Science Buddies: "Ask an Expert"

ball moving down an inclined plane. Which equations i should use ?I have the mass of the ball, time and distance which it travels off the inclined plane. I did the real life experiment but i don't know how to calculate the ball's velocity and acceleration to prove my hypothesis that the heavier the ball was, the slower it accelerated. Please help me.Thanks alot

Hi!
Awesome, that's great that you have results! So now for the calculations- here's a link I thought would be helpful that tells you how to solve similar inclined plane problems. Following their general guidelines, you can apply it to your own specific problem and support your hypothesis!
http://www.sparknotes.com/testprep/book ... ion3.rhtml
Hope this helps, good luck!

Hi duyenphamdp,

It's good that you measured the distance each ball traveled and the time it took to travel that distance, because that's exactly what you need to calculate the acceleration. You also need the initial velocity of the balls, but that should be zero if you released them from rest without pushing at the top of the ramp. In this case, the equation that you need boils down to [distance] = 0.5 [acceleration] * [time}^2. You can read about the constant-acceleration equations of motion in most physics or calculus textbooks, but here are some online resources:

http://www.ac.wwu.edu/~vawter/PhysicsNe ... otion.html
http://id.mind.net/~zona/mstm/physics/m ... Motion.htm

Note that while this gives you a way to calculate the acceleration from your data, it doesn't actually treat the forces involved. Gravity causes an object on an inclined plane to accelerate -- see staryl13's link for an example of this. However, your situation is a little bit different because balls roll instead of sliding. Some good terms to look up would be moment of inertia, torque, and angular acceleration. The force that works against gravity in this case is called rolling friction or rolling resistance.

Amanda