# Homework Help: Range Equation

1. Sep 23, 2010

### delfam

1. The problem statement, all variables and given/known data
a 78g basketball is launched at 40.4 degrees at at 14.2m, ball is released at same height as basket. what speed must the player give the ball.

2. Relevant equations
deltax = 2(Vo^2)sin(2theta)

3. The attempt at a solution
14.2 = 2Vo^2 * (.9871360) / 9.8
69.58 = Vo^2(.9871360)
Vo^2 = 70.48
Vo = 8.4

2. Sep 23, 2010

### alphysicist

Hi delfam,

I don't believe this equation is quite right. What should it be?

3. Sep 24, 2010

### delfam

is it just (Vo^2) and not 2(Vo)^2

4. Sep 24, 2010

### jhae2.718

Try solving for the general form of the range equation by taking
$$x(t)=v_0\cos(\theta)t \,\,\,\,(1)$$ and
$$y(t)=y_0+v_0\sin(\theta)t-\frac{gt^2}{2} \,\,\,\,(2)$$
solving (2) for the final time ($$t_f$$), and then substituting $$t_f$$ into (1) and simplifying.

Hint: your expression is missing a term from one of these equations.

Last edited: Sep 24, 2010