EmSAT Physics 2 ā Questions and Answers
Question 1: What is the potential energy of a 5 kg object at a height of 10 meters? (g = 10 m/sĀ²)
- 50 J
- 500 J (Correct answer)
- 100 J
- 250 J
Correct answer: 500 J
Gravitational potential energy = mgh = 5 kg Ć 10 m/sĀ² Ć 10 m = 500 J.
Question 2: Which law of thermodynamics states that energy cannot be created or destroyed?
- Zeroth Law
- First Law (Correct answer)
- Second Law
- Third Law
Correct answer: First Law
The First Law of Thermodynamics (Law of Conservation of Energy) states that energy cannot be created or destroyed, only transformed from one form to another.
Question 3: What happens to the current in a circuit if the resistance is tripled and voltage remains constant?
- Current triples
- Current is reduced to one-third (Correct answer)
- Current remains the same
- Current is reduced to one-ninth
Correct answer: Current is reduced to one-third
By Ohm's Law (V = IR), if V is constant and R triples, then I = V/R becomes V/(3R), which is one-third of the original current.
Question 4: What is the net force on an object moving at constant velocity?
- Equal to its weight
- Zero (Correct answer)
- Equal to the applied force
- Equal to friction force
Correct answer: Zero
According to Newton's First Law, an object moving at constant velocity has zero net force acting on it ā all forces are balanced.
Question 5: What is the focal length of a converging lens if an object at 30 cm produces an image at 15 cm?
- 45 cm
- 10 cm (Correct answer)
- 15 cm
- 20 cm
Correct answer: 10 cm
Using the thin lens equation: 1/f = 1/v + 1/u = 1/15 + 1/30 = 2/30 + 1/30 = 3/30 = 1/10, so f = 10 cm.
Question 6: Which electromagnetic wave has the highest frequency?
- Radio waves
- Infrared
- Visible light
- Gamma rays (Correct answer)
Correct answer: Gamma rays
In the electromagnetic spectrum, gamma rays have the highest frequency (and shortest wavelength), followed by X-rays, UV, visible light, infrared, microwaves, and radio waves.
EmSAT Physics 2
What is the potential energy of a 5 kg object at a height of 10 meters? (g = 10 m/sĀ²)