1.1 - PHYSICAL QUANTITIES & MEASUREMENT TECHNIQUES

• A physical quantity is a quantity that can be measured and consists of a numerical magnitude (value) and a unit.
• Base Quantity:

  • Length (l) (metres, m)
  • Time (t) (seconds, s)
  • Mass (m) (kilograms, kg)
  • Temperature (T) (kelvin, K)
  • Electric Current (I) (ampere/s, A)
• Prefixes are used to express physical quantities that have very large or very small values.

  
• • Measuring Tape (0.1 cm)
  • Metre Ruler (0.1 cm)
  • Half-metre Ruler (0.1 cm)
  • Micrometre Screw Gauge (0.01 mm)
• Parallax Errors are caused by the inaccurate positioning of the observer's eye while taking readings. To avoid this error, the eye should be positioned directly above the marking or scale.
• Zero Error is a non-zero reading measure when we expect a zero reading. Unlike Parallax Error, accurate reading can still be taken using these measuring instruments by subtracting the zero error from the measured reading.
• Micrometer Screw Gauge Formula: Measured reading = main scale reading + thimble scale reading
• Normally, we measure volume of a liquid in a measuring cylinder.
• How to find volume of a regular solid (cubic unit)

  • Square - l x l x l
  • Rectangle - l x b x h
  • Cylinder - Pi(rx r) (h)
• Period is the time taken for the pendulum to make one complete oscillation. (Symbol: T)
• Steps to success on calculations:

  • Write Formula
  • Substitute the formula according to the values in the question and solve with the appropriate working.
  • Write final answer with appropriate value and unit. (3 significant figures)
• Scalars are quantities that includes magnitude ONLY.

  Vectors are quantities that include both magnitude AND direction.
• How To Calculate Non-Parallel Vectors

  (Paper 1) - Phythagoras' Theorem

  (Paper 2)

  1. Choose Suitable scale
  2. Redraw the vectors with the scale
  3. Measure the resultant force
  4. Solve by Cross multiply with the scale
  5. Find angle to explain direction (use protactor)