Venhaus: Mechanical Adavantage and Efficiency

Why is a can opener considered a machine?

• It's mechanical advantage number is less than 1.

• It makes the work of removing a lid from a can easier.

• It decreases the amount of work required to remove a lid from a metal can.

• It is not a machine.

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NGSS.MS-PS2-2

NGSS.MS-PS3-5

A pulley has a mechanical advantage equal to 1 because.....

• The output force is larger than the input force.

• The output force is smaller than the input force.

• The output and input force are equal, but the direction of the force changes.

• None of the above.

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NGSS.MS-ETS1-2

A machine's _______________ is determined by comparing the input and output forces.

• efficiency

• mechanical advantage

• work

• friction

The _________ of a machine is always less than 100%.

• mechanical advantage

• friction

• force

• efficiency

Tags

NGSS.MS-PS3-5

How does using a jack to lift a car make work easier?

• it changes the size of the foce

• it changes the distance the force acts

• it changes the direction a force acts

• none of the above

How does using a hockey stick to hit a puck make doing work easier?

• it changes the size of the force

• it changes the distance the force acts

• it changes the direction the force acts

• none of the above

A pulley system uses a 250 N force to life a 2750 N crate. What is the mechanical advantage of the system?

• 11

• .09

• 687,500

• 1,100

An assembly line machine needs 150 J of input work to do 90 J of output work. What is the efficiency of the machine?

• 167%

• .6%

• 60%

• 1.67%

Why can mechanical efficiency never be 100%?

• No machine is strong enough.

• Machines are too big to allow for 100% efficiency.

• It can be 100%.

• Some energy is lost in the form of heat/sound due to friction.

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NGSS.MS-PS3-3

NGSS.MS-PS3-5

What happens to the overall efficiency of a machine as I add more machines?

• For each simple machine you add, the overall efficiency increases because it gets faster.

• For each simple machine you add, the overall efficiency decreases.

• The overall efficiency is divided in half for every simple machine you add.

• There is no connection.