Physics - elastic collision

In summary, Two blocks, one with a mass of 5.00kg and the other with a mass of 10.0kg, slide along a frictionless wooden track. The first block is released from point A, with a north pole magnet protruding from its front end, repelling an identical magnet embedded in the back end of the second block, which is initially at rest. Using conservation of kinetic energy and momentum, the final velocity of the first block after the collision can be calculated. This energy can then be converted into gravitational potential energy to determine the maximum height to which the first block rises. Two equations, "total momentum before = total momentum after" and "total KE before = total KE after", are used to solve
  • #1
physixnot4me
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(3) two blocks are free to slide along the frictionless wooden track. a block of mass m1=5.00kg is released from A. Protruding from its front end is the north pole of a strong magnet, repelling the north pole of an identical magnet embedded in the back end of the block of mass m2=10.0kg, initially at rest. the two blocks never touch. Calculate the maximum height to which m1 rises after the elastic collision.

Do you use conservation of kinetic energy and momentum to figure out the final velocity of the block M1 after the collision. Then let all that kinetic energy be converted to gravitational potential energy to determine how high it rises?

what equations are appplied to a question like this?
 

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  • #2
physixnot4me said:
Do you use conservation of kinetic energy and momentum to figure out the final velocity of the block M1 after the collision. Then let all that kinetic energy be converted to gravitational potential energy to determine how high it rises?
what equations are appplied to a question like this?
Yes. Since you have two unknowns (v1 and v2, both "after" the collision) you need two equations. The equations you use are the "total momentum before = total momentum after" and the "total KE before = total KE after" equations:
 
  • #3


In order to calculate the maximum height to which m1 rises after the elastic collision, we can use the equations of conservation of kinetic energy and momentum.

First, we can calculate the final velocity of the block m1 after the collision using the equation:

m1v1i + m2v2i = m1v1f + m2v2f

Where m1 and m2 are the masses of the two blocks, v1i and v2i are the initial velocities of the blocks, and v1f and v2f are the final velocities.

Since the two blocks are initially at rest, v1i = 0 and v2i = 0. Also, since the collision is elastic, kinetic energy is conserved, so we can use the equation:

1/2 m1v1i^2 + 1/2 m2v2i^2 = 1/2 m1v1f^2 + 1/2 m2v2f^2

Solving for v1f, we get:

v1f = (m1 - m2) / (m1 + m2) * v1i

Next, we can use the equation for conservation of momentum to calculate the final velocity of m2:

m1v1i + m2v2i = m1v1f + m2v2f

Solving for v2f, we get:

v2f = 2m1 / (m1 + m2) * v1i

Now, we can use the equation for gravitational potential energy to calculate the maximum height h to which m1 rises:

m1gh = 1/2 m1v1f^2

Solving for h, we get:

h = v1f^2 / (2g)

Substituting the values for v1f and g, we get:

h = [(m1 - m2) / (m1 + m2) * v1i]^2 / (2g)

Therefore, we can use these equations to calculate the maximum height to which m1 rises after the elastic collision. It is important to note that these equations assume a frictionless wooden track and no external forces acting on the system, so they may not be accurate in real-world scenarios. However, they provide a good estimate for theoretical calculations.
 

1. What is an elastic collision?

An elastic collision is a type of collision between two objects in which there is no loss of kinetic energy. This means that the total kinetic energy before the collision is equal to the total kinetic energy after the collision.

2. How is momentum conserved in an elastic collision?

In an elastic collision, momentum is conserved because the total momentum of the two objects before the collision is equal to the total momentum after the collision. This means that the total mass times velocity of the two objects before the collision is equal to the total mass times velocity after the collision.

3. What is the difference between an elastic collision and an inelastic collision?

In an elastic collision, there is no loss of kinetic energy and the objects bounce off each other. In an inelastic collision, there is a loss of kinetic energy and the objects may stick together or deform upon impact.

4. How do you calculate the final velocities in an elastic collision?

The final velocities in an elastic collision can be calculated using the conservation of momentum and the conservation of kinetic energy equations. These equations take into account the masses and initial velocities of the objects as well as the angles at which they collide.

5. Can an elastic collision occur between objects of different masses?

Yes, an elastic collision can occur between objects of different masses. As long as the objects have the same velocity and no energy is lost during the collision, the collision can be considered elastic. However, the final velocities of the objects will be different due to the difference in their masses.

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