8.2 EFFECT OF FORCE (LEVER AND MOMENT OF FORCE)

8.2 EFFECT OF FORCE

(LEVER AND MOMENT OF FORCE)

by KASMAWATI Moe

SIMPLE MACHINES

a device that increases or changes the direction of a force

Simple Machines

• Lever

• Wheel and Axel

• Pulley System

• Inclined Plane

• Wedge

• Screw

Lifting Loads

Lifting a load, which is a weight to be carried and moved, is an example of applying force.

Mechanical Advantage

Some simple machines create a mechanical advantage to help you use less force to lift a load. A mechanical advantage is when you apply less force to lift a load than you would without the simple machine.

Levers

Levers are probably the most common simple machine.

The fulcrum is the point in which a lever rests (pivots);

The load is what you are trying to move;

Effort is the force you apply.

First Class Levers

The fulcrum is between the effort and the load.

Second Class Levers

The load is between the effort and the fulcrum.

Third Class Levers

The effort is between the fulcrum and the load.

Leavers and Loads

A lever might be able to...

decrease the effort required to move a load;

change the direction that a load moves;

increase the distance that load moves;

Increase the speed with which a load moves.

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Multiple Choice

WHAT ARE THE 3 MAIN PARTS OF A LEVER?

• FOOT, EFFORT, REPORT

• FULCRUM, STRUCTURE, EFFORT

• FULCRUM, EFFORT, LOAD

• FULCRUM, LOAD, SUPPORT

Multiple Choice

Moment is a measure of the turning effect of a force.

• True

• False

Multiple Choice

Pivot is the point about which a force is turned by an object.

• True

• False

Multiple Choice

Principle of moments states that an object is balanced when clockwise moments are equal to anticlockwise moments.

• True

• False

Multiple Choice

Moment = force / distance from pivot

• True

• False

Multiple Choice

The greater the force, the greater its turning effect.

• True

• False

Multiple Choice

The further the force is from the pivot, the greater its turning effect.

• True

• False

Multiple Choice

The bigger the moment of a force, the smaller its turning effect.

• True

• False

Multiple Choice

What is the moment acting on the left side of the pivot?

• 2 Nm

• 20 Nm

• 200 Nm

• 0.2 Nm

Multiple Choice

What is the moment acting on the right side of the pivot?

• 2 Nm

• 20 Nm

• 200 Nm

• 0.2 Nm

Multiple Choice

A force of 4 N acts on a lever 2 m from the pivot. What is the moment?

• 8 Nm

• 6 Nm

• 2 Nm

• 3 Nm

Multiple Choice

One way to increase the turning force on a spanner is to:

• Use a shorter spanner

• Use a longer pivot

• Use a longer spanner

Multiple Choice

James weighs 200 N and sits 1 m from the pivot. Jane weighs 100 N. How far from the pivot must Jane be to balance the beam?

• 0.5 m

• 1 m

• 2 m

• 4 m

Multiple Choice

A cat weighing 50 N is 1 m from the pivot. How far away does a mouse weighing 0.5 N have to be to balance the beam?

• 1 m

• 10 m

• 100 m

• 1000 m

Multiple Choice

A force exerts a moment of 2 Nm. What is the distance of the force from the pivot?

• 2 m

• 4 m

• 1 m

• 0.5 m

Multiple Choice

A force exerts a moment of 2 Nm. What is the distance of the force from the pivot?

• 1 m

• 0.5 m

• 0.2 m

• 0.25 m

Multiple Choice

Which type of lever is this?

• First Class Lever

• Second Class Lever

• Third Class Lever

Multiple Choice

For a lever to be a first class lever the fulcrum needs to be ..

• between the load and the effort
• on one side and the load and effort on the other side 
• on the same side as the load arm. 

Multiple Choice

What kind of lever is this?

• First Class Lever

• Second Class Lever

• Third Class Lever

Multiple Choice

What class lever does this picture show?

• 1st

• 2nd

• 3rd

Multiple Choice

• 1st Class
• 2nd Class
• 3rd Class
• It is not a lever

Multiple Choice

What class lever does this picture show?

• 1st

• 2nd

• 3rd

Multiple Choice

The nutcracker is the example of .......................

• First Class of lever

• Second Class of lever

• Third Class of lever

• Fourth Class of lever

Multiple Choice

When you kick a ball the fulcrum is your ..

• foot
• ball 
• leg 
• knee

Multiple Choice

If you want to decrease the effort force when using a lever, where will you move the fulcrum? 

• Closer to the object you want to move
• Farther away from the object you want to move
• You don't move the fulcrum, you move the effort force
• None of these answers 

Multiple Choice

What class lever is a seesaw?

• 1st

• 2nd

• 3rd

Multiple Choice

What class lever is a pair of scissors?

• 1st

• 2nd

• 3rd

Multiple Choice

What class lever is a wheelbarrow?

• 1st

• 2nd

• 3rd

Multiple Choice

Unit of force.

• Meter
• Centimeter
• Newton