# Unit 2

Unit 2 questions (mixed topics)

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• Created by: Taff6617
• Created on: 03-06-14 19:03
What is the difference between a scalar quantity and a vector quantity?
Vectors have magnitude and direction, while scalars only have magnitude
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Name a scalar quantity
Any of the following (or other as appropriate): distance, speed, mass, length, volume, density, area, pressure, power, energy, temperature
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Name a vector quantity
Any of the following (or other as appropriate): displacement, velocity, acceleration, force, weight, lift, drag
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State conditions for equlibrium
Balance forces; (and the principle of moments)
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What is the definition of a moment?
Moment of a force about a point is equal to the force x perpendicular distance between the pivot and line of action of the force
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What is the principle of moments?
(For equilibrium), the sum of the clockwise moments must equal the sum of the anti-clockwise moments (at any point)
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What is a couple?
A pair of equal and opposite forces acting on a body, but not at the same point
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What does a horizontal line mean on a velocity-time graph?
A constant velocity
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What does a line with a positive gradient mean on a velocity-time graph?
Acceleration
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What does a horizontal line mean on a distance-time graph?
No motion
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On a distance-time graph, it the line rises up, then lowers back to the x-axis, what has happened?
The object has returned to its original position
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On a distance-time graph, what does a straight line mean?
Constant velocity
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The value for acceleration due to gravity?
9.81ms^-2
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What is Newton's First Law?
Objects stay at rest or in uniform motion unless acted on by an external force
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What is Newton's Second Law?
F=ma (the force applied to an object is proportional to the mass and acceleration as a result of that force)
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What is terminal velocity?
The velocity of the object when the sum of the drag force equals the downward force of gravity acting on the object (acceleration = 0)
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What are Thinking, Breaking and Stopping distances?
(Thinking) distance traveled in the time it takes the driver to react; (Braking) distance traveled between when brakes are applied and when the vehicle stops; (stopping) breaking distance + thinking distance
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What is Hooke's law?
(Springs) Extension is proportional to force applied if elastic limit is not exceeded
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What is elastic limit?
Max. stress that can be applied without deformation
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What is Yield point?
A point where a noticeable change in length occurs due to a force
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What is breaking stress?
Max. stress a material can hold without breaking
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What is brittleness?
When a material can't extend without breaking (good for constant compression/force)
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What is a transverse wave?
A wave that has oscillations perpendicular to the direction of travel to the wave (think of a sine graph)
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What is a longitudinal wave?
A wave where the oscillations are in the same direction as travel of the wave
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What does the term 'in-phase' mean?
When 2 points are an integer number of wavelengths apart (oscillations are in time with each other)
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What is meant by the term 'anti-phase'?
When 2 points are 1/2 a wavelength apart
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What is polarisation?
When oscillations of the electric field of an EM wave are restricted to one plane/direction
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What is the principle of superposition?
The resultant displacement caused by 2 waves arriving at the same point is the vector sum of the 2 displacements caused by the waves at that instant
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What is a stationary wave?
A fixed pattern of vibration where no energy is transferred along the wave
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When are stationary waves formed?
When 2 continuous waves (of the same frequency) travel in opposite directions and superimpose
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On a stationary wave, what is a node?
A particle or point with no displacement/no amplitude
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What is the opposite of a node (and a definition)?
An anti-node (a particle/point with maximum displacement/amplitude)
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Name the album to feature refraction of light in a prism as the cover, and also the colour than 'bends' the least in refraction of visible light though a prism
Dark Side of the Moon (Pink Floyd) and red
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What is the refractive index of a vacuum?
1.00 (one)
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When does Total Internal Reflection occur (2 points please)?
(1) When the incidence substance has a higher r.i. than the other substance (2) when the angle of incidence is greater than the critical angle
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What pattern does the Young's double slit experiment produce?
A zebra crossing pattern - alternate light and dark spots
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In terms of diffraction, what happens if the slit is made narrower?
A larger diffraction effect/ pattern spreads out
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## Other cards in this set

### Card 2

#### Front

Name a scalar quantity

#### Back

Any of the following (or other as appropriate): distance, speed, mass, length, volume, density, area, pressure, power, energy, temperature

### Card 3

#### Front

Name a vector quantity

### Card 4

#### Front

State conditions for equlibrium

### Card 5

#### Front

What is the definition of a moment?