The wire cutters in Figure 9. The equations show how a simple machine can output the same amount of work while reducing the amount of effort force by increasing the distance over which the effort force is applied. Work power and machines worksheet. In real life, some of the applied work always ends up as wasted heat due to friction between moving parts. Recall that in closed systems the total amount of energy is conserved. Combining this with the information in the paragraphs above, we can write. BL] [OL] Ask the students what they know about machines and work. A simple machine is a mechanical device used to apply increased force.
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Work And Machines Worksheet Pdf English
AL]Tell students there are two other classes of levers with different arrangements of load, fulcrum, and effort. A complex machine is a combination of two or more simple machines. Reduce the radius of the pulley. There are six simple machines: lever, inclined plane, wedge, pulley, wheel and axle, and screw. Work and machines worksheet pdf worksheet. Calculating Mechanical Advantage and Efficiency of Simple Machines. Ask them first to try to sketch these. The screw shown in Figure 9.
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It is actually a form of lever. The input force of 11 N acting on the effort arm of a lever moves 0. Ask them why steering wheels had a greater diameter before power steering was invented. Don't let them confuse the term with complicated machines such as computers.
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Give some examples: hand-powered windlass, steering wheel, door knob, and so on. 4 ropes are required because the actual mechanical advantage is 3. Efficiency is related to friction, and friction depends on the smoothness of surfaces and on the area of the surfaces in contact. The equation for IMA is shown in Figure 9. Since both have different weights, they will never be in balance. True or falseāThe efficiency of a simple machine is always less than 100 percent because some small fraction of the input work is always converted to heat energy due to friction. Refer back to the discussions of each simple machine for the specific equations for the IMA for each type of machine. Work and machines worksheet pdf english. Increase the number of pulleys. Some levers exert a large force to a short effort arm. After they have discovered the three kinds, with or without your help, ask if they can think of examples of the types not shown in Figure 9.
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The simple machine shown in Figure 9. AL] Ask for recall of the formula W = f d. Explain that the product of force and distance is critical to understanding simple machines. The down side is that you must exert the force over a greater distance, because the product of force and distance, f d, (which equals work) does not change. Pulleys can still be seen in use, most commonly on large building cranes.
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For a screw, the input distance is the circumference of the circle over which the force is applied, and the output distance is the distance between the screw threads. Simple machine||wedge||wheel and axle|. Increase the number of ropes supporting the load. Explain why more energy is usually lost to friction with these machines than with other simple machines. Watch children in 4th grade and 5th grade flit between the simplicity and complexity of machines. For a pulley system, the input distance is how far you pull the rope, and the output distance is the distance the load rises. NGSS: 3-5-ETS1-1, 3-5-ETS1-2, 3-5-ETS1-3, 3-PS2-1, 3-PS2-2. State the equation for efficiency of a simple machine, and calculate Wo and Wi. Look back at the pictures of the simple machines and think about which would have the highest efficiency.
Work Power And Machines Worksheet
Remind the students that, for an ideal machine, work in = work out and that W = f d. The video shows how to find the fs and the ds. BL] [OL] Review the material on loss of mechanical energy to heat and the law of conservation of energy. For an additional fun activity, have the students search the Internet for Rube Goldberg machine. Explain that simple machines are often hand-held, and that they reduce force, not work. An answer key is included for each worksheet. When you go down a slide at a park, the simple machine whose industry you owe a debt of gratitude to is an inclined plane. Note that, when using an inclined plane the load moves, but when using a wedge the load is stationary and the machine moves. BL] [OL] The calculation for IMA of a pulley seems too easy to be true, but it is. 10 shows the simple formulas for calculating the IMAs of these machines. Our worksheets on the simple machines are ideal for grade 3, grade 4, and grade 5. Pulleys were once seen on sailing ships and farms, where they were used lift heavy loads.
Sort the machines into one of the 6 types. Ask for an explanation of the 2 in the equation for IMA.