Work, Power, Simple Machines, Mechanical Advantage

A girl pushes on a parked car with a force of 500N. The car does not move. How much work does the girl do?

• 500 N

• 500 J

• Zero

• Can't be determined-need a distance

A man pushes a crate along a factory floor by exerting a force of 50 N. If the crate moves a distance of 4.0 m, how much work does the man perform?

• 13.75 J

• 200 N

• 200 J

• 13.75 N

A weightlifter presses a 400N weight 0.5m over his head in 2 seconds. what is the power of the weightlifter?

• 400 watts

• 25 watts

• 100 N

• 100 watts

What is the mechanical advantage of a ramp that is 10 meters long and 2 meters high?

• 20

• 5

• 8

• 0.20

A machine is a device that

• requires less work to do a given task

• decreases the amount of work done by a given force

• increases energy

• can multiply and change the direction of an input force

Tags

NGSS.MS-ETS1-1

A first-class lever has the

• fulcrum at one end and the output force between the fulcrum and the input force

• fulcrum at one end and the input force between the fulcrum and the output force

• fulcrum in the middle

• input force in the middle

A wheelbarrow is a compound machine that contains a

• first-class lever

• second-class lever

• third-class lever

• fourth-class lever

Which of the following is an example of a third-class lever?

• a nutcracker

• lifting a weight with forearm

• a crow bar

• a screw

Which of the following is NOT a simple machine?

• a lever

• a pair of scissors

• a screw

• a wheel and axle

What is the mechanical advantage of the single fixed pulley shown here?

• 1

• 1.5

• 2

• 3