Help on homework?

Question

Acceleration = final velocity – initial velocity / elapsed time between two measurements

So: 91.5 – 0 / ????

What times do I subtract?

Data table for ball rolling down 10 degree incline lab:
Distance Time
91.50 1.16
76.25 1.12
61.00 .99
45.75 .83
30.50 .72
15.25 .53

I know velocity is d/t. Which numbers do I plug in where, to find acceleration? I tried and the numbers I got don’t match the scale for the graph at all. *See previous questions for more.
I don't know what to plug in where.
The lab was an inclined plane at 10 degrees with six sections marked off. We rolled the ball from each section until the end, timing it (from 15.25 cm, to the end, 0). Help...

Answer 1

The velocity is not constant and will vary from start to finish. Take each distance measurement, subract it from the previous distance measurement; do the same for the corresponding time values. For example, where the distance is 45.75, the time is .83. The previous distance is 30.50 (and its corresponding time is .72). Subtract the distances 45.75-30.50 to get 15.45; subtract the times .83-.72 to get .11; divide the distance difference by the time difference to get the velocity at those points. Do this for all points. You can plot these on a graph of velocity vs time; it should be a straight line. The slope of that line is the acceleration. You can also get the acceleration by subracting the velocities and times the same way you did for distances and times; the numbers should all come out roughly the same. Average them all to get a good measurement of acceleration.

Answer 2

So first find the final and initial velocity.

Initial velocity: 91.5/1.16 = A
Final velocity: 15.23/.53 = B

Then find the elapsed time: 1.16 - 0.53. = C

So, acceleration = (B - A) / C

Answer 3

You have to figure out velocity first.

V = (d2 - d1)/t = (91.5 - 15.25)/(1.16 - 0.53)

Now use the velocity to calculate acceleration.

A = V/t = V/(1.16 - 0.53) = ?

Answer 4

jsut plug it into excel and do a curve fit and then take the derivtive twice...
with your numbers i got around 1.4 m/s^2


the value for a should be around 1.7 m/s^2, not terribly far off