physics help 4 please!
posted by kelsey on .
A solid disk (mass = 1 kg, R=0.5 m) is rolling across a table with a translational speed of 9 m/s.
a.) What must the angular speed of the disk be?
b.) What is the rotational KE of the disk?
c.) What is the total KE of the disk?
d.) The disk then rolls up a hill of height 2 m, where the ground again levels out. Find the translational and rotational speeds now.
I will be happy to critique your thinking.
The angular speed is w = V/R
I = moment of inertia = (1/2) M R^2
KE(rotational) = (1/2) I w^2
= (1/2)(1/2)M R^2(V/R)^2
= (1/4) M V^2
KE(ranslational) = (1/2) M V^2
Add the two KE types for total KE
Get to know these formulas. Others should not have to refresh your memory and do the work for oyu
For some reason everytime I try to calculate the KE rotational I do not get the right answer. The translational speed can be used for V, right?