PHY Flashcards
Displacement
the change in position of an object
Acceleration
the rate of change of speed
Speed
A rate of change of distance
Mass vs. weight
Mass is the amount of matter that makes up an object whereas weight is the force which gravity pulls something towards the earth
Newton’s Laws of Motion
Law of inertia: every body remains in a state of rest or uniform motion unless acted upon by a net external force.
Force = mass x gravity: The amount of acceleration of a body is proportional to the acting force and inversely proportional to the mass of the body.
Law of action and reaction: For every action there is an equal but opposite reaction. If an object A exerts a force on object B, then object B will exert an equal but opposite force on object A.
Force
a push, pull or twist
Friction
the force that opposes motion
Pressure
a measure of force applied to a particular area
Work
the energy transferred to or from an object via the application of a force along a displacement
Power
the amount energy transferred per unit time
Kinetic energy
the energy an object has due to its motion
Air resistance
the result of collisions of the objects leading surface with air molecules
Terminal velocity
highest constant speed an object reaches when falling through the air
Gravitational potential energy
the potential energy an object has because of its height
Conductor
Materials that allow the electrical flow of charge
Insulator
materials that do not allow the flow of electrical charge
Voltage in a series circuit
Shared for the components connected to the series
Current in a series circuit
Same for components connected in a series
Total resistance in a series circuit
All individual resistances added up
Voltage in a parallel circuit
Same for all components connected in a parallel
Current in a parallel circuit
All individual current added up
Total resistance in a parallel circuit
All individual resistance added up (1/Rp = 1/R1 + 1/R2 + R/3)
Voltage
the difference in electrical potential energy between two points in a circuit
Current
The rate of flow of electrical charge
Resistance
The force that opposes the flow of electrical current in a circuit
Electric Field
a region in which a charged object experiences a force
Electrostatic forces
forces between charged particles causes movement between these charge particles
What does a curved line in a distance-time graph represent?
Accelerating/Decelerating
What does a positive straight line in a distance-time graph represent?
Constant speed
What does a horizontal line in a distance-time graph represent?
Stationary
What does a positive straight line in a displacement-time graph represent?
Steady speed
What does a horizontal line in a displacement-time graph represent?
Stationary
What does a negative straight line in a displacement-time graph represent?
Steady speed returning to start
What does a displacement-time graph show
If an object is moving backwards to forwards
What does a positive straight line on a speed-time graph represent?
Constant positive acceleration
What does a horizontal line on a speed-time graph represent?
Constant speed
What does a negative straight line on a speed time graph represent?
Constant negative acceleration
What does a curved line on a speed-time graph represent?
Accelerating/decelerating
How do you calculate distance travelled on a speed-time graph?
Find area
Describe the relationship between area and pressure
If the surface area is increased, the pressure on the snow decreases.
If surface area is decreased, the pressure on the snow increases.
Why is it that smaller surface area = more pressure? (vice versa)
The same force (weight of object) is applied over a smaller area.
Law of conservation
Energy can not be created or destroyed but can be transformed
Factors that affect resistance
Length, thickness and temperature
Explain the forces of attraction of a positive and negative charge referring to electric field
The positive charge inside an electric field will experience a force towards the negative charge.
Describe how we can differentiate the positive and negative parallel plates in a battery.
Longer line - positive
Shorter line - negative
What way do the arrows point when drawing electrical field between parallel plates?
Away from positive
Positive –> Negative
How do you calculate strength of the electric field?
Electric field = Voltage / distance between plates
What is the unit for electric field?
V/m-1
Why is the force needed less when dragging an object up a ramp instead of lifting it straight up?
The force needed is less for the ramp as the work done is the same , but the distance the work is done over is greater therefore force vert is greater than force ramp. (W = F x d)
Explain whether or not the power needed to drag an object is more or less than the power needed to lift the object straight up
The power to drag to the top of the ramp would be less than lifting straight up as it took longer to drag up. This means the same work is done but is shared over a greater period of time, so the power is reduced. (P = W / t)
