Work, Power, Efficiency, Simple Machines, & MA

Efficiency is a measure of how much of the work put into a machine is converted into useful output work. Why can efficiency never reach 100%?

• acceleration

• elasticity

• friction

• gravity

Tags

NGSS.MS-PS3-3

NGSS.MS-PS3-5

 An inclined plane wrapped around a rod forms this simple machine 

• lever

• pulley

• wedge

• screw

Calculate the amount of work done if you use a 100N force to push a 50kg box 5m across the kitchen floor.

• 250 J

• 500 J

• 5000 J

• 50,000J

Tags

NGSS.HS-PS2-1

If a machine exerts a force of 250 N on an object and no work is done, what must have occurred?

• The machine has broken

• The object has not moved

• The object has gained momentum.

• The object has moved, but then stopped

Tags

NGSS.HS-PS2-1

A man has an air conditioner he wants to load into the back of his truck. Instead of lifting the air conditioner and carrying it to the truck, he improvises a ramp. He takes a board that is 3.6 meters long and places one end of it in the back of his truck, 1.2 meters off the ground. He leaves the other end of the board on the ground. He places the air conditioner on a dolly and pushes them both up the ramp and into the truck. What is the mechanical advantage of the ramp?

• 3.0

• 2.5

• 4.32

• 4.8

Tags

NGSS.MS-ETS1-1

What is evidence that work is being done?

• A machine is used.

• The man exerts a force.

• A simple machine makes work easier.

• The man exerts a force and moves the load.

What is the mechanical advantage of the block and tackle used to lift the bale of cotton?

• 1

• 2

• 3

• 4

Where should the fulcrum be located in this lever to get the greatest mechanical advantage?

• at position I, because the length of the effort arm should be greater than the length of the load arm

• at position II, because the effort arm and the load arm should have equal lengths

• at position III, because the length of the load arm should be greater than the length of the effort arm

• at position IV, because the effort should be applied as close to the fulcrum as possible

Tags

NGSS.MS-ETS1-2

What simple machines are used to create the shovel?

• Wheel and axle

• Wedge and inclined plane

• Screw and inclined plane

• Lever and wedge

Tags

NGSS.MS-PS2-1

Which two simple machines are found in a pair of scissor?

• screw and lever

• lever and wedge

• screw and inclined plane

• pulley and ramp