Find the final velocity of the two pucks after the collision

In summary, two hockey pucks with initial speeds of 21 m/s and 14 m/s collide and stick together. Since the masses are not given, it is assumed that they are either equal or a multiple of each other, resulting in the cancellation of the m terms in the equations. However, more information is needed to determine the exact outcome of the collision as it is an inelastic collision.
  • #1
dorian_stokes
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Homework Statement


Two hockey pucks approach each other as shown in the figure below. Puck 1 has an initial speed of 21 m/s, and puck 2 has an initial speed of 14 m/s. They collide and stick together.


Homework Equations





The Attempt at a Solution

The pucks didn't have a mass so I couldn't use the components.
 
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  • #2
Almost always in a collision problem like this, when the mass is not given that means the m terms will cancel out. Either the two pucks are of equal mass and the m's easily cancel or the mass is different, but is a multiple of the other mass. For example, one mass might be m and the other 3m, but the m's still cancel. I don't know whether or not the masses are the same, but if it is not specified, I would assume they are of equal mass.
 
  • #3
You'll need to provide more information. This is an inelastic collision so the masses canceling out is unlikely except in only certain situations.
 

1. What is the formula for finding the final velocity of the two pucks after a collision?

The formula for finding the final velocity of the two pucks after a collision is given by: Vf = (m1 * V1 + m2 * V2) / (m1 + m2), where Vf is the final velocity, m1 and m2 are the masses of the two pucks, and V1 and V2 are their initial velocities.

2. Is there a difference in the final velocity if the collision is elastic or inelastic?

Yes, there is a difference in the final velocity depending on the type of collision. In an elastic collision, where kinetic energy is conserved, the final velocity of both pucks will be different from their initial velocities. In an inelastic collision, where some kinetic energy is lost, the final velocity of both pucks will be the same.

3. What is the importance of conservation of momentum in finding the final velocity of the two pucks?

Conservation of momentum is important in finding the final velocity of the two pucks because it states that the total momentum of a system before and after a collision remains constant. This allows us to use the formula Vf = (m1 * V1 + m2 * V2) / (m1 + m2) to calculate the final velocity.

4. How do you determine the initial and final velocities of each puck in a collision?

The initial velocities of the pucks can be measured or given in the problem. The final velocities can be calculated using the formula Vf = (m1 * V1 + m2 * V2) / (m1 + m2). It is important to note that the velocities must be in the same direction for the formula to be accurate.

5. Can the final velocity of the two pucks be greater than the initial velocities?

Yes, in some cases, the final velocity of the two pucks can be greater than their initial velocities. This can happen in an elastic collision where the kinetic energy is conserved and the pucks have different masses. In an inelastic collision, the final velocity of both pucks will always be less than or equal to their initial velocities.

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