Polytechnic Physics 2 — Questions and Answers
Question 1: What is the formula for gravitational potential energy?
- PE = mgh (Correct answer)
- PE = ½mv²
- PE = mc²
- PE = Fd
Correct answer: PE = mgh
Gravitational potential energy is PE = mgh, where m is mass, g is gravitational acceleration, and h is height.
Question 2: What is absolute zero on the Kelvin scale?
- 0 K (Correct answer)
- -273.15 K
- 273.15 K
- 100 K
Correct answer: 0 K
Absolute zero is 0 K, which corresponds to -273.15°C, the theoretical lowest possible temperature.
Question 3: What phenomenon describes the bending of light as it passes through a lens?
- Refraction (Correct answer)
- Reflection
- Diffraction
- Interference
Correct answer: Refraction
Refraction is the bending of light as it passes through a medium of different optical density, as in a lens.
Question 4: What is the formula for work done by a constant force?
- W = F × d × cos(θ) (Correct answer)
- W = F × d
- W = F / d
- W = F + d
Correct answer: W = F × d × cos(θ)
Work equals force times displacement times the cosine of the angle between them: W = Fd·cos(θ).
Question 5: What does the photoelectric effect demonstrate?
- Light behaves as particles (photons) (Correct answer)
- Light travels in straight lines
- Light has no mass
- Light is a mechanical wave
Correct answer: Light behaves as particles (photons)
The photoelectric effect shows that light ejects electrons from a metal surface only when its frequency exceeds a threshold, proving light's particle nature.
Question 6: What is electric potential difference also known as?
- Voltage (Correct answer)
- Current
- Resistance
- Power
Correct answer: Voltage
Electric potential difference is commonly called voltage, measured in volts (V).
Polytechnic Physics 2
What is the formula for gravitational potential energy?