# Conservation of energy and height of projectile

1. Oct 11, 2006

### numb401

A child slides without friction from a height h along a curved water slide (Fig. P5.44). She is launched from a height h/5 into the pool. Determine her maximum airborne height y in terms of h and . (Use q for and h as appropriate.)

I understand that you use conservation of energy to solve the problem, but for some reason my brain is dead to physics today. O-chem/Calc 1/Bio I can handle but for some reason these word problems are really tripping me up.

Here's what I have so far.

W(nc) =(KEf + PEf) - (KEi + PEi)
0 = 1/2mv^2 + mg(h/5) - (0 + mgh) (For the end of the slide to find velocity when she leaves slide)
ymax = vo^2sin^2(q) /(2 g)

Am I on the right track?

2. Oct 11, 2006

### edavey8205

yes it is looking good, except i think you have some typo's in the last equation line, but i know what you mean.

3. Oct 11, 2006

### numb401

I ended up with ymax = (-h/5 + h)*(sin(q))^2 and its registering as incorrect. Notice any errors?

4. Oct 11, 2006

### edavey8205

how did you get (-h/5 + h)? I'm not getting that from using the energy equation solving for v.

5. Jan 8, 2009

### Sammy Twit

u've got it wrong- it's conservative since it's frictionless