# Physics/Calculus Problem, help needed

1. Aug 11, 2011

### Charles De Ga

1. The problem statement, all variables and given/known data

Can someone help me to prove that scientifically my theory:

The ball goes faster from point A to B if it doesn't touch the ground. That is to say, a pass at chess level is faster then a pass that rebounded one. (Always from point A to B with the same force applied)

2. Relevant equations

Which on is faster?

3. The attempt at a solution

I think that my theory is right.
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. Aug 11, 2011

### HallsofIvy

Staff Emeritus
Well, why do you think that? That's the crucial point, isn't it?

3. Aug 11, 2011

### doppelganger

What is the total length of the path the ball takes on its way from point A to point B? Is it the same length for a chest level pass and a rebound pass? If the lengths are are different and the speed of the ball the same, then one will travel from point a to point b in less time than the other.

4. Aug 11, 2011

### Charles De Ga

The chest level pass goes from the chest level of a player to the chest level of another.

Yes, the paths are different (One ball hits the ground and the other one doesn't) but the distance are the same: From one player to another. The path for the chess level pass is shorter and the path for the rebound pass longer.

The values were not specified.

So which one will be faster?

Again, thanks for your precious help.

5. Aug 11, 2011

### Staff: Mentor

What is the context of the question? Is this for schoolwork, or for your basketball team?

6. Aug 11, 2011

### Redbelly98

Staff Emeritus
Well, that and some common sense should provide the answer. As was said:
("length" is referring to the to the path the ball travels)

7. Aug 11, 2011

### Clever-Name

I guarantee the path travelled by the ball during the bounce pass will be longer than the path travelled by the ball during a chest-chest pass. Draw a simple picture and define an arbitrary lenght. Do the math.

8. Aug 11, 2011

### Charles De Ga

Thanks everybody.

9. Aug 11, 2011

### Charles De Ga

I got confused and I thought that though the rebound pass had a longer path, it would be faster since the ball was accelerated by gravity.

10. Aug 12, 2011

### Ray Vickson

If you compare tossing the ball at speed s at an angle A up from the horizontal, vs. tossing it at speed s at the same angle A down from the horizontal, the first will be "chest-level" and the second a "rebound". In the absence of friction (air and bounce friction) both would arrive at the same time, because the horizontal speeds are the same. Gravity acts vertically, so does not affect how long it takes the ball to go a certain horizontal distance (again, this in the absence of friction and inelastic bounce of the ball).

RGV

11. Aug 12, 2011

### HallsofIvy

Staff Emeritus
Yes, neglecting friction, the horizontal speed of the ball is the same and the time of the two passes would be identical.

On the other hand, air resistance and friction when the ball hits the ground would be important and would make one pass take longer than the other. Which takes longer?

12. Aug 12, 2011

### Redbelly98

Staff Emeritus
However, the problem statement (as posted here) did not specify the angles that the two passes are thrown at.

I think we all reasonably assumed the speed was the same for both. Additionally, I was assuming that the chest-level pass was thrown closer to horizontally than was the bounce pass. Maybe my assumption was wrong.