constant speed constant velocity

[tolga]

is there a difference between constant velocity and constant speed when tring to calculate the net force of net frictional forces on a incline plane or just horizontal path?

[/0]

Well... with friction, the direction you move is not important, since friction acts in all directions. So you wouldn't need to use velocity, just speed.

[tolga]

so we can say constant velocity doesn't
makes the net force =0

[/0]

No, if an object is travelling at constant velocity then the net force must be 0.

I think I might have misunderstood your original question since it wasn't that clear...

If you're travelling at constant speed the net force needn't be 0 (e.g. circular motion)

[tolga]

on an inclined plane the net frictional forces aren't zero when its moving with constant velocity do you know the reason for this

[/0]

What do you mean by 'net frictional forces'. Do you mean the frictional forces from every direction surrounding the object?

[tolga]

the question is this kirsty is riding in a bobsled that is sliding down a snow covered hill with a slope at 30degrees to the horizontal. The total mass of the sled aand Kirsty is 100kg. Initially the brakes are on and the sled moves down the hill with a constant velocity.

a)Calculate the net frictional forces acting on the sled?[

[/0]

Ah ok, sorry I was a bit confused before

If you are moving down an inclined plane at constant velocity, the component of gravity acting down the plane balances the frictional force acting up the plane.

i.e.  

[QuantumJG]

is there a difference between constant velocity and constant speed when tring to calculate the net force of net frictional forces on a incline plane or just horizontal path?

Constant velocity and constant speed are not the same thing.

Constant velocity occurs iff net force = 0, whereas constant speed isn't restricted to this since it's a scalar quantity.

An example of constant speed, where the velocity is not constant is UNIFORM circular motion.