Solving for Max Height and Angular Velocity of a Thin Rod

In summary, the conversation discussed the problem of finding the maximum height reached by the centre of mass and the angular velocity of rotation about the centre of mass of a thin rod that is suspended horizontally and experiences an impulse vertically upwards at one end. While attempting to solve the problem, it was noted that there may be missing data, specifically the magnitude of the impulse.
  • #1
albega
75
0

Homework Statement


A thin rod of length L, mass m is suspended horizontally at rest. It is suddenly released and experiences immediately after an impulse vertically upwards at one end.

I need to find the maximum height reached by the centre of mass and the angular velocity of rotation about the centre of mass.

The Attempt at a Solution


I can't see how there is enough information given in the question. I have used the fact that J=0.5Lp here (J is angular momentum) from the relation between angular and linear impulse, and then this means 0.5Lmv=Iω, with I=mL2/12. Then 0.5Lmv=mL2ω/12. This relates v and ω by v=ωL/6. I could then probably work with constant acceleration formulae to get the answer, however both v and ω are unknowns (and I have to find ω in the next part) so I have no idea where to go.

Thanks in advance :)
 
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  • #2
The initial velocity of CM ,angular velocity of the rod and the maximum height reached all depend upon the magnitude of impulse . So surely some data is missing from the question.
 
  • #3
Tanya Sharma said:
The initial velocity of CM ,angular velocity of the rod and the maximum height reached all depend upon the magnitude of impulse . So surely some data is missing from the question.

Yes, as I suspected. Thanks for clarifying.
 
  • #4
Well to me it looks as thought OP isn't supposed to solve for a number, but max height as a function of I.
 
  • #5
albega said:

Homework Statement


A thin rod of length L, mass m is suspended horizontally at rest.

Length L, mass M, impulse, I...
 
  • #6
BiGyElLoWhAt said:
Length L, mass M, impulse, I...

Except that no label is given for the impulse in the question as stated in the OP - that's what's missing.
 

1. What is the equation for calculating the maximum height of a thin rod?

The equation for calculating the maximum height of a thin rod is h = (v02sin2θ)/2g, where h is the maximum height, v0 is the initial velocity, θ is the launch angle, and g is the acceleration due to gravity.

2. How do you determine the initial velocity of a thin rod?

The initial velocity of a thin rod can be determined by using the equation v0 = h/(sinθ√(2/g)), where h is the maximum height, θ is the launch angle, and g is the acceleration due to gravity.

3. What is the formula for finding the angular velocity of a thin rod?

The formula for finding the angular velocity of a thin rod is ω = v0/r, where ω is the angular velocity, v0 is the initial velocity, and r is the radius of the thin rod.

4. Can the maximum height of a thin rod be calculated without knowing the launch angle?

No, the launch angle is a crucial component in calculating the maximum height of a thin rod. Without this information, the maximum height cannot be accurately determined.

5. How does air resistance affect the maximum height and angular velocity of a thin rod?

Air resistance can reduce the maximum height and angular velocity of a thin rod by applying a force in the opposite direction of the motion. This can decrease the overall velocity and distance the rod can travel, resulting in a lower maximum height and angular velocity.

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