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?

(a)  

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 (a)   of a machine is the number of times that the machine increases the input force.

The mechanical efficiency of any machine is always (a)   than 100 percent.

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

Tags

NGSS.MS-PS3-3

The (a)   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