Science Buddies: "Ask an Expert"

hello i have a question regarding the project: Distance and Speed of Rolling Objects Measured from Video Recordings.

i did a variation of this project except i did not record it on a video camera. i used a 1m long board and used marbles of different masses. I have timed each of them and did 10 trials each marble. i have calculated the average time for each marble. my question is how do i find average velocity and acceleration? my teacher refuses to help me.

Hi emm5678-

It's a little hard to believe that your teacher refused to help you. If they suggested that you figure out the solution based on what you learned in class and resources that you can find, that would make more sense. In any case, it can be confusing and comes up here as a question from time to time.

You might want to look at a previous discussion of this: https://www.sciencebuddies.org/science- ... php?t=5571 . This is another site that seems to explain the relationships between time, distance, velocity and acceleration rather well: http://www.physicsclassroom.com/class/1 ... -Equations

Good luck with your project! We're happy to help here so write back if you have more questions. We can't do the work for you though but I think you'll have no problem when you see the equations.

Howard

Hello again,


so i measured the speed of the different marbles in intervals of 12 using the meter stick. So i stopped it the first time at 12 inches and did 10 trials, then 24 etc.

would my initial velocity be zero?

Yes. If you hold the marble steady and release it carefully without pushing, your initial velocity is 0, so deltaV = the final velocity. Your starting point is a distance=0, so deltaD is equal to the measured distance (the length of the ramp or less if you started partway down).

Okay thank you very much for all your help

Follow up question:

what do you think are the best topics/ principles to discuss that are in relation to this experiment?

Even though you didn't use the video frame method of measuring speed and acceleration, you did manage to demonstrate the laws of motion and relationship between acceleration, velocity and distance traveled. The project doesn't go much further than the verification though, so I guess you'll have to concentrate and those relationships.

Maybe think about what would have happened if you did the experiment on the moon? Would your results have been different?