SATHEE: Units Measurements

Units Measurements

SI Base Units (7 only)
- Length: metre (m)
- Mass: kilogram (kg)
- Time: second (s)
- Electric current: ampere (A)
- Temperature: kelvin (K)
- Luminous intensity: candela (cd)
- Amount of substance: mole (mol)
Derived Hot-Shots
- Force: newton (N) = kg·m·s⁻²
- Energy: joule (J) = N·m
- Power: watt (W) = J·s⁻¹
- Pressure: pascal (Pa) = N·m⁻²
- Frequency: hertz (Hz) = s⁻¹
- Charge: coulomb (C) = A·s

Unit	⇄	SI Unit
1 Å	10⁻¹⁰ m	“Angry Ant = 10 negative ten”
1 micron	10⁻⁶ m	“Micro-soap kills 6 germs”
1 light-year	9.46×10¹⁵ m	“Light-16 sweet”
1 astronomical unit (AU)	1.496×10¹¹ m	“Earth–Sun 150 million km”
1 parsec	3.26 light-year	“Par-sec = tri-sec (3)”
1 tonne	1000 kg	“T for Thousand”
1 carat	200 mg	“Car-200”
1 acre	4047 m²	“4–0–4–7”
1 horsepower	746 W	“Horses 747 fly”

1. Which of the following is NOT an SI base unit?

A) Second B) Mole C) Newton D) Ampere **Ans: C) Newton** (derived)

2. 1 light-year is approximately

A) 9.46×10¹² m B) 9.46×10¹⁵ m C) 3×10⁸ m D) 3.26 pc **Ans: B) 9.46×10¹⁵ m**

3. The unit of power is

A) joule B) newton C) watt D) pascal **Ans: C) watt**

4. 1 horsepower equals

A) 550 W B) 746 W C) 764 W D) 1 kW **Ans: B) 746 W**

5. Which quantity is dimensionless?

A) Velocity B) Strain C) Force D) Energy **Ans: B) Strain**

6. 1 parsec is about

A) 1 AU B) 3.26 ly C) 1 ly D) 9.46×10¹⁵ m **Ans: B) 3.26 ly**

7. The SI unit of pressure is

A) N B) Pa C) J D) W **Ans: B) Pa**

8. 1 tonne equals

A) 100 kg B) 1000 g C) 1000 kg D) 10 quintal **Ans: C) 1000 kg**

9. Which unit uses candela? A) Luminous intensity B) Temperature C) Current D) Amount of substance **Ans: A) Luminous intensity**

10. 1 micron is

A) 10⁻³ m B) 10⁻⁶ m C) 10⁻⁹ m D) 10⁻¹² m **Ans: B) 10⁻⁶ m**