Work, Power and Simple Machines

What is the unit of work?

• joule
• newton/meter
• watt
• all of the above

Tags

NGSS.MS-PS3-5

If you exert a force of 10.0 N to lift a box a distance of 0.9 m, how much work do you do?

• 0.1 J
• 9.0 J
• 10.9 J
• 90.0 J

Tags

NGSS.MS-PS3-5

If you perform 40 joules of work lifting a 10-N box from the floor to a shelf, how high is the shelf?

• 0.3 m
• 20 m
• 4.0 m
• 400 m

Tags

NGSS.MS-PS2-4

NGSS.MS-PS3-5

The SI unit of power is the

• joule
• newton
• newton-meter
• watt

If you exert a force of 700 N to walk 6 m up a flight of stairs in 6 s, how much power do you use?

• 19 W
• 25,200 W
• 700 W
• 4,200

Tags

NGSS.MS-PS3-5

A machine is a device that can multiply

• force
• power
• work
• all of the above

The actual mechanical advantage of a machine

• cannot be less than 1
• decreases as the input distance increases
• increases with greater friction
• is less than the ideal mechanical advantage of the machine

If you know the input distance and the output distance of a machine, which of the following can you calculate?

• work
• actual mechanical advantage
• efficiency
• ideal mechanical advantage

If you have to apply 40 N of force on a crowbar to lift a rock that weights 400 N, what is the actual mechanical advantage of the crowbar?

• 0.1
• 10
• 40
• 16,000

Tags

NGSS.MS-PS2-2

A 120-m long ski lift carries skiers from a station at the foot of a slope to a second station 40 m above. What is the IMA of the lift?

• 0.3
• 3
• 40
• 160