Test Review: Machines and MA

Test Review: Machines and MA

by William Lovering

Multiple Select

How does using a simple machine affect work? Mark all the answers that are correct (may be more than one).

• it decreases the amount of work you have to do

• it can change the amount of force needed to do the work

• it can change the direction of force when doing work

• it reduces the amount of energy required to do work

Multiple Choice

Wheezy uses a ramp with a MA of 3 to do 600j of work on a box. How much work did the ramp do?

• 200j

• 1800j

• 600j

• None of these

Multiple Choice

If Lorenza uses a compound pulley to increase his force when lifting a heavy object, what also must be true?

• The distance the object moves will be less than his input

• The distance the object moves will be more than his input

• The amount of work he does will decrease

• The power he uses will increase.

Multiple Choice

Which of the following is NOT using a simple machine?

• An athlete climbing a rope.

• A student walking up stairs.

• A chef carving a turkey with a knife.

• A baseball player swinging a bat.

Multiple Choice

Mesha uses a bottle opener as a lever to open a soda. She applied 20n of force to open a bottle that normally requires 60n to open. What is the mechanical advantage of the bottle opener?

• 3

• 0.33

• 1200

• none of the above

Multiple Choice

Ja'Quan knows that wedge always increases the input force. Which of the following could be the MA of a wedge?

• 2

• 1

• 0.5

• -1

Multiple Choice

Every type of simple machine has its own equation to calculate MA. What is the standard equation to calculate mechanical advantage?

• $$MA=F_{in}\cdot F_{out}$$

• $$MA=\frac{F_{in}}{F_{out}}$$

• $$MA=\frac{F_{out}}{F_{in}}$$

Multiple Choice

What type of lever is a nutcracker (like the one pictured)?

• 1st class

• 2nd class

• 3rd class

Multiple Choice

What is a lever?

• •a moveable bar that cannot move around a fixed point, called a fulcrum.
• •a rigid bar that is free to move around a fixed point, called a fulcrum.
• •a moveable bar that is free to move around a fixed point, called a fulcrum
• •a rigid bar that cannot move around a fixed point, called a fulcrum

Multiple Choice

What class of lever is this?

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

Multiple Choice

Which type of lever is this?

• First Class Lever
• Second Class Lever
• Third Class Lever
• Coach  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 class lever is a nutcracker?

• 1st

• 2nd

• 3rd

Multiple Choice

What class lever is a fishing rod?

• 1st

• 2nd

• 3rd

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

Using a lever, Joe is able to lift a 10,000 N car off of the ground with a force of 1000 N. What is the mechanical advantage of the lever (MA=Output Force/Input Force)?

• 1

• 10

• 100

• 1000

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

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

What class lever does this picture show?

• 1st

• 2nd

• 3rd

Multiple Choice

What class lever does this picture show?

• 1st

• 2nd

• 3rd

Multiple Choice

Which lever has the largest MA?

• A

• B

• C

Multiple Choice

Which lever would be the easiest to lift the load?

• C

• A

• B

Multiple Choice

Which lever has an MA of less than one?

• A

• B

• C

Multiple Choice

Which lever would be the easiest to lift the load?

• A

• B

• C

Multiple Choice

A wheel is...

• A circular disc that can turn or roll

• Any shape that can turn, like a triangle

• A flat shape that hovers

• A small, rigid rod that can turn

Multiple Select

Which of these are examples of wheels and axles? Tick all the correct answers

• Doorknob

• Ramp

• Gears

• Steering wheel

Multiple Choice

A large wheel takes less force to turn than a small wheel

• True

• False

Multiple Choice

If you apply force to the wheel in a wheel and axle, the force on the axle will be...

• greater

• less

• equal

Multiple Choice

How much force would be required to lift a 200n object with a simple, fixed pulley?

• 200n

• 100n

• 400n

• not enough information

Multiple Choice

What is the mechanical advantage of this pulley?

• 1

• 2

• 3

• 4

Multiple Choice

Out of these which one is an inclined plane, that can make work most easier?

• 1
• 2
• both
• none

Multiple Choice

What is the mechanical advantage of an inclined plane which has 4 cm height and 16 cm slope?

• 1/4
• 1
• 16
• 4

Multiple Choice

Whats an inclined plane?

• a sloping ramp up which heavy loads can be raised
• a round machine used for traveling
• a ramp that launches planes

Multiple Choice

When an object is moved up a ramp, you need _________ effort than if it is just picked straight up. 

• More
• Less
• same

Multiple Choice

The purpose of a simple machine is to reduce the amount of _____ needed to accomplish a task.

• force

• work

• mechanical advantage

• efficiency

Multiple Choice

A wedge always...

• decreases your

• increases the input force

• has a MA of 1

• decreases the work

Multiple Choice

If Javious is pushing down on a knife to slice an orange, which direction is theforce from the knife to the orange?

• down also.

• out to the sides

• up

• there is no force on the orange

Multiple Choice

An inclined plane wrapped around a rod forms this simple machine 

• lever
• pulley
• screw
• wedge 

Multiple Choice

What type of simple machine is found on the cap of a jar?

• Screw

• Pulley

• Lever

• Inclined Plane

Multiple Choice

Kylie is helping design some furniture for IKEA. People will need to assemble it themselves so she wants it to be easy. Her designers bring 3 types of screws to hold it together. They are all the same length and diameter. Which of the following would require the least force for customers to use.

• Screw A with 300 threads

• Screw B with 600 threads

• Screw C with 900 threads

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)

Some text here about the topic of discussion

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

Mechanical advantage is the number of times a machine _____ the effort.

• multiplies

• reduces

• redirects

Multiple Choice

Using an inclined plane to move a piano into a truck:

• does not reduce the amount of work, but does make the work easier by using less force to move the piano.

• does not reduce the amount of force, but does make the work easier to move the piano.

• does reduce the amount of work and makes the work easier by using less force to move the piano.

• increases the amount of work by using more force to move the piano.

Fill in the Blank

What is the MA of an inclined plane with a length of 30cm and a height of 14 cm? Use a calculator to help you find the answer. Round to the nearest whole number.

Multiple Choice

If the weight of the block is 10N, how much force does one have to apply to lift it using this pulley (MA=2)?

• 2N
• 5N
• 10N
• 15N

Multiple Choice

A machine with a ratio less 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.

Multiple Choice

if a load of a lever is 100 newtons and the force you apply is 20 newtons, what is your mechanical advantage?

• 120 N
• 5 N
• 2000 N
• 80 N

Multiple Choice

What is the mechanical advantage if you lift a load of 300 newtons and you only push down with 50 newtons?

• 250
• 50
• 60
• 6

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.

Fill in the Blank

What is the MA of an inclined plane with a length of 40 cm and a height of 14 cm Use a calculator to help you find the answer. Round to the nearest whole number.

Multiple Choice

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

• Yes

• No

Fill in the Blank

As a percent, what is the efficiency of a machine that puts out 90 J of work when you put in 100 J of work?

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

What is the efficiency of a machine if 55.3 J of work are done on the machine, but only 14.3 J is produced by the 1machine?

• 0.25 J
• 26%
• 386%
• 3.86 J

Multiple Choice

Which of the following would be a frictionless machine?

• ideal

• lever

• wheel and axle

• pulley

• wedge

Multiple Choice

What does friction produce that reduces efficiency?

• heat

• water

• energy

• work

Multiple Choice

In real simple machines, work input is work:

• done on the machine

• done by the machine

• that is 100% efficient

• that is over 100% efficient

Multiple Choice

Real machines:

• actually exist

• have an efficiency less than 100%

• lose energy due to friction

• all are correct

Multiple Choice

A simple machine reduces the amount of work needed to accomplish a task.

• true

• false