocity increases in magnitude with the square of the car's speed. Does the power required to keep the car moving with a constant velocity increase, decrease or remain the same with increasing speed? How does this result compare with the answer to question a?

I'm assuming from that answer to part a is REMAIN THE SAME and part b is INCREASES WITH INCREASING SPEED.

am i correct in my assumptions?
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Redbelly98
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Nov1-11, 07:05 PM
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Welcome to Physics Forums.
Quote Quote by student1984 View Post
the questions I have are general questions regarding power and velocity

here are some relevant equations:
P=Fv

a) if the force required to keep an object in motion with a constant velocity does not depend on the speed of the object, does the power required to keep the object moving in at a constant velocity increase, decrease or remain the same with increasing speed?

b) in actuality, the force required to keep a car moving with a constant velocity increases in magnitude with the square of the car's speed. Does the power required to keep the car moving with a constant velocity increase, decrease or remain the same with increasing speed? How does this result compare with the answer to question a?

I'm assuming from that answer to part a is REMAIN THE SAME and part b is INCREASES WITH INCREASING SPEED.

am i correct in my assumptions?
If the velocity is constant, then the speed must be constant also. (The velocity's magnitude and direction are both constant; speed is the magnitude of velocity, hence it is constant.)


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