Posted by **Jeremy** on Thursday, March 7, 2013 at 1:44am.

I'd like to know when it is appropriate to use each formula. Im new to studying physics and its seems that there are certain situations when one formula leads to the answer, yet a derivative of that formula that should lead to the answer is incorrect.

For example: the question was if i toss a ball in the air, and the Distance =0 (as a ball comes back to the ground and tossed from the ground), Time= 2 seconds, and acceleration = -10m/s^2. What is the initial velocity?

I tried using the Change in Velocity= Acceleration x Time. which should work because i am given acceleration and time. My working out is:

Vfin-Vini = -10m/s^2 x 2seconds

vfin=0 - Vini= -20

vini= 20m/s

But apparently the correct way to answer this question is to use this formula : Change in D= Vinitial x time + acceleration x Time ^2/2. Which works out to be 10m/s

If anyone could please tell me when it is appropriate to use each formula. OR where i have gone wrong in this please let me know

## Answer this Question

## Related Questions

- Physics - The question said find the speed of sound at a certain temperature. ...
- Physics - On the question that someone posted.....I asked my teacher on what ...
- Physics - Whats the difference between frictionless and friction in a way of ...
- physics - i'm not very good at physics and i have an exam tomorrow!! for the ...
- Check my physics - Would you mind checking one of my problems from my physics ...
- Physics - I'm having trouble understanding which formula to use to answer this ...
- COLLEGE MATH - What percentage of 40 IS 120? I used the formula: 40 =x*120 -40 -...
- physics help!!! - How do you find the speed of sound wave using the formula for ...
- Physics E=mc^2 - Can you explain what formula (like quadrantic..whatever formula...
- Chemistry - In a experiment to determine the molecular weight and the Ka for ...

More Related Questions