This discussion centers on solving an AP Physics problem involving a collision between a 5-kilogram ball and a 0.5-kilogram cube. The cube, moving at 26 meters per second, strikes the ball, which then leaves the table. The participants determined the horizontal velocity of the ball after the collision to be 4.727 m/s to the right and the cube's speed to be 21.27 m/s to the left. The collision is confirmed to be inelastic, as kinetic energy is not conserved, despite momentum being conserved.
PREREQUISITESAP Physics students, educators teaching mechanics, and anyone interested in understanding collision dynamics and momentum conservation.
physicsgirl101 said:Part d of the problem says: Determine the kinetic energy dissipated in the collision.
I know kinetic energy was lost, because it was an inelastic collision, but when I do it out I get that no kinetic energy is lost:
before collision:
(1/2)(.5)(26^2)+(1/2)(5)(0) = 169
after collision:
(1/2)(.5)(21.27^2) + (1/2)(5)(4.727^2) = approx. 169
I'm assuming I got this incorrect result because the velocities I used (21.27 and 4.727) are incorrect---because the collision would have to be elastic for them to be correct, and thus it makes sense that in an elastic collision the energy would be conserved... So basically this goes back to my last post----I need to find the correct v1 and v2... Can anybody help? Please!
physicsgirl101 said:Alright... After a lot of work, this is what I got:
immediately after the collision:
speed of ball: 2.4m/s
speed of cube: 2m/s (going to the right---the same direction as the ball*)
I then gathered that 153.6 Joules of kinetic energy was lost in the collision...
How does that all sound? (especially the direction of the ball??)