im stuck on the assignment: is the potential energy of a marble at the top of a ramp the same as the kinetic energy of the marble at the bottom of the ramp. I don't know the co-efficient of friction of wood but our teacher has told us keywords, they are: PREDICTIONS, measure the length the ball travels after its travelled down the ramp, FINAL VELOCITY and SEARCH DEEPER. so i have no idea what he's talking about, and i think i need to measure final velocity but i don't know how to do this. Also, what do i do after the ball ahs left the ramp? why do i have to measure the distance it travels?? thankyou so much in anticipation!

Question

im stuck on the assignment: is the potential energy of a marble at the top of a ramp the same as the kinetic energy of the marble at the bottom of the ramp. I don't know the co-efficient of friction of wood but our teacher has told us keywords, they are: PREDICTIONS, measure the length the ball travels after its travelled down the ramp, FINAL VELOCITY and SEARCH DEEPER. so i have no idea what he's talking about, and i think i need to measure final velocity but i don't know how to do this. Also, what do i do after the ball ahs left the ramp? why do i have to measure the distance it travels?? thankyou so much in anticipation!

Answer 1

If there is no friction, the KE at the bottom is the same as the PE at the top. But friction is present.

I think I would measure how far the ball traveled. You know the initial PE, so that energy must have went into friction.

Friction is goverened by..

Frictionforce*distance=PEinitial
Now frictionforce on the ramp will be mu*mg*cosTheta, and friction on the horizontal will be mu*mg.

So you need to measure the angle of the ramp, and heightinitial, and the the total distance the ball traveled. Mass will divide out of the friction and PE.

Friction will vary in rolling, so do say five trials, and average them.

Have fun.