# Question on Ball Launching

1. Jul 2, 2012

### czieg98629

I have a 3 inch ball. I want to build a manual ball launcher. I need to get the ball to roll 22 feet. At a 45 degree angle how high would the "launcher" have from the ground?

Thank You

2. Jul 2, 2012

### tiny-tim

welcome to pf!

hi czieg98629! welcome to pf!

(is 45° the slope of the ground, or the slope of the launcher? )

show us what equations you've tried, and where you're stuck, and then we'll know how to help!

3. Jul 2, 2012

### czieg98629

45 degrees is the ball launcher.

I am a sales person --don't have an math formula-- so i was looking for how many inches the ball launcher would need to be in this forum

4. Jul 2, 2012

### Staff: Mentor

Welcome to the PF.

What is the context of the question? Is it for your sales job somehow?

Surely you can appreciate that the answer will depend on the type of ball and type of surface it is landing on. You don't need to launch a steel ball very far to get it to roll 22 feet on concrete. But it it is landing on grass and rolling...

5. Jul 2, 2012

### czieg98629

It is a wood ball on a wood surface.

6. Jul 2, 2012

### tiny-tim

hmm … you've asked how high the launcher needs to be

i originally assumed you meant a spring-operated launcher, in which case the important measurement would be the strength of the spring

but do you instead mean a "ski-jump" launcher, where you let the ball run down a 45° slope which ends above the ground?

7. Jul 2, 2012

### CWatters

The problem isn't well described but lets say...

You have a 45 degree ramp which the ball has to roll down.
Then when it gets to the bottom the ball has to roll 22 feet along the ground.
How high does the ramp have to be?

If thats the problem we can't answer the question. You would need to know how much friction there was between the ground and the ball. The simplest way to work that out would be to build one and try it.

8. Jul 2, 2012

### czieg98629

The launcher is a piece of wood at a 45 degree angle. The front part touches the ground. The question is how high the back part of the wood would have to be for the ball to to 22 feet.

9. Jul 2, 2012

### tiny-tim

czieg98629, this isn't exactly rocket engineering!

it's just a cheap plank of wood, which you can easily place at 45° by simply leaning it against a wall

so try it!!

10. Jul 2, 2012

### CWatters

It's not possible to answer this question for the reason I gave before.

If the floor was made of ice or glass the ball would roll further than if it was made of mud or carpet.

11. Jul 2, 2012

### Chronos

It depends not just on rolling resistance, but also ball diameter and weight. The rolling resistance of wood on wood is roughly .0015

12. Jul 3, 2012

### haruspex

If the slope changes abruptly from 45 degrees to horizontal there will be some loss due to the impact. Better would be a more gradual change. The radius of curvature of this should be greater than that of the ball.