P1-3; Motion, Work, Energy and Power

Question 1

What is the difference between Accuracy and Precision?

Answer 1

Accuracy: close to true value
Precise: repeatable results, close to each other

Question 2

How do you read volumes in a test tube appropriately?

Answer 2

Take readings at eye level, and always take the reading from the bottom of the curve on the liquid’s surface.

Question 3

Speed Equation?

Answer 3

Speed = Distance/Time

Question 4

Conversion; Seconds - Minutes - Hours

Answer 4

Seconds /60 = Minutes/60 = hours

Question 5

What is this time, in seconds?

1m 13s 48

Answer 5

73.48s

1 x 60 = 60
60 + 13.48 = 73.48s

Question 6

If you run at 50m/s for 20s, how far have you ran?

Answer 6

V = dt

d = v x t

50 x 20 = 1000m

Question 7

Distance / Time Graphs; How do they show changes in speed.

Answer 7

The distance traveled over time = Speed, so if there is no change in distance, the object is stationary. It is moving at the same speed constantly, there will be a steady and constant change in distance. If the object is accelerating, a curve will form.

Question 8

Units of Acceleration/Acceleration Equation

Answer 8

Acceleration = Change in velocity over time
a = (delta)v \ t

Question 9

Standard Units of Distance, Time, Speed and Acceleration

Answer 9

Distance = Metres (m)
Time = Seconds (s)
Speed = Metres per Second (ms-1)
Acceleration = Metres per Second, per Second (ms-2)

Question 10

How do you work out acceleration(gradient) from a graph?

Answer 10

Rise/Run or y/x

Find a point on the graph where the data meets both the x and y axis, and then divide y/x to get acceleration.

Question 11

What is the difference between weight and mass?

Answer 11

Weight is the concept of the effect of a gravitational field on a mass. (W = m g)

Question 12

Recognize ALL VARIETIES of the Density Equation

Answer 12

p (density in kg/m3) = m(kg) / V(m3)

m(kg) = p (density in kg/m3) x V(m3)

V(m3) = m(kg) / p (density in kg/m3)

Question 13

Express 8.92m^3 in cubic centimeters.

Answer 13

Length : 100cm = 1m
Area : 10,000cm^2 = 1m^2
Volume : 1,000,000cm^3 = 1m^3

8.92 x 1,000,000 = 8,920,000cm^3

Question 14

Recite Archimedes’ principle:

Answer 14

The volume of a body fully immersed in liquid can be deduced by the amount of liquid displaced by the object.

Question 15

What are vectors?

Answer 15

Vectors are forces with magnitude and direction.
All forces are

They are most commonly represented my arrows.

Question 16

List contact and non-contact forces:

Answer 16

Non-Contact: Contact:

Magnetic force Friction
Gravitational force Air resistance
Electrostatic force Tension

Question 17

Recite Newtons 1st law:

Answer 17

If a body is at rest and the forces acting on it are balanced then the body will remain at rest.

If a body is moving and the forces acting are balanced then the body will keep moving at constant speed in a straight line.

Question 18

State Hooke’s law;

Answer 18

Hooke’s law states that force applied to a spring is directly proportional to the extension experienced by the spring, and that constant of proportionality is k, the spring constant, during elastic behaviour.

F = k x

Question 19

What is the “limit of proportionality” in a spring?

Answer 19

The limit of proportionality is where the spring reaches its full extension, and then breaks from overextension and is unusable.

Question 20

Force on a spring equation

Answer 20

Force (N) = spring constant (N/m) x extension of spring (m)

Question 21

Recal Newton’s Second Law:

Answer 21

Newton’s Second Law of Motion states that when an unbalanced force acts on an object:

• the direction of the object’s acceleration is the same as the direction of the unbalanced force
• the magnitude of the object’s acceleration varies in direct proportion with the size of the unbalanced force
• the magnitude of the object’s acceleration varies inversely with the mass of the object.

Question 22

Recall: Newton’s 2nd law; Equation

Answer 22

Newton’s Second Law of Motion can be written as the following relationship:
F = ma
where:
F = unbalanced force m = mass a = acceleration

Note that when you use this relationship, F always stands for unbalanced force.

Question 23

Pressure Calculation

Answer 23

p = F / A

Pressure (Pa) = Force (N) / Area (m^2)

Question 24

Explain the relationship of pressure and surface area:

Answer 24

Surface area and pressure are related because the amount of pressure put on a surface depends on the amount of surface it’s spread over.

Question 25

If the force being applied is 15N, and the area it’s being applied to is 3m^2, what is the pressure?

Answer 25

15 / 3 = 5Pa

Question 26

Define Work

Answer 26

Work done is the total amount of energy needed to move an object.

Question 27

Work Equation

Answer 27

W = F x d

Work (J) = Force (N) x Distance (m)

Question 28

List different types of energy:

Answer 28

Light, Sound, Electrical, Kinetic, Chemical,Gravitational Potential, Elastic Strain and Nuclear.

Question 29

What energy transfers take place in a rocket?

Answer 29

Chemical Energy ~» Kinetic, Heat, Light, Sound Energy

Question 30

What impacts the amount of kinetic energy an object has?

Answer 30

Speed and Mass

Question 31

Recall: Kinetic Energy Equation

Answer 31

Kinetic Energy (J) =1/2 x Mass (Kgs) x Velocity^2 (ms^-1)

E = 1/2 m v^2

Question 32

What is Power?

Answer 32

Power is how quickly you can get work done.

Question 33

Recall: Power Equation

Answer 33

P = E / T

Power (W) = Energy (J) / Time (s)

Question 34

What is the difference between Renewable and non-renewable resources?

Answer 34

Renewable resources:
As we use them, they are replaced by natural processes. We are unlikely to run out of these resources.

Non-renewable resources:
These resources are not replaced quickly by natural processes. If we keep using them, they will run out.

Question 35

List some possible advantages to renewable energy:

Answer 35

Can often be generated where they are used.

Most don’t have ongoing greenhouse emissions.

Once the equipment is paid for, the generation is free / cheap.

Fewer toxins and health hazards at point of use.

Question 36

Recall: What is the water cycle?

Answer 36

Again the sun provides the energy to evaporate water, before it cools, condenses, falls as rain and flows back to the ocean.

Question 37

What are the three different states of matter, and how do their particles act?

Answer 37

Soldis: Particles in solids have a regular arrangement and are closely packed. They have very little movement.

Liquids: Have a random arrangement of particles that are still close, but have some energy and move.

Gases: Random arrangement of particles that are far apart, and very active.

Question 38

What shows a material has stronger attraction between solid particles?

Answer 38

Melting points. High melting points have strong attractions between sold particles, low melting point materials have weak attractions between solid particles.

Question 39

What is the name of the change of state from a solid to a gas?

Answer 39

Sublimation

Question 40

What is temperature a measure of?

Answer 40

Average kinetic energy of particles.

Question 41

Explain why sweating helps you cool down.

Answer 41

As your sweat evaporates, the liquid which remains cools down (lower average kinetic energy).
This repeats until all the sweat evaporates, gradually taking more and more heat energy as it goes.

Question 42

What are factors for rate of evaporation?

Answer 42

Surface area

Wind / airflow

Temperature

Humidity

Question 43

What is thermal expansion?

Answer 43

Thermal Expansion is when particles in a mass get further apart due to higher activity in the particles (heating up)

Question 44

The difference between Thermal Insulators and Thermal Conductors.

Answer 44

Thermal Insulator: Keeps thermal (heat) energy in one place, stops it moving / being transferred.

Thermal Conductor: Allows thermal energy to be transferred from one place to another.

Question 45

How can more activity in particles affect heat conduction?

Answer 45

When the particles begin to move more, they can get closer together, and that can cause increased transferral of movement between particles.