Review of Chapter 4Review of Chapter 4Book “M”

Section 1Section 1What is work?Work is done on an object when

the object moves in the same direction in which the force is exerted.

How do you find work?Work = Force X Distance

Section 1 Continue Section 1 Continue What is power?Power is the rate at which work is

done.How do you calculate power?Power = work/time or power =

(force X Distance)/time

Section 2Section 2What is a machine?Machine is a device that allows you to

do work in a way that is easier or more effective

What is input force?The force you exerts on the machine.

Also know as the effort forceWhat is the output force?The force the machine exerts on an

object. Also know as the resistant force

Section 2 ContinueSection 2 ContinueWhat is input work?Input force time the input distanceWhat is output work?Output force time the output

distanceWhat are the three ways a

machine can make work easier?Changing force, changing

distance, and changing direction

Section 2 ContinueSection 2 ContinueWhat is Mechanical Advantage?A comparison of the input force

to the output force or the number of times a machine increases a force exerted on it.

How do you find?MA = output force/input force

Section 2 ContinueSection 2 Continue What is efficiency?The efficiency of a machine compares the

output work to the input work.How do you find efficiency?Efficiency = (output work/input work) X

100%What is the difference between ideal and

real machines?Ideal machines have 100% efficiency and

only exist on paper, and real machines lose some work due to friction, thus always having less than 100% efficiency.

Section 3Section 3What are the 6 basic kinds of simple

machines?Inclined plane, wedge, screw, lever,

wheel and axle, and pulleyWhat is an incline plane?Incline plane is a flat, sloped surfaceWhat is the ideal mechanical

advantage of an incline plane?IMA = length of incline/height of

incline

Section 3 continueSection 3 continueWhat is a wedge?A device that is thick at one end and

tapers to a thin edge at the other endHow do you find the mechanical

advantage?IMA = Length/widthWhat is a screw?A screw can be thought of as an incline

plane wrapped around a cylinderHow do you find the mechanical

advantage of a screw?IMA = length around the threads/length

of the screw

Section 3 continueSection 3 continueWhat is a lever?A rigid bar that is free to pivot, or

rotate, on a fixed pointWhat are the three types?First-class, second-class, and third-

classHow do you find the mechanical

advantage of a lever?IMA = distance from fulcrum to input

force(or effort distance)/Distance from fulcrum to output force(or resistant distance)

Section 3 continueSection 3 continueWhat is a wheel and axle?A simple machine made of two

circular or cylindrical objects fastened together that rotate about a common axis.

How do you find the mechanical advantage?

MA = radius of wheel/radius of axis

Section 3 continueSection 3 continueWhat is a pulley?A simple machine made of a grooved

wheel with a rope or cable wrapped around it.

What are the three types?Fixed pulley, movable pulley, and

block and tackleWhat is the mechanical advantage?IMA = number of sections of rope that

support the object.

Section 3 continueSection 3 continueWhat is a complex machine?A machine that utilizes two or

more simple machinesHow do you calculate the

mechanical advantage?IMA = the product of the

individual IMA of simple machines that make it up.