Solving for v: "Calculating the Speed of Puck After Collision

In summary, the conversation involves a head-on collision between a 0.440kg ice puck moving east at 3.16m/s and a 0.940kg puck initially at rest. The lighter puck's speed is calculated using two equations and substitution, but there may be two possible solutions that need to be distinguished by labeling the pucks as m1 and m2.
  • #1
BadSkittles
34
0
A 0.440kg ice puck, moving east with a speed of 3.16m/s, has a head-on collision with a 0.940kg puck initially at rest. Assuming a perfectly elastic collision, what is the speed of the lighter puck? Use east as the positive axis.

I got -2.09.

I made two equations and used substitution to find the speed of the lighter puck. But its wrong. Would appreciate all help.


initial final
1/2mv^2= 1/2 mv^2 + 1/2 mv^2

m(v) = m(v) + m(v)
 
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  • #2
How about distinguishing symbolically between the lighter and the heavier puck? Like, call the lighter m1 and the heavier m2, and same for the velocities.

Rewrite your equations that way and try again. You seem to have the right basic idea.

Hint: there are two solutions to (v1,v2). The second set is physically impossible even though not violating either momentum or energy conservation.
 

Related to Solving for v: "Calculating the Speed of Puck After Collision

1. How do I calculate the speed of a puck after a collision?

To calculate the speed of a puck after a collision, you will need to know the mass of the puck, the initial velocity of the puck, and the mass and velocity of the other object involved in the collision. You can use the equation v = (m1v1 + m2v2) / (m1 + m2), where m1 and v1 are the mass and velocity of the puck, and m2 and v2 are the mass and velocity of the other object.

2. What units should I use for the mass and velocity in the calculation?

The units for mass should be the same for both the puck and the other object, such as kilograms. The units for velocity should also be the same, such as meters per second. It is important to use consistent units to ensure accurate calculations.

3. Can I use this equation for collisions between more than two objects?

No, this equation is specific to calculating the speed of a puck after a collision with one other object. For collisions involving more than two objects, you will need to use different equations and take into account the velocities and masses of all objects involved.

4. What other factors might affect the speed of the puck after a collision?

In addition to the mass and velocity of the objects involved, other factors that may affect the speed of the puck after a collision include the coefficient of restitution (a measure of how much energy is lost during the collision), the angle of collision, and any external forces acting on the objects.

5. How do I know if my calculation is accurate?

To ensure accuracy, it is important to double-check your calculations and use appropriate units. You can also compare your calculated speed to the actual speed of the puck after the collision, which can be measured using tools such as a speed sensor or high-speed camera. If there is a significant difference between the calculated and actual speed, you may need to review your calculations or consider other factors that may have affected the collision.

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