Work and Simple Machines

How much work is done when you push a sled across the snow with a force of 70.0 N for a displacement of 20.0 m?

• 1,400 J

• 1,400 W

• 70 N

• 4,100 J

It takes a car 130 seconds to pull a trailer 5 m down the road and exerts a horizontal force of 7,000 N. At what power level is the car performing?

• 54 J

• 54 W

• 269 J

• 269 W

A crane can lift a 500 kg mass to height of 30 m in 2 minutes. The work done by the crane is:

(*You must compute the force of the mass being lifted first)

• 10,000 J

• 30,000 J

• 150,000 J

• 75,000 J

Tags

NGSS.MS-PS3-5

How much work is done by a 500 Watt car engine in 10 minutes?

• 3,000 J

• 300,000 J

• 5,000 J

• 300,000 W

What is a device that does work with only one movement and changes the size or direction of a force?

• Simple machine

• Ideal machine

• Compound machine

• Appliance

The work output of a machine divided by the work input is the ______________ of the machine.

• Efficiency

• Resistance

• Effort

• Power

Tags

NGSS.MS-ETS1-1

A machine that changes only the direction of a force has a mechanical advantage of:

• A value equal to 1

• A value less than 1

• A value greater than 1

• A value equal to 2

If trying to move a very heavy piano using a ramp should you choose a short ramp or a long ramp? Explain why.

• The shorter ramp because it will reduce the distance and friction needed to move the piano.

• The long ramp because it will increase the distance and the force needed to move the piano.

• The longer ramp because it will reduce the force needed to move the piano.

• The short ramp because it will reduce the distance needed to move the piano.

Tags

NGSS.MS-ETS1-1

NGSS.MS-PS2-2

The mechanical advantage of a pulley system is equal to the number of:

• Fixed pulleys in the system

• Movable pulleys in the system

• Sections of rope pulling up an object

• None of these

How does using a pulley make moving heavy objects easier?

• Doubles the force required to move an object

• Changes the direction of the force needed to lift the object

• Decreases the force required and changes the direction of the force needed to lift the object

• Decreases the force required to lift the object

Tags

NGSS.MS-ETS1-1