- #1
srnj222
- 8
- 0
I'm having trouble with these two "classic meter stick problems"
1: A rod of length L and mass M stands vertically on a flat frictionless surface. A wad of putty of mass m and initial velocity v strikes the stick at a right angle at height 3/4 L. The collision is perfectly inelastic. Find the translational and rotational motions of the object.
2: A meter stick stands vertically at rest on a frictionless level surface. If it falls, what angular velocity will it have when it contacts the floor?
Heres what I've got, not sure where to go from here:
1: Momentum Initial = mv
Momentum final = (m+M)vf
L = mV x r = I w
Dont know what to do with the equations
2: I assumed a and alpha were constant, don't know if they are:
a = L/t^2 alpha = pi/t^2 L/a = pi/alpha
L w=pi v
w = pi * v / L
mg(L/2) = 1/2 mv^2 + 1/2 I w^2 >> I = 1/12 mR^2
gL = v^2 + 1/12L^2(pi * v/L)^2
v = (pi/L)sqrt(gL/(1+pi/12))
1: A rod of length L and mass M stands vertically on a flat frictionless surface. A wad of putty of mass m and initial velocity v strikes the stick at a right angle at height 3/4 L. The collision is perfectly inelastic. Find the translational and rotational motions of the object.
2: A meter stick stands vertically at rest on a frictionless level surface. If it falls, what angular velocity will it have when it contacts the floor?
Heres what I've got, not sure where to go from here:
1: Momentum Initial = mv
Momentum final = (m+M)vf
L = mV x r = I w
Dont know what to do with the equations
2: I assumed a and alpha were constant, don't know if they are:
a = L/t^2 alpha = pi/t^2 L/a = pi/alpha
L w=pi v
w = pi * v / L
mg(L/2) = 1/2 mv^2 + 1/2 I w^2 >> I = 1/12 mR^2
gL = v^2 + 1/12L^2(pi * v/L)^2
v = (pi/L)sqrt(gL/(1+pi/12))
Last edited: