# Homework Help: Find acceleration of a ball

1. Mar 16, 2010

### mohdakram

The question is attached.

I got it as C first using the equation s=ut+1/2 a t^2
I took s as h, and t= (t2-t1)

I put u=0, which I discovered isn't correct. I then tried putting u=at1 and got a complex equation and got stuck there.

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2. Mar 16, 2010

### kuruman

You need to understand that the equation

s = ut + (1/2)at2

gives the position of the object at any time t. In other words, you give me the time and I will use the equation to find the position of the object. So

1. At time t1 the object is at s1 = ut1 + (1/2)at12

2. At time t2 the object is at s2 = ut2 + (1/2)at22

What is u? How is h related to s1 and s2?

Last edited: Mar 16, 2010
3. Mar 17, 2010

### mohdakram

I'm sorry, I still don't get it. How do you solve this question?

4. Mar 17, 2010

### kuruman

What part exactly of my previous posting don't you get?

5. Mar 17, 2010

### mohdakram

I finally found it. I used this equation

s=h
u=at1
v=at2
t=(t2-t1)

$$\frac{s}{t}$$=$$\frac{u+v}{2}$$