# Investigation between the relationship of Mass and Time taken while coming down a water slide.

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Introduction

Investigation between the relationship of Mass and Time taken while coming down a water slide

In this experiment I am going to investigate the relationship between Mass and Speed of 5 people with different masses coming down a water slide. Firstly, I have obtained evidence by measuring the time taken for people with various different masses to come down a water slide. My prediction is that mass is independent of the time taken. We have used a digital stop watch to measure the time taken of the people coming down the slide. I am going to use several different scientific equations to try and prove my prediction. I also have to take into consideration that the slide is not a straight surface it has several different bumps but I also predict that this has no effect to the time taken as horizontal velocity is independent of vertical velocity because both of these masses are being pulled by gravity at a constant acceleration of 9.8m/s²so all objects free fall at the same rate of acceleration regardless of their mass.

I have tabulated my results according to the different Masses in

Middle

Lian | 9.78 m/s | Omar | 9.42 m/s |

Abhay | 9.69 m/s | Alan | 9.69 m/s |

Calculating the height of the slide

Although we were given the length of the slide I will show how they had calculated by using Pythagoras theorem which says in a right angle triangle the sum of squares of the base and the height is equal to the square of the hypotenuse.

X² = 55² + 50² I cannot be certain if this is the correct

X² = 3025 + 2500 as the slide was not a triangle but I am

X² = 5525 going to carry the error forward to do

X= 74.3 all calculations.

From these results I can rule out the inference, the greater the persons mass the slower a person will go down or faster! This is false because Alan has a greater mass than Omar but his average time was still smaller than Omar’s who has a smaller mass and had a larger time taken.

Back to my prediction which is in a straight that Mass is independent of time taken. To prove this I will use my equation h = ut + ½gt², this is the equation is used whenever an object travels at a uniform acceleration line where h = height, u = initial velocity, v = final velocity, t = time taken and g = acceleration due to gravity which is 9.8 m/s², As you can see mass does not play any role in this equation it is only acceleration that does as it is the acceleration due to gravity.

Conclusion

Variation of results:

I am now going to work with the average time taken for the 4 different masses to show you how minor the changes are.

Let’s take Lian who has a mass of 50 kg and whose average time taken was 7.56 and let’s take Alan who has a mass of 64 kg and whose average time taken was 7.63.The difference in mass is 14 kg and the difference in time taken was 0.07 seconds! Even after such a great increase in mass there has hardly been any difference in the time taken.

Let us now take Abhay with a mass of 58 kg and Omar who has a mass of 60 kg which is only a 2 kg change in the mass which is far smaller than the change with Lian and Alan. Abhay’s average time taken was 7.63 and Omar’s average time taken was 7.85, the difference in time taken was 0.22 seconds.

By using these results I can help prove my prediction saying that mass is independent to time taken.

Improvements

To improve the experiment we should have had a straight slide instead of a parabolic surface to be able to calculate the length of slide more accurately using Pythagoras’ theorem.

We could have used light gates instead of stop watches to get exact readings when students start and stop on the slide this way they could avoid any human error.

Each person could have used the same float as they can all encounter the same % of friction.

We could have used different slides to test the effect of friction on different surfaces.

This student written piece of work is one of many that can be found in our GCSE Forces and Motion section.

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