In this post, we’ll talk about some Common O-Level Physics Mistakes.

Here are some questions that O-level students get wrong (Part 1).
Kinetic and Potential Energy


Common Misconception: Sometimes students think that an object can have only one type of energy at a time, but an object can have both kinetic and gravitational potential energy at once.
Kinetic Energy (KE): The energy an object has due to its motion. The formula is: KE = 1/2mv²
where m is the mass and v is the velocity of the object.
Potential Energy (PE): The energy stored in an object due to its position. For gravitational potential energy, the formula is: 𝑃𝐸 = 𝑚𝑔ℎ
where m is the mass, g is the gravitational acceleration, and h is the height above the ground.
Tip:
1. An object moving on the ground has only kinetic energy.
2. An object at rest at a height has only gravitational potential energy.
3. An object moving at a height has both kinetic and gravitational potential energy.
Conservation of Energy

Common Misconception: Students may think energy can be lost or gained, but energy can only change forms—it cannot be created or destroyed.
In a closed system, total energy stays the same. For example, in a pendulum, the potential energy at the highest point is converted to kinetic energy as it reaches the lowest point.
Ohm’s Law and Electrical Circuits

Common Misconception: Students often mix up current (I), voltage (V), and resistance (R).
Ohm’s Law: 𝑉 = 𝐼𝑅
where V is the voltage, I is the current, and R is the resistance.
Tip: Recognize units:
Current is measured in Amperes (A),
Voltage in Volts (V), and
Power in Watts (W).
Wave Properties

Common Misconception: Students sometimes confuse wavelength, frequency, and wave speed.
Wave Speed (v): v = fλ
where f is the frequency and λ (lambda) is the wavelength.
Tip: Use the wave equation to relate these quantities. Remember, a higher frequency means a shorter wavelength.
Newton’s Laws of Motion

Common Misconception: Students sometimes misunderstand how Newton’s Second Law works.
Newton’s Second Law: 𝐹 = 𝑚𝑎
where F is the net force, m is the mass, and a is the acceleration.
Tip: If an object is moving at a constant velocity, it does not mean there’s no forward or engine force. Instead, it means there’s zero acceleration, so the net force is zero. This means the forward force is balanced by the backward force (like friction or air resistance).
Done!
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