PHYSICS

Question 1

Physics is the study of?

Answer 1

Matter and energy

Question 2

What is matter?

Answer 2

Anything that has mass and takes up space

Question 3

What is mass?

Answer 3

It is the measure of quantity of matter in an object.

MASS = WEIGHT / ACCELERATION DUE TO GRAVITY

The more mass an object has, the more it will weigh under the earth’s force of gravity

WEIGHT = MASS X GRAVITY

Question 4

What is Attraction?

Answer 4

Attraction is the mutual force acting between particles of matter, which tends to draw them together.

Question 5

What is Porosity?

Answer 5

It means having pores or spaces where smaller particles may fir when a mixture takes place.

Question 6

What is Impenetrability?

Answer 6

It means that no two objects can occupy the same place at the same time.

Question 7

What is Density?

Answer 7

A substance’s weight per unit volume. You must know its weight and volume to know its density. Its weight is divided by its volume to find the weight per unit volume.

LBs per cubic foot OR grams per cubic centimeter

Question 8

What is specific gravity?

Answer 8

Specific gravity is calculated by comparing the weight of a definite volume of the given substance with the weight of an equal volume of water.

SG = weight of the substance / weight of an equal volume of water

OR

SG = density of the substance / density of water

Question 9

The unite of measure in the English system is the?

Answer 9

BTU (British Thermal Unit)

Question 10

The unit of heat in the metric system is the?

Answer 10

Calorie

Question 11

One BTU unit is equal to?

Answer 11

778 ft-lbs of work

Question 12

What is specific heat?

Answer 12

The heat required to raise the temp of material 1 degrees Celsius compared to the heat required to raise the temp of the same amount of water.

Question 13

If a double-acting actuating cylinder in a 3000 psi system has a piston with a surface area of three square inches on the extension side, and a rod with a cross section area of one square inch attached to the piston on the other side, approximately how much force will the actuator be able to produce when retracting?

a) 9,000 lbs
b) 6,000 lbs
c) 3,000 lbs

Answer 13

3 minus 1 = 2

2 x 3000 = 6000 lbs

Question 14

If the fluid pressure is 800 PSI in a 1/2” line supplying an actuating cylinder with a piston area of 10 sq in, the force exerted on the piston will be:

a) 4000 lbs
b) 8000 lbs
c) 800 lbs

Answer 14

Force = pressure x area

8000 = 800 x 10

8000 lbs

Question 15

Name three methods of heat transfer

Answer 15

Conduction, convection, radiation

Question 16

A device that is used to measure a specific gravity of liquids is?

Answer 16

Hydrometer

Question 17

Stored energy is called:

Answer 17

Potential energy

Potential energy = weight x height

Question 18

Energy in motion is called:

Answer 18

Kinetic energy

Kinetic energy = 1/2 mass x velocity squared

Question 19

If a __________ is applied, the tendency will be for the object to move

Answer 19

Force

Question 20

Two factors are involved with measurable work are:

Answer 20

Force and movement through a distance

Question 21

The force of friction for objects mounted on wheels or rollers is called:

Answer 21

Rolling friction

Question 22

The concept of power involves work but adds the consideration of

Answer 22

TIME

Question 23

What is torque?

Answer 23

A force acting along a distance. Its something that creates TWISTING and tries to make something rotate.

Torque = force x distance

Question 24

What is a simple machine?

Answer 24

Any device with which work may be accomplished

Question 25

Name six simple machines

Answer 25

a) Lever
b) Pulley
c) the Wheel and Axle
d) the Inclined Plane
e) the screw
f) the gear

Question 26

What are the units of force?

Answer 26

One pond of force is equal to 4.448 newtons

Force = mass x acceleration

Question 27

What is work?

Answer 27

Work is accomplished when an object is displaced some distance against a resistive force.

WORK = Force x distance

Question 28

What are three kinds of friction?

Answer 28

1) Starting or static friction - friction required to START an object moving
2) Sliding friction - pertains to the friction produced AFTER the object has been set in motion
3) rolling friction - force for objects mounted on wheels/rollers

Question 29

What is POWER?

Answer 29

Power = force x distance divided by time

Question 30

What the formula of the relationship of TORQUE and HORSEPOWER?

Answer 30

TORQUE = HORSEPOWER x 5,252 divided by its RPM

Question 31

What is a first class lever?

Answer 31

A lever where the fulcrum is located between the effort and the resistance. A good example is the seesaw.

Effort (E) x Effort Arm (L) = Resistance (R) x Resistance Arm (l)

Question 32

A first class lever is used to to lift a 500lb weight. The distance from the weight to the fulcrum is 12 inches and from the fulcrum to the applied effort is  60 in.
How much force is required to lift the weight?

Answer 32

E x 60in = 500lb x 12in
E= 500lb x 12 in / 60in
E= 100lb

The mechanical advantage of this lever is:

Mechanical Advantage = Force Out / Force In
= 500 Lb / 100lb
= 5 or 5 to 1

Question 33

What is a second class lever?

The distance from the center of the wheel to the handles on the wheelbarrow is 60 inches. The weight in the bucket is 18in frm the center of the wheel. If 300lb is placed in the bucket, how much force must be applied at the handles to lift the wheelbarrow?

Answer 33

The second class lever has the fulcrum at one end and the effort is applied at the other end. A wheelbarrow is a good example.

Effort (E) x Effort Arm (L) = Resistance (R) x Resistance Arm (l)

E x 60in = 300lb x 18in
E= 300lb x 18 in / 60in
E= 90lb

Mechanical Advantage = Force Out / Force In
= 300 Lb / 90lb
= 3.33 to 1

Question 34

What is a third class lever?

Answer 34

The fulcrum is at one end of the lever and the weight or resistance to be overcome is at the other end, with the effort applied at some point in between.

A retractable landing gear on an airplane is a good example.