Two friends hold on to a rope, one at each end, on a smooth, frictionless ice su

Question

Two friends hold on to a rope, one at each end, on a smooth, frictionless ice surface. They skate in a circle about an axis through the center of the rope and perpendicular to the ice. The mass of one friend is 75.0 kg and the other has a mass of 125.0 kg. The rope of negligible mass is 4.0 m long and they move at a speed of 4.20 m/s.

http://www.webassign.net/webassignalgphys1/10-p-045.gif

(a) What is the magnitude of the angular momentum of the system comprised of the two friends? kgm^2/s

(b) They now pull on the rope and move closer to each other so that the rope between them is now half as long. Determine the speed with which they move now. m/s

(c) The two friends have to do work in order to move closer to each other. How much work did they do? J

Explanation / Answer

initial angular momentum Li = m1*v*(L/2)+m2*v*(L/2)

Li = 1680 kg m^2 /s

--------------------

b) L2 = m1*v1*(L/4) + m2*v1*(L/4)

L2 = 200V1

L2 = L1

V1 = 1680/200 = 8.4 m/s

-------------

c) W = 0.5*(m1+m2)*(v1^2 - v^2)

Work = 5292 J

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.