Rigid-Body Work and Energy - Example Problem 8.5-2

 

Consider a 5-kg disk rolling to the right under the influence of (a) a pulling force (P = 10 N) and (b) a moment (M = 10 N-m). Assume that the disk does not slip relative to the ground and that the coefficient of static friction is μ_s = 0.45. The disk has a radius of 1.0 m. If the disk starts from rest, determine, in each case, the velocity of the disk's mass center after it has moved 5 m.

 

 

Given:

• Disk
• r = 1 m
• m = 5 kg
• P = 10 N
• M = 10 N-m
• v_G1 = 0
• Δs_G = 5 m
• μ_s = 0.45
• no slip
• state 1 = starts from rest
• state 2 = after the disk has moved 5 m

 

Find:

• v_G2

 

Video solution:

 

The following video walks you through the solution to this problem. It is suggested that you try solving the problem first and then, if you have difficulties with the solution, watch the video for help.

 

 

Interactive solution:

 

Draw a free-body diagram for each case. Click on the figure to reveal the solution.

 

Which of the forces/moments, that act on the disk, do work?

 

N
F_fs
mg
P
M