1. Jan 18, 2010

### majormuss

1. The problem statement, all variables and given/known data

A basketball player jumped straight up to grab a
rebound. If she was in the air for 0.80 second,
how high did she jump?
(1) 0.50 m (3) 1.2 m
(2) 0.78 m (4) 3.1 m

2. Relevant equations

d=Vit + 1/2at^2

3. The attempt at a solution
my calculations lead to '4' as my final answer, but the book tells me otherwise. There must be something I am missing. need help.

2. Jan 18, 2010

### rock.freak667

Re: Kinemtics

The player is initially at rest and is only subjected to the acceleration of gravity.

3. Jan 18, 2010

### majormuss

Re: Kinemtics

Exactly!, thats i also assumed and if u work it out with that formula the answer turns out 3.1 m/s... but the book says my answer should be 1.2m/s.... doesn't make any sense to me at all.

4. Jan 18, 2010

### rock.freak667

Re: Kinemtics

Well actually '2' seems to work out more, I don't know how your book for 1.2m.

At the highest point, t=0.4s.

5. Jan 18, 2010

### Yitzach

Re: Kinemtics

The problem is that the player's initial velocity is not zero, but unknown. I need to be on my way or I give the eq. you need.

6. Jan 18, 2010

### tiny-tim

Hi majormuss!

She reached the top after 0.40 seconds, so the question is the same as 'how far does something fall in 0.40 seconds?'

7. Jan 18, 2010

### majormuss

Re: Kinemtics