Polytechnic Physics 1 — Questions and Answers
Question 1: What is the speed of light in a vacuum?
- 3 × 10⁸ m/s (Correct answer)
- 3 × 10⁶ m/s
- 3 × 10¹⁰ m/s
- 3 × 10⁴ m/s
Correct answer: 3 × 10⁸ m/s
The speed of light in a vacuum is approximately 3 × 10⁸ meters per second (299,792,458 m/s exactly).
Question 2: Which law describes the gravitational force between two masses?
- Newton's Law of Universal Gravitation (Correct answer)
- Coulomb's Law
- Hooke's Law
- Faraday's Law
Correct answer: Newton's Law of Universal Gravitation
Newton's Law of Universal Gravitation states that the force between two masses is proportional to their masses and inversely proportional to the square of the distance between them.
Question 3: What is the unit of frequency?
- Hertz (Hz) (Correct answer)
- Newton (N)
- Joule (J)
- Kelvin (K)
Correct answer: Hertz (Hz)
Frequency is measured in hertz (Hz), where 1 Hz equals one cycle per second.
Question 4: What type of wave is sound?
- Longitudinal wave (Correct answer)
- Transverse wave
- Electromagnetic wave
- Standing wave
Correct answer: Longitudinal wave
Sound is a longitudinal wave where the medium (air) vibrates parallel to the direction of wave propagation.
Question 5: What happens to the wavelength of light as its frequency increases?
- Wavelength decreases (Correct answer)
- Wavelength increases
- Wavelength stays the same
- Wavelength doubles
Correct answer: Wavelength decreases
Since the speed of light is constant, wavelength and frequency are inversely related: λ = c/f.
Question 6: What is the principle of conservation of momentum?
- Total momentum of a closed system remains constant unless acted on by an external force (Correct answer)
- Momentum is always zero in an isolated system
- Momentum increases with velocity
- Momentum and energy are always equal
Correct answer: Total momentum of a closed system remains constant unless acted on by an external force
In a closed system with no external forces, the total momentum before and after a collision remains the same.
Polytechnic Physics 1
What is the speed of light in a vacuum?