How to find acceleration from distance and time?

[SagarPatil]

Homework Statement

The problem is asking to find acceleration from distance and time measurements. It is also asking to find acceleration from Newtons second law

This was a linear air track lab if you're wondering.

Whats given:
Distance = 81 cm
Total mass moved = 200g
Weight Force = 1.471N (150g)
Time = 0.003 secs (This might be wrong, but forget it. I just want to know how to calculate acceleration)

Homework Equations

S=ut+0.5*a*t^2

Where
S = distance
u= Initial velocity
a= accleration
t=time

The Attempt at a Solution

So,

0.81m = (0)(0.003)+(0.5)(0.003)^2(a)
0.81m=4.5x10^-6a
a= 1.8x10^-7 m/s^2

I am using the formulas from this website
http://www.mathalino.com/reviewer/engineering-mechanics/motion-particle

 

[SagarPatil]

Here is my second attempt

where v = final velocity

v+u=2s/t
v=2s-u/t
v=2(0.81)-0/0.003
v=540 m/s^2

v-u/t
540-0/0.003

a= 18,000 m/s^2

 

[haruspex]

You seem to be having some trouble with the arithmetic.

0.81m=4.5x10^-6a
a= 1.8x10^-7 m/s^2

All was fine until the last step. try that again.

v=540 m/s^2

You mean m/s.

540-0/0.003
a= 18,000 m/s^2

You mean (540-0)/0.003.
Again, you made an arithmetic mistake at the last step.

 

[SagarPatil]

Yea thanks I got 180,000 m/s on both

On the first one 0.81/4.5x10^-6
=180,000 m/s

second one

540-0/0.003
=180,000 m/s

So the steps I did are correct?

 

[haruspex]

Yea thanks I got 180,000 m/s on both

On the first one 0.81/4.5x10^-6
=180,000 m/s

second one

540-0/0.003
=180,000 m/s

So the steps I did are correct?

Yes.