Ball's Acceleration: How to Calculate with Initial and Final Time and Height

[mohdakram]

The question is attached.
The correct answer is D

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.

 

[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?

 

[mohdakram]

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

 

[kuruman]

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

 

[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}