P1-3; Motion, Work, Energy and Power Flashcards
What is the difference between Accuracy and Precision?
Accuracy: close to true value
Precise: repeatable results, close to each other
How do you read volumes in a test tube appropriately?
Take readings at eye level, and always take the reading from the bottom of the curve on the liquid’s surface.
Speed Equation?
Speed = Distance/Time
Conversion; Seconds - Minutes - Hours
Seconds /60 = Minutes/60 = hours
What is this time, in seconds?
1m 13s 48
73.48s
1 x 60 = 60
60 + 13.48 = 73.48s
If you run at 50m/s for 20s, how far have you ran?
V = dt
d = v x t
50 x 20 = 1000m
Distance / Time Graphs; How do they show changes in speed.
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.
Units of Acceleration/Acceleration Equation
Acceleration = Change in velocity over time
a = (delta)v \ t
Standard Units of Distance, Time, Speed and Acceleration
Distance = Metres (m)
Time = Seconds (s)
Speed = Metres per Second (ms-1)
Acceleration = Metres per Second, per Second (ms-2)
How do you work out acceleration(gradient) from a graph?
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.
What is the difference between weight and mass?
Weight is the concept of the effect of a gravitational field on a mass. (W = m g)
Recognize ALL VARIETIES of the Density Equation
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)
Express 8.92m^3 in cubic centimeters.
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
Recite Archimedes’ principle:
The volume of a body fully immersed in liquid can be deduced by the amount of liquid displaced by the object.
What are vectors?
Vectors are forces with magnitude and direction.
All forces are
They are most commonly represented my arrows.
List contact and non-contact forces:
Non-Contact: Contact:
Magnetic force Friction
Gravitational force Air resistance
Electrostatic force Tension
Recite Newtons 1st law:
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.
State Hooke’s law;
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
What is the “limit of proportionality” in a spring?
The limit of proportionality is where the spring reaches its full extension, and then breaks from overextension and is unusable.
Force on a spring equation
Force (N) = spring constant (N/m) x extension of spring (m)
Recal Newton’s Second Law:
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.
Recall: Newton’s 2nd law; Equation
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.
Pressure Calculation
p = F / A
Pressure (Pa) = Force (N) / Area (m^2)
Explain the relationship of pressure and surface area:
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.
If the force being applied is 15N, and the area it’s being applied to is 3m^2, what is the pressure?
15 / 3 = 5Pa
Define Work
Work done is the total amount of energy needed to move an object.
Work Equation
W = F x d
Work (J) = Force (N) x Distance (m)
List different types of energy:
Light, Sound, Electrical, Kinetic, Chemical,Gravitational Potential, Elastic Strain and Nuclear.
What energy transfers take place in a rocket?
Chemical Energy ~» Kinetic, Heat, Light, Sound Energy
What impacts the amount of kinetic energy an object has?
Speed and Mass
Recall: Kinetic Energy Equation
Kinetic Energy (J) =1/2 x Mass (Kgs) x Velocity^2 (ms^-1)
E = 1/2 m v^2
What is Power?
Power is how quickly you can get work done.
Recall: Power Equation
P = E / T
Power (W) = Energy (J) / Time (s)
What is the difference between Renewable and non-renewable resources?
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.
List some possible advantages to renewable energy:
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.
Recall: What is the water cycle?
Again the sun provides the energy to evaporate water, before it cools, condenses, falls as rain and flows back to the ocean.
What are the three different states of matter, and how do their particles act?
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.
What shows a material has stronger attraction between solid particles?
Melting points. High melting points have strong attractions between sold particles, low melting point materials have weak attractions between solid particles.
What is the name of the change of state from a solid to a gas?
Sublimation
What is temperature a measure of?
Average kinetic energy of particles.
Explain why sweating helps you cool down.
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.
What are factors for rate of evaporation?
Surface area
Wind / airflow
Temperature
Humidity
What is thermal expansion?
Thermal Expansion is when particles in a mass get further apart due to higher activity in the particles (heating up)
The difference between Thermal Insulators and Thermal Conductors.
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.
How can more activity in particles affect heat conduction?
When the particles begin to move more, they can get closer together, and that can cause increased transferral of movement between particles.
