# Trying to find height

1. Jun 8, 2009

On a hot summer day, a young girl swings on a rope above the local swimming hole . When she lets go of the rope her initial velocity is 2.05 m/s at an angle of 35.0 degrees above the horizontal.
If she is in flight for 0.614 , how high above the water was she when she let go of the rope?

so I think it forms a right triangle and from there I just use the pythagorean theorem and then the Y is my height?

I just have no idea

2. Jun 8, 2009

### Cyosis

This is a resistanceless projectile problem, that means her trajectory will be a parabola. You will have to use kinematic equations. What's the kinematic equation for the y-direction motion? What acceleration is she subjected to in the y-direction?

3. Jun 8, 2009

4. Jun 8, 2009

### Cyosis

I am indeed. You want to find $y_0$ in that equation.

5. Jun 8, 2009

I think acceleration is 9.81

6. Jun 8, 2009

### Cyosis

Almost, don't forget gravity is pulling her down while she is flying up so it's -9.81. You can also calculate v_y and you know t.

7. Jun 8, 2009

Isn't y=0 and Vyo 2.05 m/s ?

8. Jun 8, 2009

### Cyosis

She stops being in flight when she hits the surface of the water, which is where we have set our 0 point, so indeed y=0. However vy0 is not 2.05 m/s v=2.05 m/s, which is a vector that makes an angle of 35 degrees with the horizontal. You want to know the y-component of this vector.

9. Jun 8, 2009