Mass Tipping a Plank: Independent & Dependent Variables + Data

[uniquegirl]

Homework Statement

Carry out your own investigation into the relationship between the mass of an object on a plank (𝑚𝑚) and the distance from the fulcrum (𝑑𝑑) at which it will cause the plank to tip.

Relevant Equations

You will use a ruler to model the plank and a pile of quarters (6) to model the mass of the cyclist. Set up the ruler so that the coin is just on the point of tipping the ruler. Once the ruler is positioned, do not move it. Vary the mass of the pile of coins (by adding more coins). Move the coins (not the ruler) to find the new tipping point.

https://www.physicsforums.com/attachments/1567809385305-png.249313/

Can someone tell me what the Independent and Dependent variable is? And what is the data I'm supposed to collect? Is it the distance when the coins tip or is it the mass of the coins? Please help!

 

[kuruman]

Set up the ruler so that the coin is just on the point of tipping the ruler. Once the ruler is positioned, do not move it. Vary the mass of the pile of coins (by adding more coins). Move the coins (not the ruler) to find the new tipping point.

Hi @uniquegirl and welcome to PF.

The instructions clearly state what you are supposed to do. The independent variable is the number of coins which proportional to the mass $m$ on the ruler. The dependent variable is the tipping distance $d$. You are free to choose any number of coins to put on the ruler. That makes the mass $m$ the independent variable. However, once you make that choice, there is only one tipping distance $d$. That makes $d$ the dependent variable. In other words, the value of $d$ depends on your choice of the value of $m$.

 

[uniquegirl]

Hi @uniquegirl and welcome to PF.

The instructions clearly state what you are supposed to do. The independent variable is the number of coins which proportional to the mass $m$ on the ruler. The dependent variable is the tipping distance $d$. You are free to choose any number of coins to put on the ruler. That makes the mass $m$ the independent variable. However, once you make that choice, there is only one tipping distance $d$. That makes $d$ the dependent variable. In other words, the value of $d$ depends on your choice of the value of $m$.

Thank you so much for your reply. When I do my graphs, I use the mass of the coin (for example 5g) vs the distance (eg: 3cm)? Not how many coins I used right? So each time I add a new coin it increases in mass. When there are 2 coins the mass would be 10g etc.
Also what type of relationship do you think it is? (Inverse Relationship, Square Relationship etc)

 

[erobz]

Thank you so much for your reply. When I do my graphs, I use the mass of the coin (for example 5g) vs the distance (eg: 3cm)? Not how many coins I used right? So each time I add a new coin it increases in mass.

It won't matter mass or number of coins ( assuming they are identical coins ), but the problem statement wants you to use mass.

Also what type of relationship do you think it is? (Inverse Relationship, Square Relationship etc)

That is the objective ( to determine a relationship). You should run the experiment to find out. It doesn't hurt, to make a prediction, but is should be your prediction you are testing. What model you can come up with to make your prediction is going to depend a little on how much physics you know?

 

[kuruman]

To get the dependence of the

Thank you so much for your reply. When I do my graphs, I use the mass of the coin (for example 5g) vs the distance (eg: 3cm)? Not how many coins I used right? So each time I add a new coin it increases in mass. When there are 2 coins the mass would be 10g etc.
Also what type of relationship do you think it is? (Inverse Relationship, Square Relationship etc)

No, you plot the distance vs. mass or number of coins. What follows "vs." is the independent variable and is placed on the horizontal axis.

 

[Lnewqban]

Can someone tell me what the Independent and Dependent variable is?

Welcome!
Please, see:
https://www.wikihow.com/Identify-Dependent-and-Independent-Variables

 

[uniquegirl]

Thank you guys so much! you guys are life savers :)