Mechanical Advantage and Simple Machines

Mechanical advantage of simple Machines

By Ms. Taylor

Simple Machines

What are they?

A device that makes work easier by changing the size or direction of a force.

Work input- work done by you on the machine.

Work output- work done by the machine on an object​.

They make work easier by increasing the work output and decreasing the work input​.

Mechanical Advantage

What is it?

• The more help from the machine the easier the task is.

• The more force made by the machine…the easier it is.

• ​A machine gives mechanical advantage (MA) when it results in greater output force than input, hence, making work easier.

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Mechanical Advantage, MA

How to interpret MA

• ​A machine that gives a MA 1 only causes a change in direction.

• ​A machine that gives a MA less than 1 usually increases the distance over which the work is done.

• ​A machine that gives a MA greater than 1 usually increases the output force (less force needed)

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Multiple Choice

The amount that input is magnified by a simple machine is known as the :

• mechanical advantage

• output force

• resistance

• none of these

Multiple Choice

If we get a mechanical advantage of 1 from using a simple machine , we will have to "pay for it" with the cost of more _____________ .

• force

• distance

• mechanical advantage

• effort

Multiple Choice

Mechanical advantage is a measure of how much a machine multiplies the input

• efficiency.
• force.
• power.
• work.

Wedges

Screw

Inclined plane​

Types of Simple Machines

Lever

Wheel and axle

Pulleys​

• Straight, slanted surface

• Does not decrease amount of work needed but increases the distance.

• Same work is done but over a

greater distance.​

• longer ramp, more MA

• MA=length/height of ramp​

Inclined plane

Wedge

• A pair of incline planes that move together to pull things apart.

  ​

• MA= the longer and thinner the wedge is the more mechanical advantage it has.

Screw

• Inclined plane wrapped around a cylinder

• ​Longer the spiral and the closer the threads are together the greater mechanical advantage.

Multiple Choice

How can you decrease the effort force needed to push a weight to the top of the ramp? 

• cover the surface with carpet
• increase the length of the ramp
• increase the height of the ramp
• decrease the length of the ramp

Multiple Choice

What is the primary mechanical advantage of using the simple machine seen in the image?

• You can apply a large force and have it penetrate over a very long distance.
• You can apply a long distance and have it convert into a very short distance.
• You can apply a short distance and have it multiplied to penetrate a large distance.
• You can apply a small force to penetrate something that normally requires a large force.

Multiple Choice

To increase the mechanical advantage of a lever

• make sure the fulcrum is in the middle of the lever
• move the fulcrum closer to the load
• move the fulcrum closer to the effort
• use a bigger fulcrum

Multiple Choice

A simple machine that splits an object apart is a

• inclined plane
• fulcrum
• wedge
• lever

Wheel and axle

• Two circular object of different sizes working together

  ​

• Larger the wheel the greater the MA​ (more distance). It multiplies the input force.

  ​

• MA= radius of the wheel

radius of the axle​

Classes of Lever:

• It has a bar that pivots at a fixed point.

• The fixed point is a FULCRUM.

• The applied force is the EFFORT.

• The LOAD is what is being moved.​

What are they?

Levers

Levers

Mechanical Advantage

of levers

• Generally, the closer the fulcrum is to the load, or the greater the distance between the effort and fulcrum, the less input force needed.

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Pulleys

What is it?

• Has a grooved wheel that holds a rope or cable.

• One end has the load attached.

• The other end is where the input force is applied.

• May be fixed or movable.​

• Attached to the object being moved!

• ​MA depends on the number of supporting rope segments.

• More movable pulley, reduces the force needed by that amount​.

Movable Pulleys

• DOES NOT MOVE.

• One end of rope is connected to the load and the other end is pulled.

• Makes work easier by changing force direction​

Fixed Pulleys

Pulleys

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Count number of supporting ropes then divide the weight of load by that amount to get effort (input) force needed.

​

​Mass=10N,

MA=2

Input force =10/2=5N​

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​MA of movable Pulleys

​

Multiple Choice

This 2000 N weight is raised 1 meter by pulling 4 meters of rope. What force was required to pull the rope?

• 500 N
• 1000 N
• 2000 N
• 8000 N

Multiple Choice

If a pulley system has a mechanical advantage of 4, what does that mean?

• This means that it is 4 times easier to lift this load.

• This means you only need a quarter of the effort to lift the load.

• For example, if you lifted 100 kg, it would only take 25 kg of effort.

• All of the above

Multiple Choice

A simple machine usually used to raise a flag is a (an)

• inclined plane

• pulley

• lever

• wheel and axle

Multiple Choice

A machine with a ratio greater than 1:

• multiplies the input force so the machine would be good to help move heavy objects.

• does not multiply the force, but increases distance and speed.

• is good for lifting and moving objects quicker.

• Is not good for lifting or moving objects quicker.