# Homework Help: Path of a cricket ball

1. May 24, 2013

### eejpama

1. The problem statement, all variables and given/known data
model the run up a bowler takes before he throws the cricket ball

2. Relevant equations
model the path of the cricket ball

3. The attempt at a solution
we can make any assumption. if anyone good in physics please helo me model it.

2. May 24, 2013

### CWatters

If this is homework you should have a go yourself first.

PS: He doesn't just "throw" the cricket ball (that would be an illegal delivery) he bowls it with a straight arm. I'm not just being picky. This might help you answer the question.

3. May 24, 2013

### eejpama

i have done some work and equations. but when balls hits the ground i dont understand how to work it out because bounce on ground before it rise again to touch the bat. at that moment i want to know the initial velcity whether it is zero or not? just confused

4. May 25, 2013

### CWatters

No not zero velocity. If it bounces the [STRIKE]velocity[/STRIKE] speed just after the bounce won't be very different to that just before the bounce. Just the direction changes.

You could model the impact with the ground as an elastic collision or an inelastic collision or perhaps just assume the speed doesn't change. Although obviously the direction does (up rather than down).

http://en.wikipedia.org/wiki/Elastic_collision

"An elastic collision is an encounter between two bodies in which the total kinetic energy of the two bodies after the encounter is equal to their total kinetic energy before the encounter" (eg none lost to heat, sound etc)

http://en.wikipedia.org/wiki/Inelastic_collision
"Inelastic collisions may not conserve kinetic energy, but they do obey conservation of momentum"

5. May 25, 2013

### eejpama

thank u that is really helpfull.