Is (0,0) a Valid Coordinate in a Bounce Height Experiment Graph?

[TheRedDevil18]

Hi, I just need some help with 3 questions that is asked in my rubric for this investigation. I have already done the experiment to investigate the relationship between the height from which a ball is dropped and the height of the resulting bounce

Homework Statement

1) Draw a graph of average bounce height versus drop height.
These 3 questions I am unsure about

2) Should (0,0) be included as a co-ordinate? Explain.
3) Should the line pass through (0,0)? Explain.
4) How does the gradient of the graph compare to the ratio of bounce height to drop height 110 cm and 55 cm respectively. This is called extrapolation. Clearly show on the graph how you obtained these values.

Homework Equations

The Attempt at a Solution

1) Done, got a straight line graph
2) Unsure, I would say no because the ball cannot be dropped from 0 height
3) Unsure, I would also say no
4) My gradient worked out to be 0.49 and the ratio 55/110 gives me 0.5 so I would say they are the same. To show it on my graph I would just extend the line?

 

[BruceW]

true, the ball cannot be dropped from 0 height. But maybe you can interpret it as meaning that the ball is not dropped. So when the ball is not dropped, how high does it bounce? It may be a silly thing to take note of, but I think the point is that for 2) you can choose whether to include this result or not. You just need to give an explanation of your choice.

And for 4) yes, that's right, extrapolation pretty much just means to extend the line, and see how close it comes to the point (55,110) (or (110,55) depending on which way round you are drawing your graph).

 

[TheRedDevil18]

If it is not dropped, you mean it is thrown then why do they give (0,0) as the co-ordinates, it should bounce to a certain height, really confused

 

[barryj]

On your graph, let the x-axis be the drop height and the y-axis be the bounce height. The bounce height is the dependent variable because the bounce height depends on the drop height, the independent variable. So, as you drop from various heights, wouldn't you think the graph should go through (0,0)? If you dropped a ball from a height of 0 then the bounce should be 0 right?