Chapter 7

Question 1

Work

Answer 1

involves the exchange of energy for some change in a physical system

Question 2

The SI unit for power

Answer 2

Watts

Question 3

Mechanical work

Answer 3

when a force acts on an object to move it in a direction parallel to the force vector

Question 4

Effort force

Answer 4

The force actually exerted on the simple machine

Question 5

Resistance force

Answer 5

The force needed to just begin moving the resistance

Question 6

Distance principle

Answer 6

To conserve work and energy, simple machines compensate for a smaller effort force by exerting that force over a longer distance

Question 7

Mechanical advantage

Answer 7

A measure of the reduction in effort to do a certain amount of work when using a simple machine

Question 8

Rotational equilibrium

Answer 8

The condition in which the sum of all the torques on a system is zero—the system will rotate either at a constant speed or not begin to rotate at all; the equivalent to Newton’s first law for linear motion

Question 9

Lever

Answer 9

simply a rigid bar that rests on a pivot point

Question 10

1st class lever

Answer 10

the fulcrum is located between the effort and the resistance

Question 11

2nd class lever

Answer 11

has its fulcrum at the end of the lever arm and the resistance between the fulcrum and the effort

Question 12

3rd class lever

Answer 12

A lever system in which the effort is between the fulcrum and the resistance

Question 13

Wheel and axel

Answer 13

Any rotational system having unrestricted range of motion

Question 14

Gear

Answer 14

a modified form of wheel and axle

Question 15

Effort arm

Answer 15

The moment arm of the effort force in a lever system

Question 16

Resistance arm

Answer 16

The moment arm of the load or resistance force in a lever system

Question 17

wedge

Answer 17

a three-dimensel object that uses inclined planes to exert a force to spread a material apart as it is forced into the material

Question 18

In the United States, how are bolts classified?

Answer 18

as a thread count

Question 19

power

Answer 19

the rate of doing work

Question 20

formula of power

Answer 20

p= W/delta t

Question 21

mechanical moment

Answer 21

the product of force and the distance from the pivot point where the force is applied

Question 22

what is the difference between a bolt and a screw?

Answer 22

a screw has ridges and a bolt has a wedge

Question 23

what is an example of an inclined plane?

Answer 23

loading ramps

Question 24

what is a pitch of the bolt thread?

Answer 24

metric fasteners are classified by the distance between adjacent threads in millimeters

Question 25

how does a wedge work?

Answer 25

they hold on to a material

Question 26

what is one way in ancient history is a simple machines is used?

Answer 26

a chariot- wheel and axle

Question 27

Simple machines

Answer 27

A basic mechanical device that either reduces effort or increases the magnitude of motion for a given input motion when doing a certain amount of work