Lesson: Simple Machines and MA

Lesson: Simple Machines and MA

By William Lovering

Simple Machines

Learning Targets:
• I can calculate the work and mechanical advantage for simple machines. (Reasoning) 

• I can analyze a model of a simple machine to calculate the mechanical advantage. (Reasoning) 

• I can infer which machines would be better suited for specific tasks based on their mechanical advantage. (Reasoning)

In science this term means a force that is applied through a distance.

• what is important here is that for work to be done on an object, it has to move.​​​

What is work?

No for work to be done the object has to move. You can't move a door that says PULL if you push on it.

Answer

a machine is a device that can make work easier by changing the force or motion of an object.

• example:

  • lifting a piano

    • for many people, without the help of some type of pulley system or a ramp.

What's a machine?

• When you use a machine, you apply force to the machine.

  • This force is called the input force.

• The machine then applies force to an object.

  • This force is called the output force.

• The output force may or may not be the same as the input force.

What Else...

• The force that you apply to the machine is applied over a given distance, called the input distance.

• The force applied by the machine to the object is also applied over a distance, called the output distance.

• The output distance may or may not be the

  same as the input distance.

And...

• the machines do NOT increase the AMOUNT OF WORK that you are doing on the object. They ONLY change how the work is done.

  • ​they make it easier to do work by:

    • increasing the force

    • increasing the distance

    • changing the direction

warning!!!

​

1. Simple machines

   1. these are machines that do work with only one movement of the machine

2. Compound machines

   1. these are combinations of 2 or more simple machines​

Types of machines

​

Multiple Choice

A simple machine is a device that helps to reduce the amount of _____ required to work.

• force
• energy
• work

Inclined Plane

An inclined plane is a plane tilted at an angle, with one end higher than the other.

Wedge

A wedge is an inclined plane or two inclined planes that meet each other to form a sharp edge.

Pulley

A pulley is a grooved wheel that turns around and axle which is held in place by mounting bracket.

Fixed Pulley

has the axle fixed on a surface and therefore does not move. Its fulcrum is at the center of the axle with load and effort on either side. It does not increase the magnitude, speed, or distance of the force. Fixed pulleys are used in flagpoles and clotheslines.

Movable Pulley

moves along the rope or wire. The fulcrum is at the edge of the wheel with the load at the middle of the axle and the effort at one end of the rope. It increases the magnitude of the force but decreases its distance. Esamples of movable pulleys are ziplines, weight machines, and elevator cables.

Compound Pulley

is made up of a combination of two or more fixed and movable pulleys. Compound pulleys are used in ships and billboards.

Screw

A screw is actually a spiral inclined plane. It is composed of a cylindrical body with a spiral ridge called thread. The treads surround the cylinder from the tip to the head. A screw increases the force but a longer distance.

Wheel and Axle

The wheel and axle is a machine that has a small disk or shaft called an axle that is attached to a wheel.

Lever

A lever is a straight or curved rigid bar that is free to turn about a fixed point.

All levers have three location of interest:

• Fulcrum or Fixed Point

• Point of Effort where work is done on the lever

• Load which is being moved

Multiple Choice

Identify this Simple Machine.

• wedge
• pulley
• inclined plane
• wheel and axle

Multiple Choice

Identify this Simple Machine.

• Wheel and Axle
• Lever
• Pulley
• Wedge

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

• Fulcrum
• Effort
• Load
• None of these

Multiple Choice

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

Multiple Choice

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

Multiple Select

How can machines help you do work? (Select all that apply)

• Change the amount of force you're using

• Change the amount of work you're doing

• Change the direction of your force

• Change the distance you move something

Multiple Choice

What is effort (input) force?

• the force one exerts on a machine

• the force which an effort force must overcome in order to do work on an object via a simple machine.

• the force the machine exerts on a object

• the output work times the input distance

Multiple Choice

The ramp helps the man do work by reducing the input ____________.

• distance
• force
• time
• power

Multiple Choice

What class of lever is this?

• 1st class
• 2nd class
• 3rd class
• None of the above

Multiple Select

How can a class 1 lever affect your force? (Select all that apply)

• increases

• decreases

• changes direction

• No effect

Multiple Select

How can a class 2 lever affect your force? (Select all that apply)

• increases

• decreases

• changes direction

• No effect

Multiple Select

How can a class 3 lever affect your force? (Select all that apply)

• increases

• decreases

• changes direction

• No effect

Multiple Select

How does a wedge affect your force? (Select all that apply)

• increases

• decreases

• changes direction

• no effect

Multiple Choice

How do you use a wheel and axle to increase your force?

• Apply force to the wheel so it turns the axle

• Apply force to the axle so it turns the wheel

• A wheel and axle always decreases force

• Rotate it counter-clockwise

Multiple Choice

How do you use a wheel and axle to decrease your force?

• Apply force to the wheel so it turns the axle

• Apply force to the axle so it turns the wheel

• A wheel and axle always decreases force

• Rotate it counter-clockwise

Multiple Choice

Which mechanical advantage would increase your force?

• 1

• 2

• 0.5

• All of the above

Multiple Choice

Which mechanical advantage would decrease your force?

• 1

• 2

• 0.5

• All of the above

Multiple Choice

Which mechanical advantage would keep your force the same?

• 1

• 2

• 0.5

• All of the above

Multiple Choice

A lever has a load arm of 1 meters and a mechanical advantage of 6. What is the size of the effort arm.

• 2

• 4

• 6

• 8

Multiple Choice

A lever has a load arm of 3 meters and a mechanical advantage of 4. What is the size of the effort arm.

• 0.75

• 1.3

• 7

• 12

Multiple Choice

What is the mechanical advantage in the picture?

• 2

• 1

• 0.5

• 3

Multiple Choice

A ramp has a mechanical advantage of 4. If it is 15 feet long, how high is it?

• 3.75 ft

• 60 ft

• 11 ft

• not enough information to solve

Multiple Choice

If a student uses 10 Newtons of Force to push a chair 5 meters, how much is work is being done?

• 2 Joules
• .5 Joules
• 50 Joules
• 20 Newtons

Multiple Choice

What is mechanical advantage?

• The advantage a machine has over a bicycle

• A measure of how much a simple machine reduces work

• A measure of when is the best time to use a simple machine

• the number of times a machine increases input force

Multiple Choice

What is resistance (output) force?

• the force required by a machine in order to accomplish work (the force you put on the machine)

• The force that is exerted by a machine

• the force the machine exerts on a object

• the output work times the input distance

Multiple Choice

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

Multiple Choice

Is it possible to have a machine in the real world with 110% efficiency?

• Yes

• No

Multiple Choice

Which of the following machines loses the most energy to heat?

• 50% efficient machine

• Output Work = 60 J

  Input Work = 100 J

Multiple Choice

You push down on a lever with a force of 100 N to lift a 500 N box.

What is the input force?

• 100 N

• 500 N

Multiple Choice

In a real-world machine, what is true about work in compared to work out?

• Work In > Work Out

• Work In = Work Out

• Work In < Work Out

Multiple Choice

No machine in existence has 100% efficiency due to ____________________.

• magic
• friction
• smoke
• input

Multiple Choice

A simple machine has an input force of 12 N and an output force of 4 N. What is its mechanical advantage?

• .33

• 3

• 8

• 16