Graphs (2 Viewers)

[Green Yoda]

So I have a Practical Test tomorrow and my friend told me that there is going to be a graph and it has something to do with newtons, force and acceleration. So can you give me tips on how to make a good graph and what to include in it? The section also has questions about variables. Can someone also explain the different variables with examples please?

 

[Kittyrules]

ok so, lets say the experiment you are doing is attaching a different mass onto a spring and seeing how many newtons of force it has. just as an example

independent variable = the thing you change in your experiment. i.e the mass. you change it from 0g, to 100, 200g, to 300g etc

dependent variable = this is the thing you measure. i.e the newtons. this is the stuff you write into your table of data

controlled variable = this is everything else, that for good scientific method, STAYS THE SAME. and is controlled. for example, the height at which you hold the mass, the tempurature of the room, the amount of time, the set-up, the type of material, etc etc. it really depends on the context. the thing is with the controlled variables is that they often can create error, because they are not accounted for properly.

with a graph, remember to put in:
- axis names and units in brackets e.g Force (N), Acceleration (ms^-2), Mass (kg) etc
- title of graph e.g Force vs Acceleration
- your independant variable on the x axis (horizontal one)
- a line of best fit. this is not a line that simply joins dots, but is at an average distance between all points. so you might have 3 points above it, and 3 points below. make sure your line of best fit does not go further than the data you have recorded/been given. If you so, you might be penalised, and you should do it with a dashed line. Remember it might not be straight all the time! it might be curved (but i doubt that in yr 10 they'll give you that)
- mark your points with crosses
- when you claculate a gradient, calculate it from your line of best fit, not from your points
- use at least 70% of the graph paper you are given

and thats all i can think of right now....i had my phys prac test yesterday haha

good luck!

 

[Green Yoda]

ok so, lets say the experiment you are doing is attaching a different mass onto a spring and seeing how many newtons of force it has. just as an example

independant variable = the thing you change in your experiment. i.e the mass. you change it from 0g, to 100, 200g, to 300g etc

dependant variable = this is the thing you measure. i.e the newtons. this is the stuff you write into your table of data

controlled variable = this is everything else, that for good scientific method, STAYS THE SAME. and is controlled. for example, the height at which you hold the mass, the tempurature of the room, the amount of time, the set-up, the type of material, etc etc. it really depends on the context. the thing is with the controlled variables is that they often can create error, because they are not accounted for properly.

with a graph, remember to put in:
- axis names and units in brackets e.g Force (N), Acceleration (ms^-2), Mass (kg) etc
- title of graph e.g Force vs Acceleration
- your independant variable on the x axis (horizontal one)
- a line of best fit. this is not a line that simply joins dots, but is at an average distance between all points. so you might have 3 points above it, and 3 points below. make sure your line of best fit does not go further than the data you have recorded/been given. If you so, you might be penalised, and you should do it with a dashed line. Remember it might not be straight all the time! it might be curved (but i doubt that in yr 10 they'll give you that)
- mark your points with crosses
- when you claculate a gradient, calculate it from your line of best fit, not from your points
- use at least 70% of the graph paper you are given

and thats all i can think of right now....i had my phys prac test yesterday haha

good luck!

You are a legend mate!

 

[Green Yoda]

Also do the graph have to be linear? so for example my x axis is the mass and my y axis is newtons, the mass goes up my 100 grams, does the newtons have to go up my same number?

 

[InteGrand]

Also do the graph have to be linear? so for example my x axis is the mass and my y axis is newtons, the mass goes up my 100 grams, does the newtons have to go up my same number?

(Bolded word should be 'scales'.) That's not the meaning of a linear scale. Linear scale means that the value on the axis is proportional to the distance travelled along the axis.

You do need both axes to have linear scales, but they need not be the same scale. (You were asking whether they need the same scale.)

(Incidentally, the spellings are 'dependent', and 'independent'.)

 

[Kittyrules]

(Bolded word should be 'scale'.) That's not the meaning of a linear scale. Linear scale means that the value on the axis is proportional to the distance travelled along the axis.

You do need both axes to have linear scales, but they need not be the same scale. (You were asking whether they need the same scale.)

(Incidentally, the spellings are 'dependent', and 'independent'.)

LOL thankyou, noted and changed XD i honestly cannot spell them correctly ever.

 

[InteGrand]

Also, you are allowed to place the independent variable on the horizontal axis, and dependent variable on the vertical axis, if this is more convenient in terms of making the gradient what you want in order to calculate some physical value. HOWEVER, if you do so, you must write a note next to your graph somewhere, saying something like "Note. Independent variable plotted on horizontal axis in order to make gradient calculation convenient".

And remember to include units for your gradient, if it has units (in general, its units are (units of y-axis)/(units of x-axis)).

 

[Green Yoda]

I don't think there will be gradient and stuff in the exam. I heard its gonna be the weights on spring and how much force experiment. Any tips on this experiment and graphing it and it's variables?

 

[InteGrand]

Remember to plot the points as crosses.

 

[sy37]

Remember: ICDMCS ---> { I can't do maths, calculations, science } --> Independent Change, Dependent Measure, Control Same

For your results, don't forget to talk about outliers, if any (In my prac exam, I actually faked an outlier for more discussion / analysis depth). If you're running out of time, fake results (it should be obvious, most things are either proportional or inversely proportional). If there are calculations you need to do, do those first.

I got 96% for my 2hrs~ prac exam measuring solar cells, light intensity, absorption etc doing the above. Most important thing is *fake it till you make it* - seriously they can't detect fake results esp. if the theory checks with it.