Power, velocity and frictional resistance

In summary, power is a measure of the rate at which work is done or energy is transferred and is directly proportional to velocity. Frictional resistance can slow down an object's velocity by converting some of its kinetic energy into heat or sound energy. The amount of frictional resistance an object experiences is affected by the type of surface it is moving on, the weight of the object, and any external forces acting on it. Power can be used to overcome frictional resistance, which is why machines and vehicles are designed with powerful engines or motors. The steeper the incline, the more power is needed to overcome frictional resistance due to the increased force of gravity pulling the object down.
  • #1
Darth Frodo
212
1

Homework Statement


(a) A car of mass 1365kg has 60kW engine and a max speed of 145km/hr. Find the frictional resistance.

(b) Calculate max speed of car up a gradient of 1 in 5 if Friction stays the same.

Homework Equations



P = F.v

The Attempt at a Solution



60000 = F (40.2m/s)
F = 149205 N


(b) P = netF . V
60000 = (1492.5 + mgsinθ)
θ = angle of inclination
60000 = [1492.5 + (1365)(9.8)(1/[itex]\sqrt{26}[/itex])]V
v = 60000/4118.6 = 14056 m/s


Is this correct?
 
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  • #2
It looks good to me!

The question isn't quite right; friction will not remain the same as the speed changes.
 

1. What is power and how is it related to velocity?

Power is a measure of the rate at which work is done or energy is transferred. It is directly proportional to velocity, meaning that the higher the velocity, the greater the power.

2. How does frictional resistance affect an object's velocity?

Frictional resistance is a force that opposes the motion of an object. It can slow down an object's velocity by converting some of its kinetic energy into heat or sound energy.

3. What factors affect the amount of frictional resistance an object experiences?

The amount of frictional resistance an object experiences is affected by the type of surface it is moving on, the weight of the object, and any external forces acting on the object.

4. Can power be used to overcome frictional resistance?

Yes, power can be used to overcome frictional resistance. This is why machines and vehicles are designed with powerful engines or motors, to generate enough power to overcome the resistance and maintain a constant velocity.

5. How does the angle of an incline affect the power needed to overcome frictional resistance?

The steeper the incline, the more power is needed to overcome frictional resistance. This is because the force of gravity pulling the object down the incline increases with the angle, making it harder to move against it.

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