# Find the Time and write it as a power

1. Jul 7, 2009

### waxer1987

1. The problem statement, all variables and given/known data
Acceleration: -0.20m/s^2[E] Initial Velocity: 24m/s[E] Final Velocity 12m/s Time(s): ?
I need to find the Time and write it as a power. The answer is 6.0 x 10^1s. I don't understand how they got this or how to write it as a power.

2. Relevant equations

3. The attempt at a solution
-0.20m/s^2 = 24m/s[E] - 12m/s[E] / Time
Time = 24m/s - 12m/s + 0.20m/s^2

2. Jul 7, 2009

### rl.bhat

Re: Kinematics

Time = 24m/s - 12m/s + 0.20m/s^2This step is wrong.
It should be (24m/s - 12m/s) / 0.20m/s^2.
writing in power means write 125 as 1.25x10^2

3. Jul 7, 2009

### dotman

Re: Kinematics

Well, this is really two problems-- one the physics problem of finding the time given the initial velocity, final velocity, and acceleration, and the second being how to write a given value as a power of 10.

It looks like you tried to apply the formula

(Vfinal - Vinitial) / t = a, but you made an algebraic error-- you added the acceleration to both sides, instead of dividing by it!

Once you get the answer, you can write it as a power of 10. There may be some formal way of doing this, but for some value, you can just look at how many decimal places you need to move the decimal point to get a single digit, and thats your power of ten. Each decimal place is a power of ten. For example, say your value is 1023. You need to move the decimal point three spots to the left, so it would be written:

1023 = 1.023 x 10^3

Hope this helps!