# Working out the initial velocity

1. Apr 4, 2014

### theholychilli

1. The problem statement, all variables and given/known data
Tom decided to attempt to jump a 200m wide river on rocket skates. He built a 60m long ramp with an angle of 30° to the horizontal and plans to land on a mattress at ground level. Determine the launch speed necessary for Tom to be successful.

2. Relevant equations

vo = √Rg/Sin(2 * θ)

3. The attempt at a solution

vo = √200 * g/Sin(2 * 30)
vo = √200*g/0.866

Not a homework question, but I stumbled upon this and want to learn this stuff.

2. Apr 4, 2014

### Staff: Mentor

Hi theholychilli. http://img96.imageshack.us/img96/5725/red5e5etimes5e5e45e5e25.gif [Broken]

I very much doubt that there is a neat formula going around which you can memorize for this problem. Much better that you learn to figure it out for yourself.

The first step is to draw a large clear diagram, and mark on all the relevant details you know. See how you go with that.

I think there is an assumption that is going to have to be made about the skates, too ....

Last edited by a moderator: May 6, 2017