MEASUREMENTS

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• Q1: Define Mechanics.
  Ans: Mechanics is the branch of physics that deals with the study of forces and motion of bodies.
• Q2: Define Applied Mechanics.
  Ans: Applied mechanics is the practical application of mechanics to solve engineering problems.
• Q3: Define Units.
  Ans: Units are standard quantities used to measure physical quantities.
• Q4: Define Derived Units. Name some.
  Ans: Derived units are units obtained from fundamental units.
  Examples are:

  • ➔ Velocity (m/s)
  • ➔ Force (N)
  • ➔ Work (J)
  • ➔ Pressure (Pa)
• Q5: Define Fundamental Units. Name some.
  Ans: Fundamental units are basic units that cannot be derived from other units.
  Examples are:

  • ➔ Meter (m)
  • ➔ Kilogram (kg)
  • ➔ Second (s)
• Q6: Define Basic Units. Name some.
  Ans: Basic units are same as fundamental units used to measure basic physical quantities.
  Examples are:

  • ➔ Length (meter)
  • ➔ Mass (kilogram)
  • ➔ Time (second)
• Q7: Define measurement.
  Ans: Measurement is the process of comparing an unknown quantity with a standard unit.
• Q8: State the units of measurements.
  Ans: Units of measurement include:

  • ➔ Length → meter (m)
  • ➔ Mass → kilogram (kg)
  • ➔ Time → second (s)
• Q9: What is the M.K.S system?
  Ans: M.K.S system uses meter, kilogram, and second as base units.
• Q10: What is the F.P.S system?
  Ans: F.P.S system uses foot, pound, and second as base units.
• Q11: What is the C.G.S system?
  Ans: C.G.S system uses centimeter, gram, and second as base units.
• Q12: What is the S.I system?
  Ans: S.I system is the international system of units used worldwide.
  It includes meter, kilogram, and second as basic units.
• Q13: Convert 2 Miles into Meters.
  Ans: 1 mile = 1609 m
  
  2 miles = 2 × 1609 = 3218 m
  
  Final Answer:
  2 miles = 3218 m
• Q14: Convert 500 ft into inches.
  Ans: 1 ft = 12 inches
  
  500 ft = 500 × 12 = 6000 inches
  
  Final Answer:
  6000 inches
• Q15: The speed of a cycle is 4ft/s. Find the speed in m/s
  Ans: 1 ft = 0.3048 m
  
  Speed = 4 × 0.3048 = 1.219 m/s
  
  Final Answer:
  1.22 m/s
• Q16: Define velocity. Write its formula.
  Ans: Velocity is the rate of change of displacement with time and has direction.
  
  Formula:
  
  Velocity = Displacement / Time
• Q17: Define Density. Write its formula.
  Ans: Density is the mass per unit volume of a substance.
  
  Formula:
  
  Density = Mass / Volume
• Q18: What is Dimensional Equation?
  Ans: A dimensional equation shows the relationship between physical quantities in terms of fundamental units like M, L, and T.
• Q19: State the uses of Dimensional Equations.
  Ans: Uses are:

  • ➔ To check correctness of equations
  • ➔ To convert units
  • ➔ To derive formulas
• Q20: Express a speed of 50km/hr as m/s.
  Ans: 1 km/hr = 5/18 m/s
  
  50 × (5/18) = 250/18 = 13.89 m/s
  
  Final Answer:
  13.89 m/s
• Q21: Define Significant Figures. State some examples.
  Ans: Significant figures are digits in a number that carry meaningful information about precision.
  
  Examples:

  • ➔ 25.3 (3 significant figures)
  • ➔ 0.0045 (2 significant figures)
  • ➔ 100.5 (4 significant figures)
• Q22: State the rules for identifying significant figures.
  Ans: Rules are:

  • ➔ All non-zero digits are significant
  • ➔ Zeros between digits are significant
  • ➔ Leading zeros are not significant
  • ➔ Trailing zeros after decimal are significant
• Q23: State the difference between Precision and Accuracy.
  Ans: Precision means how close repeated values are to each other.
  Accuracy means how close a value is to the true value.
• Q24: Define Relative Error.
  Ans: Relative error is the ratio of absolute error to true value.
  Formula:
  
  Relative Error = Absolute Error / True Value
• Q25: Prove that 1N = 10⁵ dyne.
  Ans: 1 N = 1 kg·m/s²
  1 kg = 1000 g
  1 m = 100 cm
  
  So,
  1 N = 1000 × 100 g·cm/s²
  1 N = 100000 dyne = 10⁵ dyne
• Q26: Convert 5 Horse Power into Watt.
  Ans: 1 HP = 746 W
  
  5 × 746 = 3730 W
  
  Final Answer:
  3730 W
• Q27: The density of water is 1g/cm3. express it in kg/m3.
  Ans: 1 g = 0.001 kg
  1 cm³ = 10^-6 m³
  
  Density = 0.001 / 10^-6 = 1000 kg/m³
  
  Final Answer:
  1000 kg/m³
• Q28: Convert 5 hours 30 minutes into seconds.
  Ans: 5 hours = 5 × 3600 = 18000 s
  30 minutes = 30 × 60 = 1800 s
  
  Total = 18000 + 1800 = 19800 s
  
  Final Answer:
  19800 seconds
• Q29: The height of the student is 5ft 9inches. Convert it into meters.
  Ans: 1 ft = 0.3048 m
  1 inch = 0.0254 m
  
  5 ft = 5 × 0.3048 = 1.524 m
  9 inch = 9 × 0.0254 = 0.2286 m
  
  Total height = 1.524 + 0.2286 = 1.7526 m
  
  Final Answer:
  1.75 m
• Q30: What is the density of water?
  Ans: The density of water is:
  1000 kg/m³ or 1 g/cm³