Student Worksheet Simple Machines - Lesson 1: The Wedge and Lever Name(s):____________________________ ___________________________________
Talk Now - 1a: Shape of the wedge With your lab partner, predict how the shape (proportion) of the wedge might influence its effectiveness. Write your prediction here:
Lab Instructions: 1. Select a length for your wedge. The width will remain at 12 cm. 2. Record the length of your first wedge and the force - or weight (N) - that was applied. 3. Repeat this using 6 to 8 different lengths Data Collection:: Table 1: Wedge Length(cm)
Talk Now - 1b: Effectiveness of the wedge Do you notice any patterns to help you predict how much weight will break the stone? Write a general statement explaining which wedges will work most efficiently.
Data Analysis -1: To look at this information in another way, make a line graph showing the wedge dimensions you have tested. Remember, the width is fixed. 20 19 18
Width – cm
17 16 15 14 13 12 11 10 9 8 7 6 5
Length – cm Label your axis in the space above Use a second graph to look at the force required for all wedges you tested. 20 19 18
Length – cm
17 16 15 14 13 12 11 10 9 8 7 6 5
Add a label for value in the columns below
Force - weight(N)
Analysis questions: 1. Using the data from your chart and your graph, write a general statement about the length and width of the wedges that did the work most efficiently.
2. Make a prediction of what might happen with extreme shaped wedges. i.e.: an extremely long wedge or a very short, almost-flat wedge. Might there be problems at both extremes? Explain your prediction.
3. How did the force which was applied to the wedge change as you changed the length of the wedge?
4. What is the relationship between the wedge length and the force required to use it?
5. Refer back to your prediction at the beginning of this lab. How might you change your statement to be more accurate or more complete?
Let's move on to the Lever: Talk Now – 1c: Predicting the effectiveness of a lever With your partner, discuss predict how a lever might be used to make work easier. Together, form an answer for the following question and write it down: How will a lever make lifting the block onto the sled easier for Harry?
Lab Instructions: The Lever 1. Select a placement for the fulcrum and record your data. 2. Record effort distance, effort force and indicate whether or not it was successful. 3. Repeat using various fulcrum placements. Data Collection:: Table 2: Lever Effort Distance(DE)
1 2 3 4 5 6 7 8 9 10 Talk Now – 1d: Predicting and testing success Predict fulcrum placements which will not be successful. Explain why you think these placements won't be successful. Use complete sentences.
Test your prediction (hypothesis.) Do you want to add to your prediction or change it a little?
Data Analysis - 2: Use your data from Table 2 to create a new table showing work done. Use the data from successful attempts. Calculate: Effort Distance (m) x Effort Force(N) = Work (J) Table 3: Lever – work done Effort Distance (m)
X Effort Force(N)
1 2 3 4 5 6 7 8 9 10 Analysis Questions: 1. What do you notice about the amount of work done in each successful trial?
2. Compare the effort distance(DE) and effort force (FE) in all trials. What happens to the amount of FE as the DE increases?
3. Use the term “inverse” or “direct” to explain the relationship between FE and DE as you adjusted your lever. (Use complete sentences.)
4. What are the advantages of using a lever to lift this stone?
Data Analysis – 3: Use the same data again to complete Table 4 which will help us look at mechanical advantage. When you have filled in the data, calculate the MA both ways for each successful test. Table 4: Mechanical Advantage Force of Rock(FR) / Effort Force(FE)
Effort Distance(DE) / Distance of Rock (DR) =
Analysis Questions: 1. What conclusions can you draw from comparing the MA using the forces and the MA using the distances for each trial?
2. a) Comparing different trials: As the effort distance (DE) increases, what happens to the MA?
b) What happens to the effort force (FE)?
Talk Now – 1e: Summarizing your conclusions Create a statement explaining the advantage of using a lever to lift a heavy mass:
Refer back to your prediction at the beginning of the lever lab. How might you change your statement to be more accurate or complete?
Brainstorm a list of ways that a lever might be used in your world today:
Student Worksheet Simple Machines – Lesson 2: The Inclined Plane and Pulley Name(s):____________________________ ___________________________________
Talk Now – 2a: Inclined Planes With your partner, think of as many examples of inclined planes as you can. Record your list.
Lab Instructions 1. Select a length for the inclined plane. 2. Record the length, effort force and indicate whether or not it was successful. 3. Repeat using various lengths. Data Collection:: Table 1: Inclined Plane Inclined Plane Length
1 2 3 4 5 6 7 8 Analysis Questions - 1: 1. From your chart of data, find the maximum effort our crew member can sustain to pull the stone up from the inclined plane.
2. What is the length of this inclined plane?
3. Would this be the ideal length to use for the inclined plane?
4. What other factors might you consider?
Talk Now – 2b: Discuss the inclined plane optimal length Defend your choice for the ideal length. Give your reasons in complete sentences.
Data Analysis - 1: calculate work done with inclined plane Transfer the data for length and effort from Table 1 onto Table 2. Calculate the amount of work done to get the stone to the top of each inclined plane. Remember: Work = Force applied X distance mass is moved. Table 2: Incline Plane work done Effort Force(N) X Distance(m) = Work Nm(J) 1
2 3 4 5 6 7 8 How do the values of work found for the various lengths of inclined plane compare? Use complete sentences in your answer.
Graphing Data - 1:: Label the graph and plot the data from Table 1:
Length 1. Describe the arrangement of points on your graph in words:
2. What happens to the effort force needed as the length of the inclined plane increases?
3. What do we call this kind of relationship?
4. Using the information you have just collected, in your own wors explain the advange gained by using an inclined plane to raise an object:
The Wedge Connection: Talk Now - 2c: Harry's Ramp Confer with your partner and make a list of how the wedge and the inclined plane are similar. (Be sure to consider both form and function.)
1. What happens to the stone as Harry pushes the inclined plane?
2. In what direction is Harry applying the force?
3. In what direction is the force acting on the stone?
4. What is moving the most, the inclined plane or the stone?
Talk Now – 2d: which force is greater? Discuss what you have just done with your partner: Remember: Work = force X distance the force moves. Predict which force is greater: the force Harry is applying to the magical weightless inclined plane or the force acting on the stone? Explain your answer using complete sentences.
Talk Now – 2e: The Pulley Why do you think that Pic's experiment worked? Discuss this with your partner, then record your best explanation using complete sentences.
Lab Instructions: Record the number of supporting ropes, the effort force applied to the rope, and the distance the rope is pulled on Table 3. Record the data for all 4 available arrangements. Calculate the work input for each trial on Table 3 by multiplying the force applied by the length the rope was pulled. Data Collection:: Table 3: The Pulley # of supporting ropes
Length of rope pulled(m)
Compare your 4 values for work, and using complete sentences describe what you found.
Data Analysis – 2: Table 4: calculate the Pulley MA Transfer the data needed from Table 3 to Table 4 and calculate the mechanical advantage(MA) for each of the pulley systems used. # of supporting ropes Resistance Force / Effort Force = MA 1
Talk Now – 2F Use complete sentences to describe the relationship between the # of supporting ropes and the mechanical advantage of a pulley system.
# of Supporting Ropes
Graphing Data – 2:: Graph 2A - Use the number of supporting ropes and thelength of rope used to lift our stone to complete Graph 2A. 7 6 5 4 3 2 1 1m 2m 3m 4m 5m 6m 7m 8m 9m 10m Analysis Questions: 1. As the number of supporting ropes on the pulley increases, what happens to the length of rope that must be pulled to lift the stone into place?
2. Using this graph, predict the length of rope that would be pulled if you were using 5 supporting ropes.
Graph 2B - Use the force applied in each test and the length of the force pulled to complete Graph 2B: Length of Ropes(m)
7 6 5 4 3 2 1 500 1000 1500 2000 2500 3000 3500 4000 4500 5000
Analysis Questions 1. As the amount of force increases, what happens to the length of rope pulled?
2. Predict the force if the length of rope pulled had been 7 meters.
# of Supporting Ropes
Graph 2C -Use the number of supporting ropes and the force applied to complete graph C. 7 6 5 4 3 2 1 500 1000 1500 2000 2500 3000 3500 4000 4500 5000
Analysis Questions 1. As the number of supporting rops increases, what happens to the amount of force applied?
2. Predict the force needed if 5 supporting ropes were used.
3. Was this prediction as easy to make as the predictions using graphs A and B? Explain your answer using complete sentences.
Talk Now – 2g: Graph analysis With your partner, compare the patterns formed by the points on each of the graphs. Using complete sentences describe the pattern of each graph and what that pattern tells you.
Talk Now – 2h: The Ramp & the Pulley With your partner discuss all of the variables available in this type of combined system. (What kinds of things could you change?) List the variables you thought of and explain what each type of change would do to the mechanical advantage. Be sure to answer using complete sentences.
Lab Instructions: Select a length for the ramp by dragging the tip of the ramp to the length you choose. Test each of the four possible pulley selections for this ramp and record the information on Table 5. Select a different length for the ramp and test each of the pulley selections. Record this data in Table 5 also. Data Collection:: Cooperation Table 5 – The Ramp & The Pulley # of supporting ropes Length of Ramp
MA Resistance/effort Force
1 2 3 4 1 2 3 4 As a reminder to get MA, the weight or resistance of our rock is fixed at 3480 N. Weight / Effort Force = MA
Analysis Questions 1. In each trial, how does the input force compare to the weight of the stone? Weight [Resistance force (3480 N)] divided by effort force equals mechanical advantage
2. Calculate the system mechanical advantage for each of your tests. • Select one line of data from Table5 • Calculate the MA of the inclined plane [ramp length divided by ramp height (1.3)]: • Calculate the MA for the pulley system • Select a second line of data from table 4 and calculate the MA for the inclined plane and the pulley as you did above. Work space:
3. Compare these values with the MA you recorded for the same systems on Table 4.
Talk now – 2i: Discuss your results with your partner. Using full sentences, describe what happens to the mechanical advantage when you combine simple machines.
Challenge: Design 2 different inclined plane and pulley systems which will allow Pic and Harry to each raise a stone the same distance while using the same effort forces.
Student Worksheet Simple Machines – Lesson 3: The Wedge and the Lever Name(s):____________________________ ___________________________________
Talk Now - 3a: Predicting with the screw If this inclined plane moves 3 cm to the left, how high will it lift the object?
How do you predict the force applied to the resistance compares to the force you must apply to the screw?
Lab Instructions: Record the effort force, the distance lifted and the thread density for 5 tests. We will explore the wheel diameter in another lab, so leave it fixed during these tests for now. Data Collection:: Table 1: The Screw & The Axle Effort Force
1 2 3 4 5 6 7 8
Graphing - 1:: Use the data from Table 1 to complete these graphs.
Distance wheel is turned
Number of threads/cm Analysis question: 1. As the number of threads per centimeter increases, what happens to the distance the wheel is turned to lift the gate?
Effort Force (N)
Number of threads/cm 2. As the number of threads per centimeters increases, what happens to the amount of force needed to turn the wheel?
Talk Now – 3b: discuss thread density Discuss the relationships shown on graphs A and B with your partner. In your own words explain how an increase in the thread density changes the distance the wheel is turned and the amount of effort force needed to lift the slab. Be sure to use complete sentences.
Talk Now – 3c: the wheel and axle With your partner, list as many possible reasons why they used a wheel to turn the screw instead of a screwdriver.
With your partner predict what changes might occur when you adjust the wheel's radius. Record your prediction.
Lab Instructions: • Select a wheel size and record the effort applied, distance lifted and wheel radius in your lab packet. • Repeat this test using at least 4 different radii. • Record data from each test before going on. Data Collection:: Table 2 – The Wheel & Axle Effort Force
Graphing – 2:: Use the data from Table 2 to complete graph C
Effort Force (N)
Radius 50-100 Analysis Questions: 1. What happens to the effort force as the radius increases? Use complete sentences.
2. Compare these results with your predictions. Use complete sentences.
3. If an increase in the length of an effort arm results in a decrease in the effort force, explain why an increase in the radius of a wheel results in a decrease in effort force needed.
4. As the radius of the wheel increases, what happens to its circumference?
5. How does this change the distance the handle moves to make one full rotations?
6. What would you gain if you applied the effort force at the axle instead of at the outside of the wheel?
Talk Now – 3d: Machines in Combination Discuss with your partner. You have seen that adjusting thread density will change the amount of effort force needed and adjusting the wheel radius will also change the amount of effort force needed. Explain in your own words the advantage of combining these two simple machines. Use complete sentences.
Challenge: Predict 3 different combinations of thread density and wheel radius which will allow the gate to be lifted using the same effort force.