Conceptual Physics (Exam 2)

Question 1

What is work?

Answer 1

Work= applying a force to an object over a specific distance.

Question 2

What has to be present for work to be done?

Answer 2

1. Force Applied
2. Distance Traveled
3. Force has to be in the same direction as motion.

Question 3

Work Equation

Answer 3

W = F x D
Labeled in Joules

Question 4

What is power?

Answer 4

Power: The rate at which work is done

Question 5

How are power and work related?

Answer 5

Power and work are inversely related…as one increases the other decreases.

Question 6

Power Equation

Answer 6

Power = Work/Time
Labeled in Watts

Question 7

What is energy?

Answer 7

Energy: The ability to do work.
All energy types are labeled in Joules.

Question 8

What are the different types of energy?

Answer 8

1. Kinetic Energy
2. Potential Energy
3. Thermal Energy
4. Light
5. Sound
6. Mechanical Energy
7. Wind
8. Nuclear
9. Geothermal

Question 9

What is Potential Energy?

Answer 9

Potential energy is STORED energy
1. Elastic (Rubber Band)
2. Gravitational (Positione above Earth)
3. Chemical (Chemical Reaction)

Question 9

GPE

Answer 9

PE = mgh (mass (kg), g = acceleration due to gravity (9.8 m/s2), h = height in meters)
IF THE MASSES ARE EQUAL AND HEIGHT ARE EQUAL GPE IS EQUAL, AND THE AMOUNT OF WORK TO GET TO THE GPE IS EQUAL.

Question 9

What is Kinetic Energy?

Answer 9

Kinetic Energy is energy in MOTION
KE = 1/2 mv 2
Labeled in Joules
IN ORDER FOR OBJECTS TO MOVE KINETIC ENERGY; NEED TO KNOW MASS AND IT HAS TO MOVE.

Question 10

Law of Conservation of Energy

Answer 10

States that energy is neither created nor destroyed, but can be transformed from 1 form to another.
Ex: Kinetic Energy to heat; Potential energy to sound.

Question 11

Work to Energy

Answer 11

Work = Change in Energy

Question 12

What is Thermal Energy?

Answer 12

Thermal Energy: Amount of heat an object possesses. This is based on physical characteristics such as mass & composition.

(It is possible for an object to have more energy, but not change its temperature (Because mass has differences))

Question 13

What is heat?

Answer 13

Heat: Flow of Thermal Energy.
Always occurs from warmer objects to colder objects.

Measure of the TOTAL kinetic energy of a system.

Question 14

What is temperature?

Answer 14

The measure of the AVERAGE kinetic energy of a system.

Question 15

How do Thermal Energy & Temperature Relate/Differ

Answer 15

Thermal energy and temperature have a direct relationship.

Relationship: As 1 increases, the other increases.

Differ: Temperature is the measure of AVERAGE kinetic energy while Thermal Energy is the measure of TOTAL kinetic energy of the body.

Question 16

What is Specific Heat?

Answer 16

The amount of energy required to raise the temperature of 1 g of a substance 1 C

Specific Heat depends on MASS and The MATERIAL of the object.

Insulators: have HIGHER specific heats than conductors

Question 17

How do we measure heat and temp?

Answer 17

1. Celsius (°C)
2. Kelvin (K).
3. Fahrenheit (expressed as °F)
   Thermometers measure temperature by using materials that expand or contract when heated or cooled.

Question 18

What are Thermal Insulators?

Answer 18

Insulators are materials that don’t allow thermal energy to pass through easily.

Question 19

What are Thermal Conductors?

Answer 19

Conductors are materials that allow thermal energy to pass easily through.

Question 20

What simple machines are in the Lever Family?

Answer 20

Lever, Pulley, Wheel and Axle

Question 21

What simple machines are in the Inclined Plane Family?

Answer 21

Inclined Plane, Wedge, Screw

Question 22

What is Mechanical Advantage?

Answer 22

The number of times that the effort force is multiplied.

Question 23

What is AMA?

Answer 23

Actual Mechanical Advantage (Fr/Fe)
Since the “real-world” is not perfect…this is the mechanical advantage that we “actually” get out of a machine.

Is the ratio of the output forces exerted by a machine to input force applied to it.
It represents how much the machine amplifies it increases input force
AMA is always less than IMA due to factors such as friction and other inefficiencies in the machine.

Question 24

What is IMA?

Answer 24

IMA: Ideal Mechanical Advantage (De/Dr)
If all things were “perfect” this would be the number of times our effort force is multiplied.

IMA is the ratio of the distance over which the output force is exerted to the distance over which the input force is applied
It represents the theoretical mechanical advantage of the machine in the absence of friction and other inefficiencies.
IMA is calculated based on physical dimensions and geometry.

Question 25

Why will AMA never be equal to the IMA?

Answer 25

Because of friction, you have to overcome friction. The least amount of friction, the more of a chance you get to ideal.
Reduce friction, and change the type of friction.

AMA takes into account the actual performance, of IMA based on ideal conditions.
Friction reduces the AMA of the machine compared to IMA.

Question 26

Lever

Answer 26

a rigid bar resting on a pivot

Question 27

Pulley

Answer 27

a wheel with a grooved rim around which a cord passes

Question 28

Wheel and Axle

Answer 28

a simple machine consisting of a large disc wrapped around a smaller rod

Question 29

Inclined Plane

Answer 29

a plane surface raised to the horizon, or forming with a horizontal plane any angle but a right angle.

Question 30

Wedge

Answer 30

a piece of hard material with two principal faces meeting in a sharply acute angle, for raising, holding, or splitting objects.

Question 31

Screw

Answer 31

a simple machine consisting of an incline plane wrapped around a rod.