Year 11 Term 1 Flashcards
Define force
At its core, force is an interaction between 2 objects; the interactions are push/pull and attraction/repulsion
Identify whether force is scalar or vector quantity
Force is a vector quantity
True or False: Force exist in pairs
True (action-reaction forces)
Identify the purpose of free-body diagrams
Free-body Diagrams is a technique to illustrate the external forces acting on a body
When the net force of an object is zero, the object is in:
When the net force of an object is zero, the object is in:
- Static Equilibrium
- Dynamic Equilibrium
Define external forces
External Forces are between the system and its surroundings
Define internal forces
Internal Forces are between components within the system
True or False: Given that F_net = 0, the components in the x and y-direction = 0
True
Recall Newton’s First Law of Motion
Newton’s First Law of Motion states a body at rest remains at rest, or, if in motion, remains in motion at a constant velocity unless acted upon by a net external force.
Recall Newton’s Second Law of Motion
Newton’s Second Law of Motion states the net force is equal to the product of mass and acceleration (F_net=ma)
Recall Newton’s Thrid Law of Motion
Newton’s Third Law of Motion states for each action (force), there is an equal and opposite reaction
Define weight
Weight is the force acting on an object due to acceleration of gravity
Define mass
Mass is the amount of particles in an object
Define normal force
Normal force (N) is a perpendicular force to the surfaces in contact, hence is a contact force
Weight formula
W = mg
Define tension
A force along the length of a medium, especially a force carried by a flexible medium, such as a rope or string
Identify whether tension is a scalar or vector quantity
Tension is a vector quantity
Tension formula
T = mg + ma
Define friction
Friction is a force that opposes relative motion between two surfaces in contact
Types of Friction
Kinetic friction
- Sliding friction
- Rolling friction
Static friction
Define fluid friction
Fluid Friction is the resistance created through motion in a medium of liquid or gas; drag
Kinetic friction formula
f_k = μ_k N
Static friction formula
f_s ≤ μ_s N
True or False: Friction is proportional to the surface area
False: Friction is proportional to the normal force and contact area not surface area as contact area ≠ surface area
Define coefficient of friction
The coefficient of friction is the ratio of the friction force and the normal force; μ = Ff /N
Coefficient of static friction formula
μ_s = tanθ_c (gradient of the critical angle)
Define terminal velocity
Terminal Velocity is the highest velocity of an object due to gravity as the fluid friction = acceleration due to gravity
Define work
Work is the energy transferred to or from an object via the application of force along a displacement
Identify whether work is scalar or vector quantity
Work is a scalar quantity
The work-energy theorem states:
The work-energy theorem states that the net work done equals the change in energy
Work is equal to the area under what graph
Work is equal to the area under a Force-displacement Graph
Recall the shortcut for finding the area under a graph
The shortcut is to find the area under the average, which forms a rectangle; easier to solve
Define power
Power is the amount of energy transferred or converted (or work) per unit time
Identify whether power is a scalar or vector quantity
Power is a scalar quantity
Define gravitational potential energy
Gravitational potential energy is the energy an object possesses because of its position in a gravitational field
Define zero reference point
Zero Reference Point is an arbitrary point where we set h = 0 and hence, gravitational potential energy to be zero
Define total mechanical energy (TME)
Total Mechanical Energy (TME) is the sum of the kinetic and potential energy
True or False: Total mechanical energy is always conserved
False: Total mechanical energy is conserved unless acted upon by nonconservative forces, i.e. friction
Explain why if an object took an arbitrary path, only the vertical component is considered
If an object travels along some arbitrary path, the gravitational potential energy is only dependent on the vertical distance (h). This is as if one splits the path into the vertical and horizontal components, the horizontal component is discarded as it is perpendicular to the displacement
Explain why forces perpendicular to the displacement do not affect the work done
Forces perpendicular to the displacement do not affect the work done as the critical angle is 90 and cos(90) = 0
Define momentum
Momentum is the quantity of motion of a moving body
Momentum formula
p = mv
Identify whether momentum is a scalar or vector quantity
Momentum is a vector quantity
Impulse formula
I = FΔt
I = m(v-u) = Δp
Impulse is equal to the area under what graph
Impulse is equal to the area under a force-time graph
Define elastic collision
Elastic Collision is one in which both momentum and kinetic energy is conserved
Define inelastic collision
Inelastic Collision is one in which only momentum is conserved
Define wave
A wave is a propagation of disturbances from place to place
True or False: The particles in a wave travel from the source to where the wave is
False, the particles themselves do not travel
Recall the types of waves
Mechanical waves
- Longitudinal waves
- Transverse waves
Electromagnetic waves
Contrast mechanical waves and electromagnetic waves
Mechanical waves require a medium to propagate while electromagnetic waves do not, in fact, a medium slows the wave down
Contrast transversal and longitudinal waves
For a transverse wave, the direction of particle oscillation is perpendicular to the direction of wave motion. On the other hand, for a longitudinal wave, the direction of particle oscillation is parallel to the direction of wave motion
Define crest
Crest is the highest point of a transverse wave or a particle’s maximum displacement upwards
Define trough
Trough is the lowest point of a transverse wave or a particle’s maximum displacement downwards
Define wavelength
Wavelength (λ) is the distance between the identical points on a wave
Define amplitude
Amplitude (a) is the distance from the equilibrium position to either the crest or trough
Define equilibrium position
Equilibrium Position is the middle point of the wave
Define period
Period (T) is the time it takes for one complete wavelength to pass a fixed point
Define frequency
Frequency (f) is the number of vibrations per second performed by the source of the waves
True or False: Frequency is proportional to the period
False: Frequency is inversely proportional to the period; f = 1/T
Define compression
Compression is the areas of increased pressure
Define rarefaction
Rarefaction is the areas of decreased pressure
Identify what can be used to graph waves
Graphing Waves:
- Displacement-distance graphs
- Displacement-time graphs
Inverse Square Law
I = P/4πr^2
Alternate intensity formula
Alternate formula: I = K/d^2 where K is a constant
K = I_1 (d_1)^2 = I_2 (d_2)^2
Define reflection
Reflection is a phenomenon where a wavefront changes direction at an interface between two different media so that the wavefront returns into the medium from which it originated
Define diffraction
Diffraction is a phenomenon where a wave diverges as it passes through an aperture or around objects; only occurs when the wavelength and the length of the slit is similar
Define resonance
Resonance is a phenomenon in which the particles in a wave vibrating at a certain frequency can cause other surfaces to vibrate at the same frequency upon contact
Define superposition
Superposition is a phenomenon when waves occupy the same space at the same time, causing the waves to combine
Define standing waves
Standing Waves are a combination of two waves moving in opposite directions, each having the same amplitude and frequency
Recall the term for the lowest frequency of a standing wave
First harmonic
Define first harmonic
First Harmonic (fundamental frequency) is a standing wave with the lowest possible frequency
Define node
Node is a point along a standing wave where the wave has minimum amplitude
Define antinode
Antinode is a point along a standing wave that alternates between the crest and trough
Wavelength formula for open both ends
λ = 2L/n where n is the n-th harmonic
Wavelength formula for open one end
λ = 4L/2n-1 where n is the n-th harmonic
Explain why the even harmonics are skipped for when there is one end open?
The even harmonics are skipped as the 2nd harmonic is 3 times the first harmonic, hence it is the third harmonic and this pattern continues
Given that the doppler effect is:
f’ = f(v ± v_o/v ± v_s)
Identify each component
f ’ is the observed frequency
f is the actual frequency
v is the velocity of the sound waves
v_o is the velocity of the observer
v_s is the velocity of the source
Recall The Law of Reflection
The Law of Reflection states that the angle of reflection equals the angle of incidence where the angle is measured relative to the normal
Define refraction
Refraction is the changing of a light ray’s direction when it passes through variations in matter
Index of Refraction formula
Index of Refraction is n = c/v where c is the speed of light and v is the speed of light in the medium
Explain why the index of refraction is ≥ 1
As the formula is c/v and light travels slower in denser mediums, c > v and hence the index of refraction is ≥ 1
Snell’s Law formula
Snell’s Law (Law of Refraction) states n_1 sinθ_1 =n_2 sinθ_2 where n’s are the refractive index and θ’s are relative to the normal
Define critical angle
The critical angle (θ_c) is when the incident angle (θ_1) produces an angle of refraction of 90°
Define Total Internal Reflection
Total Internal Reflection is if the incident angle is greater than the critical angle, then all the light is reflected back into the original medium
Define dispersion
Dispersion is the spreading of white light into the visible spectrum of wavelengths in the order - [ROY-G-BIV]
Define focal point
Focal Point (F) is the point at which the light rays intersect
Define focal length
Focal Length (f) is the distance from the centre of the lens to the focal point
True or False: A ray that passes through the centre of a lens does not change direction
True
Define principal axis
Principal Axis goes through the centre of the lens/mirror surface and is perpendicular to said surface
Identify which lens converge and which diverge
Concave Lens diverge and Convex Lens converge
Identify which mirrors converge and which diverge
Concave Mirrors converge and Convex Mirrors diverge
Identify how one could describe an image
Descriptions of an Image Formed:
- Real or Virtual
- Magnified or diminished
- Upright or Inverted
Identify a basic method to draw rays
Always draw from the top of the object:
- Draw a ray parallel to the principal axis
- Draw a ray at the centre
- Draw a ray at the focal point
