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Levers and Pulleys
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Levers and Pulleys. Levers A lever is a tool that people use to make work easier. Levers are used to lift things or overcome resistance. Levers give us.

Dec 27, 2015

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Randolph Logan
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Page 1: Levers and Pulleys. Levers A lever is a tool that people use to make work easier. Levers are used to lift things or overcome resistance. Levers give us.

Levers and Pulleys

Page 2: Levers and Pulleys. Levers A lever is a tool that people use to make work easier. Levers are used to lift things or overcome resistance. Levers give us.

Levers

• A lever is a tool that people use to make work easier.

• Levers are used to lift things or overcome resistance.

• Levers give us an advantage by making work easier.

Page 3: Levers and Pulleys. Levers A lever is a tool that people use to make work easier. Levers are used to lift things or overcome resistance. Levers give us.

Vocabulary

• The lever arm is a stick or beam, that can pivot or turn at a point.

• The fulcrum is the point around which the lever arm pivots or turns

• The mass lifted by the lever is the load. • The effort is the force (push or pull) needed to

lift or pull the load

Page 4: Levers and Pulleys. Levers A lever is a tool that people use to make work easier. Levers are used to lift things or overcome resistance. Levers give us.

Challenge:

• Set the load at 15 cm. • Can you lift load using 1 finger? • Does it always take same effort to lift load?• Where should you press to lift load with least effort?• • Discuss in groups: What advantage can be gained by

using the lever to lift the load?• How can you measure advantage provided by the

lever?

Page 5: Levers and Pulleys. Levers A lever is a tool that people use to make work easier. Levers are used to lift things or overcome resistance. Levers give us.

Practice reading spring scale

• Spring scales measure the effort needed to lift the load

• Effort is a force. Force is measured in Newtons.

• Use the scale right side up. Hang it, and pull down on bottom hook. The amount of force is read directly from the scale.

• Spring scale

Page 6: Levers and Pulleys. Levers A lever is a tool that people use to make work easier. Levers are used to lift things or overcome resistance. Levers give us.

Rules for using scales:

• Always be sure the scale reads zero.• Use it right side up, not upside down.• Pull until the lever arm is level, then read the scale in

Newtons. • Stop before the scale goes past 10 N.• Additional rules – scale readings are made from the

top of the metal bar• Each little line represents .2 N. When indicator is

between 2 lines, students should estimate to nearest .1 N.

Page 7: Levers and Pulleys. Levers A lever is a tool that people use to make work easier. Levers are used to lift things or overcome resistance. Levers give us.
Page 8: Levers and Pulleys. Levers A lever is a tool that people use to make work easier. Levers are used to lift things or overcome resistance. Levers give us.

How much force is necessary to lift load?

• A scale is helpful to determine how much force is necessary. Force is measured in Newtons

• Today, the load stays at 10cm. • Effort is applied at different distances from the

fulcrum. • Record the scale reading on the left side of the

effort column.

Page 9: Levers and Pulleys. Levers A lever is a tool that people use to make work easier. Levers are used to lift things or overcome resistance. Levers give us.

Lever Experiment A

Demonstrate the force of the scale: Put load 5 cm from fulcrum.

Put scale 25 cm on other side.

Pull down to balance.

Read scale. How can this be?

Page 10: Levers and Pulleys. Levers A lever is a tool that people use to make work easier. Levers are used to lift things or overcome resistance. Levers give us.

Lever Experiment B

• Using the graphs for both Lever Experiment A and Lever Experiment B, answer this question.

• Where should you put the load, and where should you put the effort, for the greatest advantage? Where is it easiest to lift the load?

Page 11: Levers and Pulleys. Levers A lever is a tool that people use to make work easier. Levers are used to lift things or overcome resistance. Levers give us.

Lever Classes

• Does the fulcrum always have to be in between the load and the effort?

• If the fulcrum is not in the middle, is it still a lever? Is there an advantage to moving the fulcrum to a different position on the lever arm?

Page 12: Levers and Pulleys. Levers A lever is a tool that people use to make work easier. Levers are used to lift things or overcome resistance. Levers give us.
Page 13: Levers and Pulleys. Levers A lever is a tool that people use to make work easier. Levers are used to lift things or overcome resistance. Levers give us.
Page 14: Levers and Pulleys. Levers A lever is a tool that people use to make work easier. Levers are used to lift things or overcome resistance. Levers give us.
Page 15: Levers and Pulleys. Levers A lever is a tool that people use to make work easier. Levers are used to lift things or overcome resistance. Levers give us.

Lever ClassIt’s as easy as:1 2 3F L E The number stands for the class. The letter stands for what’s in the middle.

ABC Baby you and me!

Page 16: Levers and Pulleys. Levers A lever is a tool that people use to make work easier. Levers are used to lift things or overcome resistance. Levers give us.

Remember123 FLE

Label each drawing and then identify the lever class

Page 17: Levers and Pulleys. Levers A lever is a tool that people use to make work easier. Levers are used to lift things or overcome resistance. Levers give us.

Real Life Levers

• Go back to the first slide and label the fulcrum, the load, and the effort. Then identify the class of lever.

Page 18: Levers and Pulleys. Levers A lever is a tool that people use to make work easier. Levers are used to lift things or overcome resistance. Levers give us.

Pulleys

• A wheel with a grooved rim in which rope can run to change the direction of the pull that lifts the load.

• Task: How can a pulley be used to lift a load?

Page 19: Levers and Pulleys. Levers A lever is a tool that people use to make work easier. Levers are used to lift things or overcome resistance. Levers give us.
Page 20: Levers and Pulleys. Levers A lever is a tool that people use to make work easier. Levers are used to lift things or overcome resistance. Levers give us.
Page 21: Levers and Pulleys. Levers A lever is a tool that people use to make work easier. Levers are used to lift things or overcome resistance. Levers give us.

Pulley’s Advantage

Pulleys can give two kinds of advantage: • Reduced effort is called mechanical

advantage• Pulleys can also change the direction that the

effort is applied. That is called directional advantage.

Page 22: Levers and Pulleys. Levers A lever is a tool that people use to make work easier. Levers are used to lift things or overcome resistance. Levers give us.

Pulleys Lesson 2

• How are fixed and movable pulleys the same? • What kind of advantage is produced by each

system?• In what way are levers and pulleys the same?

• Is there any advantage to using two pulleys at the same time?

Page 23: Levers and Pulleys. Levers A lever is a tool that people use to make work easier. Levers are used to lift things or overcome resistance. Levers give us.

Drawing Pulley Diagrams

• Draw an anchor point at top• Draw large dot to show where rope attaches. • Draw lines to show how rope goes around

pulley• Draw load and effort using same symbols and

letters

Page 24: Levers and Pulleys. Levers A lever is a tool that people use to make work easier. Levers are used to lift things or overcome resistance. Levers give us.
Page 25: Levers and Pulleys. Levers A lever is a tool that people use to make work easier. Levers are used to lift things or overcome resistance. Levers give us.
Page 26: Levers and Pulleys. Levers A lever is a tool that people use to make work easier. Levers are used to lift things or overcome resistance. Levers give us.