Impulse delivered to a sphere: Rotation motion (momentum) question

In summary, we are given a sphere of radius R and mass M sitting on a horizontal tabletop. A horizontally directed impulse with magnitude J is delivered to a spot on the ball a vertical distance h above the tabletop. We are asked to determine the angular and translational velocity of the sphere just after the impulse is delivered for three different cases: when h > R, h < R, and h = R. Using the equations p = mv for linear momentum and L = r x p (r 'cross' p) for angular momentum, we can solve for the values of v and \omega for each case. The final answers are: h > R, v = 0, \omega = J/I; h < R, v =
  • #1
boaty
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Homework Statement


A sphere of radius R and mass M sits on a horizontal tabletop. A horizontally directed impulse with magnitude J is delivered to a spot on the ball a vertical distance h above the tabletop.

Part 1:
Determine the angular and translational velocity of the sphere just after the impulse is delivered when...
h > R, v = ?, [tex]\omega[/tex] = ?
h < R, v = ?, [tex]\omega[/tex] = ?
h = R, v = ?, [tex]\omega[/tex] = ?

Homework Equations


Since we're dealing with momentum, p = mv for linear momentum and L = r x p (r 'cross' p) for angular. Also, since the rotation of the sphere takes place around its axis of symmetry, L = I[tex]\omega[/tex] can be used.

The Attempt at a Solution


I know when h = R, v = J/m and [tex]\omega[/tex] = 0. Other than that I have no idea where to start. The help which goes with the problem said J = JT + JR, where the former is translational impulse, the latter, angular, but using these equations I can't get any answers (I can't even get the obvious answer I stated above).

Thanks in advance.

Edit:
I just figured out how to hack the website to give me the answer, so I don't really need help anymore. Usually the questions on the site are way more difficult than the in-class/exam questions, but if anyone still wants to post a solution, feel free. At least the question will be archived with an answer then.
 
Last edited:
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  • #2
Answer (for anyone who needs it):h > R, v = 0, \omega = J/Ih < R, v = J/m, \omega = 0h = R, v = J/m, \omega = 0
 

1. What is impulse?

Impulse is the change in momentum of an object. It is equal to the force applied to an object multiplied by the time it is applied.

2. How is impulse related to rotation motion?

In rotation motion, the impulse delivered to a sphere causes a change in its angular momentum. This is because the force applied to the sphere causes it to rotate, and the longer the force is applied, the greater the change in angular momentum.

3. What is the formula for calculating impulse delivered to a sphere?

The formula for impulse delivered to a sphere is given by: I = F * Δt, where I is the impulse, F is the applied force, and Δt is the time the force is applied.

4. How does the mass of the sphere affect the impulse delivered?

The mass of the sphere does not directly affect the impulse delivered. However, it does affect the resulting change in momentum, as a heavier sphere will require a greater force and/or longer time to achieve the same change in momentum as a lighter sphere.

5. Can you explain the concept of conservation of momentum in relation to impulse delivered to a sphere?

Conservation of momentum states that the total momentum of a system remains constant, unless acted upon by an external force. In the case of a sphere, the impulse delivered by an external force will result in a change in its momentum. However, the total momentum of the system (the sphere and the object applying the force) will remain constant, as the change in the sphere's momentum will be equal and opposite to the change in the object's momentum. This is known as the law of action and reaction.

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