Explanation

• A parachute increases air resistance (drag) when it opens in the air.
• This slows down the falling speed of a skydiver, allowing a safe landing.

Forces acting on a skydiver:

• Gravity (pulls downward)
• Air resistance (pushes upward)

Last verified on 07-03-2026

Explanation

• An iron nail/steel rod can be magnetized by passing an electric current around it, a process known as electromagnetic induction.
• This is the principle behind electromagnets.

Last verified on 07-03-2026

Explanation

• Friction is a force that opposes motion between two surfaces in contact.
• It slows down or stops objects when they move against each other.
• Friction helps us walk, write, and hold objects without slipping.
• Too much friction can cause heat and wear in machines.

Last verified on 07-03-2026

Explanation

• An eraser is usually made of rubber, which does not attract magnets.
  • Magnetic materials are substances that are attracted by a magnet.
  • Materials like iron and steel are magnetic, while rubber or plastic items are non-magnetic.

Additional information:

• Common Magnetic Materials:
  • Iron
  • Nickel
  • Cobalt
  • Steel (paper clip, iron nail)
  • Some alloys
  Non-magnetic examples: Rubber, wood, plastic, paper.

Last verified on 07-03-2026

Explanation

Mercury is used as a thermometric fluid

Because it has several ideal properties like:

• High Boiling Point (B.P)
• Low Freezing Point (not high M.P)
• Stable and Uniform Coefficient of Expansion
• Visibility and Non-wettability

Last updated on 06-March-2026

Explanation

Explanation

• Resistance (R) measures how much a material opposes the flow of electric current.
• According to Ohm’s Law, V = I × R (Voltage = Current × Resistance).
• Rearranging gives R = V / I (Resistance = Voltage ÷ Current).
• The standard unit of resistance is the ohm (Ω).
• Resistance increases with the length of the conductor and decreases with its cross-sectional area.

Last updated on 06-March-2026

Explanation

• Speed tells how fast an object moves.
• It is calculated by dividing the distance traveled by the time taken.
• Formula: Speed = Distance ÷ Time.
• The standard unit of speed is m/s (meters per second) or km/h.
• Dimensional formula of speed is [M^0 L^1 T^-1] or smply [LT^-1]

Last updated on 06-March-2026

Explanation

Force is defined by Newton’s Second Law:

***

1. Length – [L]  

2. Mass – [M]  

3. Time – [T]  

4. Speed/Velocity – [LT⁻¹]  

5. Acceleration – [LT⁻²]  

6. Force – [MLT⁻²]  

7. Work/Energy – [ML²T⁻²]  

8. Power – [ML²T⁻³]  

9. Pressure – [ML⁻¹T⁻²]  

10. Density – [ML⁻³]  

11. Momentum – [MLT⁻¹]  

12. Impulse – [MLT⁻¹]  

13. Gravitational constant (G) – [M⁻¹L³T⁻²]  

14. Planck’s constant (h) – [ML²T⁻¹]  

15. Charge – [TI] (T = time, I = current)  

16. Potential difference (Voltage) – [ML²T⁻³A⁻¹]  

17. Electric current – [I]  

18. Electric resistance – [ML²T⁻³A⁻²]  

19. Capacitance – [M⁻¹L⁻²T⁴A²]  

20. Magnetic field (B) – [MT⁻²A⁻¹]

Explanation

• Ohm's Law Equation : V = IR
• V is the voltage across the conductor
• I is the current flowing through the conductor
• R is the resistance provided by the conductor to the flow of current.

Last updated on 06-March-2026