- #1

FrogPad

- 810

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Ok, I'm really lost here. I guess I do not understand the equations well enough to think on my own in this question :)

So the question is as follows:

Two simple pendulums of equal length are suspended from the same point. The pendulum bobs are point like masses. m1 > m2. The more massive bob (m1) is initially drawn back at an angle of 40^(degrees) from vertical. After m1 is released what is:

1. Find the speed of m1 just before the collision.

2. Determine the maximum angle to which the masses swing after the collision.

3. How much energy is lost during the collision?

Ok, I understand how to do 1 and 2. But I have no idea what to do with question 3.

To make things easier let's assume the folllowing variables have been derived or are known:

m1

m2

v_1i : initial velocity of pendulum swinging towards the stationary bob

v_1f : the velocity of the larger bob after the collision

v_2i : = 0... since the lower-mass-bob is not moving

v_2f : the velocity of the smaller bob after the collision

Any suggestion on how to handle the loss in kinetic energy would be fantastic... thank you.

EDIT: Ok thinking about this... I think I might understand the question now.

Initial Kinetic Energy:

[tex]

KE_i = \frac{1}{2}m_1(v_{1i})^2 + \frac{1}{2}m_2(0)^2

[/tex]

[tex]

KE_f = \frac{1}{2}(v_{1f})^2 + \frac{1}{2}m_2(v_{2f})^2

[/tex]

So the loss of kinetic is [tex] KE_f - KE_i [/tex] ...? right? :)

So the question is as follows:

Two simple pendulums of equal length are suspended from the same point. The pendulum bobs are point like masses. m1 > m2. The more massive bob (m1) is initially drawn back at an angle of 40^(degrees) from vertical. After m1 is released what is:

1. Find the speed of m1 just before the collision.

2. Determine the maximum angle to which the masses swing after the collision.

3. How much energy is lost during the collision?

Ok, I understand how to do 1 and 2. But I have no idea what to do with question 3.

To make things easier let's assume the folllowing variables have been derived or are known:

m1

m2

v_1i : initial velocity of pendulum swinging towards the stationary bob

v_1f : the velocity of the larger bob after the collision

v_2i : = 0... since the lower-mass-bob is not moving

v_2f : the velocity of the smaller bob after the collision

Any suggestion on how to handle the loss in kinetic energy would be fantastic... thank you.

EDIT: Ok thinking about this... I think I might understand the question now.

Initial Kinetic Energy:

[tex]

KE_i = \frac{1}{2}m_1(v_{1i})^2 + \frac{1}{2}m_2(0)^2

[/tex]

[tex]

KE_f = \frac{1}{2}(v_{1f})^2 + \frac{1}{2}m_2(v_{2f})^2

[/tex]

So the loss of kinetic is [tex] KE_f - KE_i [/tex] ...? right? :)

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