2) Science Investigation

Scientific Application:  

1. OBJECTIVES

1a.  Define “work.”

There are a lot of definitions for “Work”. However, the work that we are talking about now means when you move something a certain distance applying force.

 

1b.  Describe the units of measure for work.

The unit of measurement that is used to measure work is joules. However, when you write it in a form of an equation, you can write J to abbreviate it.

 

1c.  Use force and distance measurements to calculate work.

            As I mentioned before, work’s definition is when you move an item a certain distance applying force. That is why there is an equation to measure all of this, which is:

D (Distance in meters) x F (Newtons)= J (Joules)

 

2. INTRODUCTION

 

To most people, work is the physical or mental effort it takes to get something done.  If you ask a scientist, work takes a little more time to explain.  In this lesson, you will learn and use scientific definition of work and learn how to calculate work.

 You will make a number of measurements to use in calculating work.  Calculating is important in science.  This lesson will require you to use your math skills.  Good science combines facts and figures.  Mathematics is a great tool of science because it helps to describe how things behave and it helps scientists predict how some objects or processes will behave in the future.  Italian astronomer Galileo and English physicist and mathematician Sir Isaac Newton were among the first to realize the combined power of math and science.

In this lesson you will learn how forces do work and how to calculate the work done by forces.

 

3.  THE MEANING OF WORK

 

3a.  Discuss the meaning of the word work with your classmates, AND list examples of work being done.

 

We all found out in the previous section that work was when an item is moved a certain distance whilst applying force to it. We decided that some examples of work being done are:

–       Pulling a Sled up a hill for 5m

–       Pushing a barrel up an inclined plane that is 1 m long

–       Pushing a box for 3 meters

–       Pulling a Broken car up a hill that is 100m

 

3c.  After reading, review your examples of work and determine of they match the scientific meaning of work.

–       Pulling a Sled up a hill for 5m: This matches the scientific definition of work because you are pulling a sled for a certain distance using force.

–       Pushing a barrel up an inclined plane that is 1 m long: This is right because a barrel requires force to push and you are moving it for 1 m

–       Pushing a box for 3 meters: This is work because even though it is not going up a incline like the others, but it is moving a certain distance with force applied.

–       Pulling a Broken car up a hill that is 100m: The item that is moving is different because it has wheels but this is still work because it is moving a distance with force.

3d.  Write how to calculate a value for work and explain the units of measure for work.

As we found out in the previous questions work is calculated by first finding out the effort distance and the effort force. You calculate the value for work by putting your numbers in this equation:

D (Distance in meters) x F (Newtons)= J (Joules)

As you can see there is something called J which is an abbreviation for Joules. Joules is the term to measure work.

 

3e.  Work out this problem below, AND be sure to show your work.

 Q: Alice pulls a sled with a force of 12 N.  She pulls the sled through a distance of 5m.  How much work does Alice do on the sled?

A: 12N x 5m= 60 J

 

4.  HOMEWORK

4a.  What force are you working against when you lift a back pack?

The force that you are working against when you lift a backpack is called gravity. Gravity is something that humans cannot live without. Gravity is the force from the center of the earth that pulls everything to the ground. That is why when you drop something it doesn’t float in the air and it falls down. It’s the same for this situation. Gravity is pulling your backpack down and you are trying to work against it.

 4b.  In which of the following cases is work, as defined by scientists, being done?

i.  Someone tries to move a piano, but the piano won’t move.

            ii.  A truck is pulling a car slowly along a street.

iii.  A student is studying for a mathematics exam.

            iv.  A student is pushing a grocery cart around a store.

v.  Another student is standing in line at the grocery store holding a 12-N bag of potatoes.

vi.  A student pushes against the school building.

 

4c.  If you lift a bag that weighs 15 N a distance of 2 m, how much work have you done?

15N x 2m= 30J; 30 Joules

 

4d.  If a cement block that weighs 50 N must be raised to a height of 5 m, how much work must be done on the block?

50N x 5m= 250J; 250 Joules

 

5.  Summary Video

Khan Academy, Introduction to Work and Energy

 

6.  BIBLIOGRAPHY

Energy, Machines, and Motion. Burlington, NC: Carolina Biological Supply, 2006. Print.

 

1.  OBJECTIVES 

1a. Learn how an inclined plane works.

1b. Compare the work done in pulling an object up an incline with the work done in lifting the object straight up in the air.

Question 1a and 1b can be answered in the link below:

http://halimk.iics-k12.com/category/2-science-investigation/

 

2. Purpose

 Research Question: How does the angle of incline affect the amount of work?

 

What We Will Find Out: In this experiment we will measure the angle of incline and see how the amount of work in joules changes according to it. We will do this by pulling an item according to that angle with a spring scale to check this.

 

Hypothesis and explanation: If the angle of incline increases then the amount of work will stay the same because instead of the slope increasing, the effort distance will decrease. This cancels out any increases or decreases.

 

3. Variables

 

Independent variable: The angle of incline

 

Dependent Variable: amount of work (joules)

 

Controlled Variables:

– The item that is used.

– The inclined plane that is used.

– The vertical height.

– The system that is used to measure the rise run (cm).

– The system used to measure effort distance (m)

 

4. Method

Materials:

14 

– Inclined plane

– Spring scale (newtons)

– Filled water bottle

– 5 Books

– Meter stick

-Post it

 

Instructions:

1. Before you start the experiment, you should first make the table you will record the results in. First create 7 horizontal cells and 7 vertical cells. Now fill the first row with Trials, Rise, run, slope, effort Distance (m), Force (newtons), and Work (joules) respectively.

2. Now on the column of the trials name each of them 1st trial, 2nd trial… all the way to 6th trial.

3. Get out the materials (Inclined plane, spring scale, filled water bottle, books, post it, and meter stick)

4. First set the five books on top of each other and mark the point when the rise is 20cm.

5. Attach the spring scale with the water bottle and pull upwards so that the bottom of the water bottle reaches the 20cm mark.

6. Record the Rise (cm), run (cm), effort distance, and the force (newtons).

7. Now put the inclined plane on the books and make the slope gentle. When placing the inclined plane, remember that this is going to be your most gentle slope.

8. Mark the part of the inclined plane where the 20cm of the rise meets up with a post it.

9. Attach the spring scale with the water bottle and pull it up the inclined plane steadily until the point where the post it is.

10. Record the Rise (cm), run (cm), effort distance, and the force (newtons).

11. Make the inclined plane steeper than before but not quite because it is your second gentlest slope.

12. Mark the part of the inclined plane where the 20cm of the rise meets up with a post it.

13. Attach the spring scale with the water bottle and pull it up the inclined plane steadily until the point where the post it is.

14. Record the Rise (cm), run (cm), effort distance, and the force (newtons).

15. Move the inclined plane slightly up then it was before. (This is the third gentlest slope)

16. Mark the part of the inclined plane where the 20cm of the rise meets up with a post it.

17. Attach the spring scale with the water bottle and pull it up the inclined plane steadily until the point where the post it is.

18. Record the Rise (cm), run (cm), effort distance, and the force (newtons).

19. Move the inclined plane up a little more so that there is room for one more experiment after.

20. Mark the part of the inclined plane where the 20cm of the rise meets up with a post it.

21. Attach the spring scale with the water bottle and pull it up the inclined plane steadily until the point where the post it is.

22. Record the Rise (cm), run (cm), effort distance, and the force (newtons).

23. Move the inclined plane up more; this is going to be the second steepest slope after the one pulling straight up.

24. Mark the part of the inclined plane where the 20cm of the rise meets up with a post it.

25. Attach the spring scale with the water bottle and pull it up the inclined plane steadily until the point where the post it is.

26. Record the Rise (cm), run (cm), effort distance, and the force (newtons).

27. Now that the experiment is finished calculate the Slope and record it on the table.

28. Now that the slope is calculated let us calculate the Work (joules) by using the equation: D (m) X F (Newtons)= Work (joules); record the data.

29. Now that the table is finished, we have to make the graph. Open excel and post in the first column the data for the slope and in the other the data for the work (joules). Highlight it all and click on “Charts”-“Scatter”. Now that the scatter plot is formed, we have to make the line of best fit that can be made by going in to “Charts”-“Chart Layout”- “Trend line”- “Linear trend line”. For an addition I decided to make an equation to go with the trend line. To make an equation, go to “Trend line”-“Trend line options”-“Display equation on chart”.

 

Photos of experiment:

 

Data Collection and Data Processing:

a) Table

 

Trials

Rise (cm)

Run (cm)

Slope

Effort Distance

(m)

Force (newtons)

Work (joules)

1st

20

0

Undefined

0.2

6

1.20

2nd

20

72

0.28

0.73

3

2.19

3rd

20

62

0.32

0.64

3.5

2.24

4th

20

52

0.38

0.54

3.5

1.89

5th

20

45

0.44

0.47

4

1.88

6th

20

42

0.48

0.46

4

1.84

b) Graph

 ggggg

***Note that one point could not be plotted on the graph because the slope was undefined.

 

c) Analysis and Explanation of graph and table

First of all, in the table, you can see a lot of quantitative data. One can say that the data is very well organized and they are easy to look at to find patterns between the numbers. For example we can see in the rise (cm) column, the rise always stays the same that can’t be seen in the graph. One can identify from the data that the slope is decreasing gradually because it decreases about 10-30 joules each time. However, it is not very clear in the table and it takes a while for people to identify the right variables from the pile of information. One thing how the table is better is the point that you can see the undefined slope’s data but in the graph you cannot.

In the graph we can see in estimate on where the work (joules) and slopes are and it is not as clear as in the table. However, the pattern is clearer in the graph than the table. The line of best fit shows this pattern. The line of best fit is a line that draws a rough linear relationship between the scattered points. One can see in the graph that the linear relationship between the points is decreasing every time the slope increases (increase of steepness). For an extra, I put the equation of the line that is also a helper in to finding the pattern to the data. The equation of the line is: y= -2.0809x+2.7987. From this equation -2.0809x is the slope and in math when the slope is a negative number the line is a declining line. Therefore from there we can also see the pattern of the data is declining.

 

Overall, from the table and the graph we can find out that in this experiment, that the relationship between slope and work (J) is that as the slope increases work decreases.

Evaluation and Conclusion

Hypothesis Validity:

 

In my hypothesis I stated:

 

If the angle of incline increases then the amount of work will stay the same because instead of the slope increasing, the effort distance will decrease. This cancels out any increases or decreases.

 

To sum my hypothesis up I wrote that there wouldn’t be any differences to the data, no increases or decreases. However, my data shows that there was a decrease and this is not the same as what I stated in my hypothesis. At first I wondered if my hypothesis was right or if my experiment was right. We had a discussion in class and I found out that my hypothesis was right. There fore there are some parts that I can improve in my experiment and they are listed bellow.

 

 

Reliability:

 

In my experiment, I think reliability is a point that it can improve on. Reliability is a point that talks about if the measurement that I did was correct and if they are proven right from several trials. When I measured the force with my spring scale, when the data was somewhat in the middle, I would round it up. For example in the 5th trial I rounded up the somewhat 4.5 Newtons to 5 Newtons. Because I did things like this often, they added up and made a difference to my experiment. Another reason my reliability could have been better is because I didn’t measure it multiple times. Because I was in a hurry, I only measured the force the effort distance etc. Once and didn’t think of measuring it more than one time to check if I was using the spring scales right. Again, this might have affected my experiment because I might have had some errors when I was calculating the force. However, a ting that I did good in reliability that I double-checked if the slope was right. For example, when one tries to calculate the slope they have to do rise over run. Even if a calculator does this, this might go wrong because I might have typed a wrong number. When I am dealing with numbers I checked again and again to see if I was right and all of the times they were right.

 

Improvements (Reliability):

 

Because Reliability is a point that I have to improve on, there are a lot of things that I have to list. First of all, I mentioned in the previous paragraph that I would round up the numbers and not do the precise number. I mentioned specifically about the force measuring and the spring scale. I said that the force was often near the middle. What I can do to fix this is a) find a spring scale that has more lines on it so I can know better how much force there are or b) Try this multiple times so that I can find out how many times it stays on which number so even though it is rounding up or down, it is more precise. I could also add more columns to write trial 1 3 times so there can be more precise data and an average.

 

Validity:

 

Even though the reliability of my experiment has a lot of areas where it can be improved, in the point of validity, I did a very thorough job of one of the hardest control variables that is the vertical height. I decided that the vertical height should always be 20cm. Before I started each experiment I measured the vertical height multiple times to mark the inclined plane. If the vertical height would be wrong, then the other data will fall apart because it will affect the slope since it is the rise as well. Another way that my Validity is good is because once I got confused with what unit to use that are my control variables. At first I used cm for everything then I realized that the answers were a little too high. I asked Ms. MacFarlane and she told me to measure in meters. That way I kept to my control variable so that it will not affect my independent or dependent variable.

 

Improvements (Validity):

 

Even though I mentioned some good things about validity, there are still a lot of things that can be improved in my experiment in the aspect of validity. For example, one of my control variables was the water bottle. However, to make the water bottle work with the spring scales, I had to put water in it. If I had done this experiment two separate times, the amount of water I put in the water bottle might have affected the results to the second set of tests which might hide the results. I think a good solution for this can be that I use an item that the weight cannot be easily changed.

 

Further inquiry:

 

There are a lot of things that I would do to change or expand this experiment. One thing that I would change in my experiment to make it more interesting is to add more math to this experiment. Instead of the independent variable being slope, we should make this so that it is actually the angle of incline. We can do this by using trigonometry. Another way that I would change this experiment is that I would do one that we can change the rise and not keep it the same all the time. A way I would expand this experiment is doing more trials. I have done 6 trials and I do not believe that to be a good amount to decide anything from. Doing more trials will give us a more precise and accurate data. A good way to expand this experiment is to combine the data of the whole class and make a graph and table out of that. Again, this would be a great opportunity for students to find out the precise data. One last way that I thought of to expand this experiment is to find out if items with wheels use less work than ones without wheels.

Comparing Graphs:

 

a) My Graph and Table

Trials

Rise (cm)

Run (cm)

Slope

Effort Distance

(m)

Force (newtons)

Work (joules)

1st

20

0

Undefined

0.2

6

1.20

2nd

20

72

0.28

0.73

3

2.19

3rd

20

62

0.32

0.64

3.5

2.24

4th

20

52

0.38

0.54

3.5

1.89

5th

20

45

0.44

0.47

4

1.88

6th

20

42

0.48

0.46

4

1.84

ggggg

b) Sample Graph and Table

Slope Work

0.14

0.61

0.21

0.64

0.27

0.59

0.34

0.53

0.41

0.57

bbbbb

In the Inclined Plane sample data one can see that the result is similar to how I stated in my hypothesis. I stated that there will be no increase or decrease and the work will be constant. One can see that work is always in the range of 0.5-0.6, which is in a very similar range. The results that I found in my graph is that the work decreases as the slope of the ramp increases. One can see this by the trend line and how the equation’s slope is a negative. One of the main reasons the height of where the dots are are different is because my data is a raise 0f 0.2m whilst the sample graph is 0.1.

 

I think the two data’s are different because my data had a lot of disruptions in the middle. For example, as mentioned before, when I was experimenting and recording the results, I rounded a lot of numbers up so that it would be easier for me to record and calculate. However, the results found out in the sample graph match my hypothesis and therefore I can state that my hypothesis is right.

 

3.  Questions

 

3a.  On the basis of the results of these inquiries, how would you define a machine?

I would define a machine as something that makes work easier for humans because as I realised when I was experimenting I think that simple machines were not just made out of nowhere. It was found or created so that humans could interact with them a benefit from them.

3b.  In your view, is an inclined plane a machine?

In my view I think that an inclined plane is not a machine firstly because it can be found in the environment and second because it doesn’t make work easier for humans. It can be found in the environment in forms of different things such as mountains and hills. I found out that it doesn’t make work easier for humans and the work amount stays the same because as the slope increases the effort distance decreases and vise versa so they each get cancelled out.

 3c.  Why are ramps for people with physical disabilities long and gently sloping, rather than short and steep?

If the Ramps were too steep the speed of the wheel chair going down will increase which will create a higher possibility of their being an injury.

4.  BIBLIOGRAPHY

Energy, Machines, and Motion. Burlington, NC: Carolina Biological Supply, 2006. Print.