PS 14.3 Formative

The actual mechanical advantage of a machine

• cannot be less than 1

• increases with greater friction

• is always less that the ideal mechanical advantage

• is always equal to the ideal mechanical advantage

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

Reducing friction in a machine

• decreases the actual mechanical advantage

• decreases the work output

• increases its efficiency

• increases its ideal mechanical advantage

Tags

NGSS.MS-ETS1-1

The efficiency of a machine is always less than 100% because

• a machine cannot have an ideal mechanical advantage greater than 1

• some work input is lost to friction

• the work input is too small

• the work output is too great

The _____ of a machine is the number of times that the machine increases the input force.

The mechanical efficiency of any machine is always _____ than 100 percent.

The percentage of work input that becomes work output is the _____ of a machine.

Tags

NGSS.MS-PS3-3

The _____ mechanical advantage of a machine is the mechanical advantage in the absence of friction.

A woman drives her car up onto wheel ramps to perform some repairs. If she drives a distance of 1.8m along the ramp to raise the car 0.3 m, what is the ideal mechanical advantage of the wheel ramps?

• 0.54

• 6.0

• 0.17

• 2.1

If a machine requires 1000 J of work input to produce a work output of 800 J, what is the efficiency of the machine?

• 0.8 %

• 100%

• 80%

• 20%

Tags

NGSS.HS-PS3-3