# Derive from projectile motion equation

1. Aug 5, 2014

### chinstixx

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

Derive:
R=v^2sin2theta/g

Show that R=V0^2/g

2. Relevant equations

3. The attempt at a solution

This is my first time to take up physics so I have no idea at all on how to do this, to be honest.

2. Aug 6, 2014

### Simon Bridge

Start with a sketch of the motion, then draw the velocity-time graphs for the horizontal and vertical components.
The area under the horizontal graph is the range R.

This would be a very unusual problem for a first-time physics student.
Normally you would learn things like the definitions for velocity and displacement and drawing graphs and Newton's laws before you get to ballistics.

3. Aug 6, 2014

### chinstixx

Thank you. There was no graph provided for this. Can this still be solved?

4. Aug 6, 2014

### chinstixx

Also, I have no sufficient knowledge of trigonometry to be able to derive equations like this.

5. Aug 6, 2014

### Simon Bridge

You have to make the graph yourself - it can also be done from the kinematic equations.
You do need trigonometry to divide the initial velocity into horizontal and vertical components.
You also need to know how to find the slope of a line and how to find the areas of a triangle and a rectangle.
If you do not have these skills, or the ability to sketch v-t graphs, then you need to acquire these skills before attempting problems like this one.