Flashcards
Unit 2: Mechanics, Materials and Waves
Cards in this deck (44)
- 1Define: scalar and vector quantitiesScalar: magnitude only
Vector: magnitude and direction - 2Give an example of a scalar and a vector quantityScalar: distance, speed, mass
Vector: displacement, velocity, weight - 3Define: displacementStraight line distance between two points
- 4Define: speedRate of change of distance
- 5Define: velocityRate of change of distance
- 6Define: accelerationRate of change of velocity
- 7Define: equilibriumResultant moment = zero
Resultant force = zero - 8Define: momentProduct of force and perpendicular distance to the pivot
- 9Define: principle of momentsIn equilibrium, total anticlockwise moments = total clockwise moments about a point
- 10Define: coupleTwo equal and opposite forces acting along parallel lines of action
Couple = force x shortest distance between their lines of action - 11Define: centre of massThe point where all the mass of an object can be considered to act
- 12Define: centre of gravityThe point where all the weight of an object can considered to act
- 13What does the gradient of a displacement-time graph represent?speed
- 14What does the gradient of a velocity-time graph represent?acceleration
- 15What does the area under a velocity-time graph represent?displacement
- 16Why can horizontal motion and vertical motion be treated independently?They act at 90 degrees to each other
or
Horizontal motion is constant and vertical motion involves acceleration - 17State Newton's 1st lawObjects remain at rest or constant velocity unless external forces act
- 18State Newton's 2nd LawAcceleration is proportional to
resultant force
(F = ma) - 19State Newton's 3rd LawFor every action there is an equal and opposite reaction
- 20Describe one situation where Newton's 1st law appliesConstant velocity so no friction or air resistance would occur in space
or
another situation where friction is negligible e.g. linear air track - 21Describe how the forces acting on a falling object change as it fallsInitially, weight is greater than air resistance. As speed increases, air resistance increases, until air resistance = weight, so no resultant force and no acceleration
- 22What is meant by conservation of energy?Energy is neither created nor destroyed only changed from one form to another
- 23Define: densityThe ratio of an objects mass to its volume
- 24Define: tensile stressThe force per unit area of cross-section
- 25Define: tensile strainExtension per unit length
- 26State Hooke's LawExtension of a material (or spring) is directly proportional to the applied force, up to the limit of proportionality
- 27What is meant by 'elastic limit'?The point beyond which the material will not return to its original size and shape
- 28Define: Young ModulusThe ratio of tensile stress to tensile strain
- 29What does the area under a stress vs. strain graph represent?Energy stored per unit volume
- 30What does the area under a force vs. extension graph represent?Energy stored
- 31What does the gradient of a stress vs. strain graph represent?Young Modulus
- 32Which equation starts the derivation for the energy stored in a stretched material?Work = Force x displacement
- 33Define: Breaking StressThe breaking force per unit area of a material
- 34Define: progressive waveThe movement of a disturbance from a source, which transfers energy and momentum from the source to places around it
- 35Define: stationary waveStationary or standing waves result from the superposition of two progressive waves with same frequency and amplitude
- 36Define: Transverse waveParticles in the path of the wave oscillate at 90 degrees to the direction of wave propagation
- 37Define: Longitudinal waveParticles in the path of the wave oscillate parallel to the direction of wave propagation
- 38What is the phase difference between particles one wavelength apart on a progressive wave?0, they are in phase
- 39What is the phase difference between particles half a wavelength apart on a stationary wave?antiphase / 180 degrees
- 40What is the phase difference between particles half a wavelength apart on a progressive wave?180 degrees / antiphase
- 41What property of light waves does polarisation demonstrate?They are transverse
- 42If light refracts towards the normal what does this mean for the refractive indices of two materials?Refractive index of material 1 is lower than material 2
- 43If light refracts away from the normal what does this mean for the refractive indices of two materials?Refractive index of material 1 is higher than material 2
- 44State Snell's Law of RefractionWhen a ray of monochromatic light travels from a less dense material to a more dense material it will bend towards the normal (provided it approaches the boundary at an angle other than 90 degrees)
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- Flashcards on Unit 2: Mechanics, Materials and Waves, created by Michael Priest on 08/05/2015.
- Created by
- Michael Priest · May 2015
- Updated
- Feb 19, 2016
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