physics

    Subdecks (1)

    Cards (201)

    • Systematic errors
      The reading is larger or smaller than (or varying from) the true reading by a constant amount
    • Random errors
      Scatter in readings about the true reading
    • Precision
      The size of the smallest division (on the measuring instrument) or 0.01 mm for the micrometer
    • Accuracy
      How close (diameter) value is to the true (diameter) value
    • Instruments used to measure

      • Length: metre rule/tape
      • Diameter: micrometer (screw gauge) / digital caliper
      • Resistance: ammeter and voltmeter/ohmmeter/multimeter on 'ohm' setting
    • Experimental measurements that are more accurate will have the peak/average value move towards the true value
    • Experimental measurements that are more precise will have lines that are closer together/sharper peak
    • Systematic errors
      e.g. constant error (in all readings), cannot be eliminated by averaging, error in measuring instrument
    • Random errors
      e.g. readings scattered (equally) about true value, error due to observer, can be eliminated by averaging
    • Ways to reduce systematic error in micrometer readings

      • Check for zero error (on micrometer)/zero the micrometer
    • Acceleration
      Change in velocity/time (taken) or rate of change of velocity
    • Speed
      Distance/time and has no direction
    • Velocity
      Displacement/time and has magnitude and direction
    • Distance
      Sum of lengths moved
    • Displacement
      Straight line between two points and is a vector
    • Scalar quantity

      Has magnitude only
    • Vector quantity
      Has magnitude and direction
    • Mass
      Property of a body resisting changes in motion/quantity of matter in a body/measure of inertia to changes in motion
    • Weight
      Force due to the gravitational field/force due to gravity
    • Situations where mass is constant but weight changes

      • Change in gravitational field strength
      • Change in fluid surrounding body
    • Newton's second law

      (Resultant) force proportional/equal to rate of change of momentum
    • Conservation of momentum

      Total momentum of a system (of colliding particles) remains constant provided there is no resultant external force acting on the system/ isolated or closed system
    • Newton's first law
      A body/mass/object continues (at rest or) at constant / uniform velocity unless acted on by a resultant force
    • Momentum
      Mass x velocity
    • Kinetic energy
      Momentum^2 / 2 x mass
    • Pressure
      Force/area (normal to force)
    • Deriving pressure due to liquid

      1. Use of m=pV and use of V=Ah and use of F=mg
      2. Correct substitution to obtain p=pgh
    • Explaining pressure exerted by gases
      1. Molecules/atoms/particles in (constant) random/haphazard motion
      2. Molecules have a change in momentum when they collide with the walls
      3. Force exerted on molecules therefore force on the walls
      4. Reference to average force from many molecules/many collisions
    • Pressure at top of mountain
      • Fewer molecules per unit volume
      • Temperature is less
      • Hence lower speed of molecules
      • Hence less pressure
    • Deriving pressure exerted by liquid on base
      1. Pressure=Force/Area
      2. Weight (of liquid)/Force (on base) = Ahpg
      3. Pressure=hpg
    • Frequency of a progressive wave
      • Number of oscillations per unit time of the source/of a point on the wave/of a particle (in the medium)
      • Number of wavelengths/wavefronts per unit time passing a (fixed) point
    • Loudspeaker moving towards observer causes rise in/higher frequency, loudspeaker moving away from observer causes fall in/lower frequency
    • Diffraction of a wave
      • Wave incident on/passes by or through an aperture/edge
      • Wave spreads (into geometrical shadow)
    • Longitudinal wave

      Vibrations/oscillations (of the particles/wave) are parallel to the direction or in the same direction (of the propagation of energy)
    • Transverse wave

      Vibrations/oscillations (of the particles/wave) are perpendicular to the direction (of the propagation of energy)
    • Doppler effect
      Change/difference in the observed/apparent frequency when the source is moving (relative to the observer)
    • When a distant star is moving away from a stationary observer, the wavelength increases/frequency decreases/red shift
    • Adjustments to produce stationary waves on a stretched string
      • Alter distance from vibrator to pulley
      • Alter frequency of generator
      • Change tension in string by changing value of the masses
    • Diffraction
      Spreading/diverging of waves/light (takes place) at (each) slit/element/gap/aperture
    • Interference
      Overlapping of waves (from coherent sources at each element)
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