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Homework Help: Relationship Between Acceleration on a ramp and Acceleration due to gravity

  1. Oct 28, 2014 #1
    1. The problem statement, all variables and given/known data
    We performed a lab to find an experimental value of gravity. I used a ramp with a height of 0.08 m, and the ramp was 1 m long. The ramp made an angel of approximately 4.59 degrees with the horizontal. We used software to calculate velocity with respect to time and position with respect to time graphs. Using the formula for our position over time graph which was displayed on the graph as Ax^2+Bx+C, with an A value of 0.2236, which I have assumed for units to ad up is our acceleration value. Now, we need to use some kind of formula to find the relationship between a_ramp and g.

    2. Relevant equations

    3. The attempt at a solution
    I thought that ma=mg would make a=g/(sin(angle)) but this is incorrect...
    Our TA put up something on the board that looked like this:
    where # is supposedly the fraction of kinetic energy caused by linear instead of rotational motion,
    but I have no idea why that is true. I even did the whole energy conservation equation, keeping in mind that vi =0, but I cannot derive any sort of equation to show that this whole a=g# thing is true. Any advice would be helpful; I feel I'm missing some key concept here and my TA refused to talk to me further to allow me to understand.
  2. jcsd
  3. Oct 28, 2014 #2

    Doc Al

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    Staff: Mentor

  4. Oct 28, 2014 #3
    Hi, could you explain why the formula appears to be F=mgsin(angle)? I don't understand from the reading why the sin(angle) is on that side of the equation... Is that just a formula that I should know or is my trigonometry wrong?
  5. Oct 28, 2014 #4


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    Staff: Mentor

    Hi SS. http://img96.imageshack.us/img96/5725/red5e5etimes5e5e45e5e25.gif [Broken]

    Show the diagram you drew that led you to this equation.

    If the slope was very gentle, this equation of yours would produce huge accelerations along the slope.
    Last edited by a moderator: May 7, 2017
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