# Homework Help: Physics-Motion and Gravity Help!

1. Jul 2, 2008

### lilaSA

Physics--Motion and Gravity... Help!

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

I have this really great excercise book that gives you excercises with no explanation how to do it. The question is: For a baseball to travel 90m, with what velocity must it be hit if the angle of impact is 40º? The flight time is 3.9 sec. I have absolutely no idea how to start solving this!

2. Relevant equations

3. The attempt at a solution

2. Jul 2, 2008

### Hootenanny

Staff Emeritus
Re: Physics--Motion and Gravity... Help!

Welcome to PF lilaSA,

You must have some idea as to where to start, which concepts are involved?

3. Jul 2, 2008

### lilaSA

Re: Physics--Motion and Gravity... Help!

What do you mean concepts? The majority of the excercises require you to solve problems in connection with the height or speed of objects, but normally they give the velocity at which it travels. I'm quite confused

4. Jul 2, 2008

### Kurdt

Staff Emeritus
Re: Physics--Motion and Gravity... Help!

What equations do you normally use to solve those problems? They can be used to solve this one, except this time you will be finding the initial velocity.

5. Jul 2, 2008

### lilaSA

Re: Physics--Motion and Gravity... Help!

The equations they use to solve velocity is normally change in distance/change in time... I've tried that, but the answer is still incorrect. I have also tried solving it by using the gravity measurement thingy and working it into the equations, but that didn't work either. My physics teacher moved, now I'm stuck lol

6. Jul 2, 2008

### lilaSA

Re: Physics--Motion and Gravity... Help!

There is another equation I just found, it is: velocity = gravity x time... Does that help?

7. Jul 2, 2008

### Kurdt

Staff Emeritus
8. Jul 2, 2008

### lilaSA

Re: Physics--Motion and Gravity... Help!

OK thanks... I've gone to the link, but I still need to solve the problem using the degrees? I'm sorry, I'm quite clueless with these things

9. Jul 2, 2008

### lilaSA

Re: Physics--Motion and Gravity... Help!

I think I get it now, thanks so much!