Activity 2.4 Energy in, energy out
Equipment needed: Each GROUP will require:
standard set of laboratory single, double and triple-sheaved pulleys
retort stand with boss heads and clamps
string
slotted masses
set of spring balances
metre ruler
Experiment 1: Single sheaf pulley Instructions: Set up a single pulley as shown in the diagram for Pulley 1. Place different masses on the load side of the pulley and measure the force required to lift it. At the same time, measure the height the load is lifted and the distance the effort string has to be pulled.
Results: Mass of load (kg)
Weight of load (N)
Distance of load (m)
Effort (N)
Distance of effort (m)
Pulley 1
Conclusion: How did the force needed to pull down compare to the load you were lifting?
What did this pulley achieve?
Energy • Activity 2.4 Energy in, energy out
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Activity 2.4 Energy in, energy out
Experiment 2: Single-sheaf pulley Try the same with Pulley 2, a different arrangement of a single-sheaf pulley. What did this pulley achieve? What did you notice about the distance of the effort and load? Multiply the effort force by distance and the load force by distance to compare how much work was put into the pulley and how much work you got out of it.
Results: Mass of load (kg)
Weight of load (N)
Distance of load (m)
Effort (N)
Distance of effort (m)
Pulley 2
Energy • Activity 2.4 Energy in, energy out
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Activity 2.4 Energy in, energy out
Experiment 3: Multiple-sheaf pulley Instructions: Set up a pulley system using two single-shear pulleys, as shown in the diagram. Repeat Experiment 1 using this new system. Take the same measurements and fill in the first row of the table. Work is the mechanical energy transferred through the pulley, from the effort to the load To calculate work, use the formula: work = force x distance Work is measured in Joules (J), force is measured in Newtons (N), and distance should be measured in metres (m). Now calculate the Mechanical advantage (MA) of the pulley. Mechanical advantage = load/effort Results: Mass of load (kg)
Weight of load (N)
Distance of load (m)
Work in (J)
Effort (N)
Distance of effort (m)
Work out
MA
(J)
Pulley 3
Energy • Activity 2.4 Energy in, energy out
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Activity 2.4 Energy in, energy out
Experiments 4 and 5: Complex pulleys A pulley system using multiple sheafs is often called a block and tackle. A block and tackle might be used to lift a motor from a car or a boat. Large container ships are unloaded by enormous gantry cranes, which still use pulley systems to lift heavily loaded containers. Now design two more complex pulleys using double- and triple-sheaf pulleys. Draw the systems you have designed here. Label them Pulley 4 and Pulley 5.
Results: Mass of load (kg)
Weight of load (N)
Distance of load (m)
Work In (J)
Effort (N)
Distance of effort (m)
Work out
MA
(J)
Pulley 4 Pulley 5
Conclusion: What conclusion can you make about how pulleys multiply force?
In your standard pulleys, where both the effort and the load are pulling down, how could you work out the MA from counting the number of strings?
Energy • Activity 2.4 Energy in, energy out
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Activity 2.7 Putting it together (Quiz)
You may refer to your Notebook. Question 1 (Energy forms) Name six different forms of energy and provide an example of each: Energy form
Example
Question 2 (Energy transfers) Give an example of each of the following energy transfers: Mechanical energy to heat energy: ______________________________________________________________________________ ______________________________________________________________________________ Gravitational potential energy to kinetic energy: ______________________________________________________________________________ ______________________________________________________________________________ Electrical energy to sound energy: ______________________________________________________________________________ ______________________________________________________________________________ Chemical energy to kinetic energy: ______________________________________________________________________________ ______________________________________________________________________________ it together (Quiz) Energy • Activity 2.7 Putting
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Activity 2.7 Putting it together (Quiz)
Question 3 (Mechanical energy) A student throws a ball into the air and then catches it as it comes down. Explain how this shows that mechanical energy is conserved: ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________ Question 4 (Mass and weight) A young student in Alice Springs has a mass of 40 kg. What is her weight (using the proper scientific unit): ______________________________________________________________________________ If she were in orbit on the space station what would be her: Mass? ______________________________________________________________________________ Weight? ______________________________________________________________________________ Question 5 (Pulleys) A student designs the simplest block and tackle (pulley) system to lift a heavy rock alone. The rock has a mass of 120 kg and the student has a mass of 39 kg. The student finds that he can use his own body weight on this pulley system to lift the rock. What is the mechanical advantage of this pulley system? ______________________________________________________________________________ ______________________________________________________________________________ If he wants to lift the rock one metre, how much rope must be hauled through the pulley? ______________________________________________________________________________ ______________________________________________________________________________ Question 6 (Starting fires) Write a paragraph describing the energy transfers involved in starting a fire using the drill method. You should include the following terms: Mechanical energy Kinetic energy Heat energy Light energy Chemical energy it together (Quiz) Energy • Activity 2.7 Putting
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Activity 3.1 What is heat?
Activity 2.4 Energy in, energy out
Watch the animation. It is in three sections so you can answer the following questions:
Animation 1: Can you think of a fair test of Rumford’s idea that heat was caloric fluid? ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________
Energy • Activity 3.1 What is heat?
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Activity 3.1 What is heat?
Activity 2.4 Energy in, energy out
Animation 2: What results would you expect to see? What results would you expect if the theory of caloric fluid was correct? ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________
Energy • Activity 3.1 What is heat?
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Activity 3.1 What is heat?
Activity 2.4 Energy in, energy out
Animation 3: How did Rumford’s observations disprove the caloric theory? ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________
Energy • Activity 3.1 What is heat?
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Conclusions
Activity 3.1 What is heat?
Activity 2.4 Energy in, energy out
People had observed that the cannon barrels got very hot when they were being bored out. Cannon barrels were known to become hot when bored out. 1. What was Rumford’s hypothesis? ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________ 2. Rumford proposed a fair test. Describe it. ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________ 3. Why was it a good test of his hypothesis? ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________ 4. The results were surprising. What were the observations? ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________ 5. Did these results support or disprove Rumford’s hypothesis? ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________
Energy • Activity 3.1 What is heat?
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In this task you will design a system to heat water with sunlight. Complete the task in a small group, but write an individual report.
Activity 3.6 Solar energy
What to do: 1. Design a device to collect sunlight to heat 1.25 L of water. Your basic equipment includes:
a cardboard box a PET bottle to hold 1.25 L aluminium foil cling wrap. cold tap water (1.25 L) thermometer.
You may use other equipment as needed. You may need to test your design, measure results and adjust as needed. 2. Write your report with the following headings:
Aim: One or two sentences stating clearly what the investigation was designed to achieve. Materials: List equipment used. Risk assessment: Identify and assess any risks and list precautions taken. Your teacher will discuss this with you before you start. Method: Record all steps and procedures used. You should clearly describe your heater design. A diagram would be useful. You should then describe how you evaluated your design. What measurements did you take? Use full sentences (this is called prose) in past tense, as you are describing what you did. Results: Record your observations and measurements showing how well your design worked. A table of results might be easiest. You could use a histogram to show the heating effect. Discussion: You should explain: the scientific reasons behind your design how you evaluated whether it worked what improvements you made or those that could be made. Conclusion: Summarise in one or two sentences how you achieved the best effect.
Energy • Activity 3.6 Solar energy
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Marking Scheme: Report on water heater design
Activity 3.6 Solar energy
Name: ……………………………………………………………………………….. Area of assessment Heater design
Written report
Problem solving
Outcomes
Marks
Did the group go through an appropriate design and appraisal cycle?
0
1 2
Could the group describe why they were using particular designs using appropriate scientific language?
0
1 2
Is the aim stated clearly?
Is the list of materials complete?
0
1 2
Is there a suitable risk assessment?
0
1 2
Does the method describe the design and appraisal methods clearly?
0
1 2
Is the data presented clearly?
0
1 2
Does the conclusion concisely reflect the aim?
0
1 2
Overall, is the writing clear and concise?
0
1 2 3
Does the discussion in the report draw on scientific understanding?
0
1 2 3
Was there a logical and clear progression through the appraisal and development of the heater?
0
1 2
Are there suggestions for future design improvements?
0
1 2
0
Total Mark
Energy • Activity 3.6 Solar energy
1
/25
2
