[western50]

The racquet ball with a mass of 0.238 kg is moving straight toward the wall at a velocity of vi = 12.8 m/s. The ball makes an inelastic collision with the solid wall and leaves the wall in the opposite direction at vf = -8.1 m/s. The ball exerts the same average force on the ball is 66.108N.

How can I get the change in kinetic energy of the racquet ball?




An object with total mass mtotal = 16 kg is sitting at rest when it explodes into three pieces. One piece with mass m1 = 5 kg moves up and to the left at an angle of θ1 = 25° above the –x axis with a speed of v1 = 26.7 m/s. A second piece with mass m2 = 5.2 kg moves down and to the right an angle of θ2 = 30° to the right of the -y axis at a speed of v2 = 21.6 m/s. m3=5.8 kg, and v3 = 13.212 m/s.

What is the increase in kinetic energy of the pieces during the explosion.
I am confused because there is both x and y component, so how can I deal with it?

[Unknown008]

1. Is that this difficult?

Change in KE = Final KE - Initial KE

Or did you mean momentum?

Or a little harder, but not impossible, the time with which the ball was in contact with the wall?

2. Yes, break all of them into two components, an x and a y component.

The total momentum along the x axis should be 0, and the y coordinate along the y axis should be zero.

[western50]

I got the first question, but for the second question, I add all the kinetic energy of each piece has and divide by 3, am I right? And I will get 1167.165J?

[Unknown008]

Ok, I admit that I didn't read the question but only looked at the picture, and it's a lot easier than I previously thought. (I thought that the velocity and mass of 1 and 2 were given and you were required to find the change in kinetic energy of the last particle.)

It uses the same principle as in the first question.

Change in KE = Final KE - Initial KE

Do that for each of the parts formed by the explosion.

[josephnuroho]

For the increase in KE, you just need to calculate the KE for each piece and add them together.
So, increase in KE = 1/2 m1 * v1^2 + 1/2 m2 * v2^2 + 1/2 m3 * v3^2 =...
I just finished this same question. Gudluck!