Physics

• Vector quantities are physical quantities that have both magnitude and direction.
• Scalar quantities are physical quantities that have magnitude only.
• All physical quantities consist of a numerical magnitude and a unit.
• SI unit for mass is kilogram (kg).
• SI unit for length is metre (m).
• SI unit for time is second (s).
• SI unit for temperature is kelvin (K).
• SI unit for current is ampere (A).
• SI unit for pressure is pascal (Pa).
• SI unit for energy is joule (J).
• SI unit for power is watt (W).
• nano (n) - 10^-9
• micro (μ) - 10^-6
• milli (m) - 10^-3
• centi (c) - 10^-2
• deci (d) - 10^-1
• kilo (k) - 10^3
• mega (M) - 10^6
• giga (G) - 10^9
• tera (T) - 10^12
• Measuring tape: measuring range is 0 to several m. Accuracy is ± 0.1cm/1mm
• Metre rule: measuring range is 0 to 1m. Accuracy is ± 0.1cm/1mm
• Digital calipers: measuring range is 0 to 15cm. Accuracy is ± 0.001cm/0.01mm
• Digital micrometer screw gauge: measuring range is 0 to 2.5cm. Accuracy is ± 0.0001cm/0.001mm.
• Size of typical atom – 1 x 10^-10 m
• Size of the earth – 1.3 x 10^7 m
• Period of a pendulum is the time taken to make one complete oscillation.
• Speed is the rate of change of distance. (v=d/t, unit: m/s)
• Velocity is the rate of change of displacement. (v=s/t, unit: m/s)
• Acceleration is the rate of change of velocity. (a= (v-u)/t, unit: m/s^2)
• Displacement-time graphs: the gradient of the displacement-time graph gives the velocity of the object.
• Velocity -time graphs: the gradient of the velocity-time graph gives the acceleration of the object.
• Area under the velocity-time graph (or area bounded by the graph and the time axis) gives the distance travelled.
• Graphical analysis of velocity

  A)

  
• The acceleration of free fall for a body near to the Earth is constant and is approximately 10 m/s^2
• A body with constant weight falls with acceleration = 10 m/s

  When there is air resistance the body will fall, decreasing acceleration until the weight equals air resistance.

  During this time a = 0 m/s^2 and the body falls with constant speed. This is the maximum speed attained by the body. This speed is called the terminal velocity of the body.