7.P.2.4 simple machines review

How can a person decrease the effort needed to move a heavy object up a ramp?

• by increasing the height of the ramp

• by increasing the length of the ramp

• by building the ramp from sturdier materials

• by building the ramp from lightweight materials

Answer explanation

To decrease the effort needed to move a heavy object up a ramp, one should increase the length of the ramp, which reduces the steepness and makes it easier to move the object.

Tags

NGSS.MS-PS2-2

This table shows three ramps and their mechanical advantages. Each ramp is an inclined plane having the same height but different lengths. Which statement is true of these ramps?

• Ramp 1 multiplies the force more than the other ramps.

• Ramp 2 multiplies the force more than the other ramps.

• Ramp 3 multiplies the force more than the other ramps.

• The input force is the same for all three ramps.

Answer explanation

Ramp 3 multiplies the force more than the other ramps.

Tags

NGSS.MS-ETS1-1

A student is moving a wheelbarrow filled with firewood into a barn for storage. The stairs into the barn entrance are 2 meters in height. Which would give the student the best ideal mechanical advantage to move the firewood into the barn?

• building a ramp 3 meters long

• building a ramp 6 meters long

• carrying the wood up the steps into the barn

• creating a pulley system to move the wood into the barn

Answer explanation

Building a ramp 6 meters long would provide the student with the best ideal mechanical advantage to move the firewood into the barn by reducing the effort needed to lift the load to a greater distance.

Tags

NGSS.MS-ETS1-1

NGSS.MS-ETS1-2

Which action increases a machine’s efficiency?

• increasing the amount of work

• decreasing the amount of work

• increasing the amount of friction

• decreasing the amount of friction

Answer explanation

Decreasing the amount of friction increases a machine's efficiency by reducing wasted energy and allowing it to perform work more effectively.

Tags

NGSS.MS-ETS1-1

A woman wants to dig up and replant a flower. Which shovel would make the work easiest?

• Shovel A

• Shovel B

• Shovel C

• Shovel D

Answer explanation

Shovel B is the correct choice as it is likely designed for gardening tasks like digging up and replanting flowers, making the work easier.

What change can be made to a lever to make its use more efficient?

• move the fulcrum farther from the load

• move the fulcrum closer to the load

• increase the flexibility of the lever

• decrease the length of the lever

Answer explanation

Moving the fulcrum closer to the load increases the mechanical advantage of the lever, making its use more efficient.

Tags

NGSS.MS-PS2-1

Which simple machine helps raise and lower a flag on a flagpole?

• inclined plane

• wedge

• pulley

• lever

Answer explanation

A pulley is the simple machine that helps raise and lower a flag on a flagpole by reducing the amount of force needed to lift the flag.

Tags

NGSS.MS-PS2-1

Stairs are a common example of an inclined plane. How do inclined planes like stairs create a mechanical advantage?

• They reduce the amount of force needed by spreading the work over less distance.

• They reduce the amount of work needed by spreading the force over less distance.

• They reduce the amount of force needed by spreading the work over greater distance.

• They reduce the amount of work needed by spreading the force over greater distance.

Answer explanation

The correct answer is that inclined planes like stairs reduce the amount of force needed by spreading the work over greater distance.

A person could most efficiently move objects into a moving truck by using (a)   .

• by using a lever

• by using a pulley

• by using an inclined plane

• by using a wheel and axle

Answer explanation

The most efficient way to move objects into a moving truck is by using an inclined plane, as it reduces the amount of force needed to lift the objects vertically.

Tags

NGSS.MS-PS2-1

This diagram shows a can opener, a compound machine. What three simple machines does it contain?

• lever, screw, pulley

• screw, wedge, inclined plane

• wedge, lever, wheel and axle

• pulley, wedge, wheel and axle

Answer explanation

The can opener contains the simple machines wedge, lever, and wheel and axle, making it a compound machine.