00:01
Hi, in this question we have that is a 100 gram ball moving to the right at 4 meters per second collides head on with the 200 gram ball moving to the left.
00:12
This 100 grams, went to right at 4 meters per second.
00:17
Then we have 200 grams, moving to left at 3 meters per second.
00:25
So we're taking right as positive direction and left as a negative direction.
00:29
So this is minus 3.
00:31
The collision is perfectly elastic under the speeds of each ball after collision.
00:36
So because the collision is very elastic, kinetic energy is conserved.
00:42
And so first we can, and also momentum is conserved.
00:45
So for the conservation of momentum, we're going to multiply the velocities and the masses of the objects before collision.
00:54
And equated to the sum of the velocities multiplied with the masses for each ball.
01:01
So we have velocity times mass, 100 grams, times.
01:08
4 meters per second plus 200 grams times minus 3 meters per second is equal to so we need to convert the grams to kilograms so this will be 0 .1 kilograms this would be 0 .2 kilograms so we have 0 .1 here 0 .2 is equal to 0 .1 times the final velocity of this one that's called this v1 and the final velocity of this is called v2 plus 3 .2 v2.
02:03
Next we can get under equation from the coefficient of restitution and if the point of the coefficient the restitution when the collision is elastic the coefficient of restitution will be equal to 1 and formula for that is e is equal to v2 minus v1 by u1 minus u2 this is equal to 1 so we have v2 minus v2 and it by u1 divided by u1 is the inch velocity of the first ball which is four meters per second minus you two which is minus three minus minus three so that's four plus three so we get v2 minus v1 is equal to seven so this is equation one this is equation two so v1 will be called to minus 5 .3 meter per second and v2 will be called to 1 .67 meters per second...