# Kinematics - How long does this basketball take to fall down

1. Sep 26, 2007

### maryyy16

I have no idea how to even begin this problem:

At the beginning of a basketball game, a referee tosses the ball straight up with the speed of 4.6 m/s. A player cannot touch the ball until after it reaches its maximum height and begins to fall down. What is the minimum time that a player must wait before touching the ball?

2. Sep 26, 2007

### Avodyne

First, take an inventory of what you know. Initial position? Well, we can just agree to call the initial height zero. Initial velocity? Yes: 4.6 m/s, with the upward direction being positive. Acceleration? Yes, it's the acceleration of gravity, a = -9.8 m/s2. (Do you know why there's a minus sign?)

Now, what about position, velocity, acceleration, or time characterizes the basketball when it's at its maximum height?

3. Sep 26, 2007

### mgb_phys

As the ball is thrown up it slows down at a rate of 'g' = 9.8m/s^2
At the top of the curve it has a speed of 0.
What is the relationship between speed, acclearation and time ?

4. Sep 27, 2007

### darkness_limits

u have the formula: x=0.5*a*(t^2)+v(0) where x is the maximum heigh and a is 9.8 and t is the time and v is the initial speed. just calculate it