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Simple Machines

Simple Machines. How do they relate to work and energy?. Do Now (2 minutes) . Place your bags at a desk. Form groups of 3 at a lab station. How much force is required to lift a 1kg object at a constant speed? How much work is done by a machine that lifts a 1kg mass to a height of 10 cm?.

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Simple Machines

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  1. Simple Machines How do they relate to work and energy?

  2. Do Now (2 minutes) • Place your bags at a desk. Form groups of 3 at a lab station. • How much force is required to lift a 1kg object at a constant speed? • How much work is done by a machine that lifts a 1kg mass to a height of 10 cm?

  3. Today’s Schedule • By the end of the day you should be able to: • Identify 3 ways simple machines simplify a task • Calculate the mechanical advantage of simple machines • Understand why the work performed by a machine cannot exceed the energy input • Schedule: • Complete the Simple Machines investigation • Share and Discuss our results • Complete Exit-Ticket • HW Assignment: (p.290-291) 79, 80, 81, 82

  4. Directions • Each group will investigate two simple machines: • Complete steps 1-4 or Machine #1 • (8 minutes) • When signaled, move to the next station and repeat steps 1-4 for Machine #2 • (8 minutes) • Move to a desk and complete questions 1-3

  5. Six Simple machines

  6. Machines • Mechanical Advantage is the ratio of the resistance force to the effort force • Resistance Force: Force exerted by the machine • Ex: The lever on the object • Effort Force: force exerted by you • Ex: You on the the lever.

  7. Simple machines can: • Change the magnitude of a force required to do work. • Change the direction of the force to suit the user’s needs. • Change the speed in which work is done. Simple machines cannot: Reduce the amount of work required to complete a task.

  8. The law of conservation of energy applies • to all machines! • At the same time we do work on one end of the • lever, the other end does work on the load.

  9. EFficiency • Efficiency: the ratio of the output work to the input work • Win = Findin=(5.5 N)(20 cm) • Wout= Foutdout = (10 N)(10 cm)

  10. Today’s Schedule • By the end of the day you should be able to: • Identify 3 ways simple machines simplify a task • Calculate the mechanical advantage and efficiencies of simple machines • Understand why the work performed by a machine cannot exceed the energy input • Schedule: • Complete the Simple Machines investigation • Share and Discuss our results • Complete Exit-Ticket • HW Assignment: (p.290-291) 79, 80, 81, 82

  11. Exit ticket • Identify 3 ways machines make it easier to perform a task. Don’t forget HW! : (p.290-291) 79, 80, 81, 82 • Placet ticket and classwork in the basket by the door.

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