Echoes Within

 Circular Motion (For MCQ Practice)

Here is a clear and exam-focused Summary Note of the lesson, Circular Motion, specifically tailored for MCQ preparation:

🔹 1. What is Circular Motion?

• Circular motion is the motion of an object along a circular path.

• The direction of the object continuously changes, so even at constant speed, its velocity changes (because velocity is a vector).

🔹 2. Types of Circular Motion

1. Uniform Circular Motion (UCM):

   • Speed remains constant

   • Velocity continuously changes due to a direction change

   • Centripetal force acts towards the centre

2. Non-uniform Circular Motion:

   • Speed changes

   • Both the magnitude and direction of velocity change

   • Requires centripetal and tangential force

🔹 3. Important Terms & Formulas

🔹 4. Centripetal Force

• The force that acts towards the centre of the circle

• Responsible for changing the direction of velocity

• Examples:

  • Tension in the string (for a rotating stone)

  • Gravitational force (for planets orbiting the sun)

  • Friction (for a car on a circular track)

🔹 5. Characteristics of UCM

• Speed is constant

• Velocity changes due to a direction change

• Acceleration is always towards the centre (centripetal)

• Centripetal force is essential to keep an object in a circle

• No work is done by the centripetal force (force ⊥ displacement)

🧠 MCQ Focus Areas

• The distinction between uniform and non-uniform circular motion

• Concept of centripetal force and its direction

• Formulas for speed, frequency, time period, force, and acceleration

• Real-life examples of circular motion

• Conceptual questions about the direction of velocity, force, and acceleration

Circular Motion: MCQ Practice Set

🧠 MCQ Quiz Hints

Q1. In uniform circular motion, acceleration is always directed outward from the centre.
✅ Correct Answer:❌ False (It is directed towards the centre.)

Q2. Angular velocity changes with time in uniform circular motion.
✅ Correct Answer:❌ False (Angular velocity is constant.)

Q3. A particle moves in a circle of radius 4 m with a constant speed of 6 m/s. What is the magnitude of its acceleration?

Soln:

 a = v²/r = (6²)/4 = 36/4 = 9 m/s²

Hence, the magnitude of its acceleration is 9 m/s².

Q4. A 2 kg mass is attached to a string of length 1.5 m and whirled in a horizontal circle at 4 m/s. What is the tension in the string?

Soln:

 T = mv²/r = (2 × 16)/1.5 = 32 / 1.5 = 21.3 N

Hence, tension in the string is 21.3 N.

Q5. An object moves with constant speed in a circular path. What is the work done by the centripetal force in one complete revolution?

✅ Correct Answer: Zero
Reason: Centripetal force is perpendicular to displacement; no work is done.

Q6. A conical pendulum has a length of 1 m and completes one revolution in 2 seconds. What is the angular velocity (ω)?

Soln:

 T = 2 s → ω = 2π/T = 2π/2 = π rad/s

Q7. Which of the following forces is not a real force but an effect observed in rotating frames?

✅ Correct Answer: Centrifugal force- As it is a fictitious force observed in a rotating reference frame.

Q8. If mass is doubled and radius is halved for an object in circular motion with the same speed, the centripetal force becomes:

Soln:

Fc = mv²/r → (2m)v²/(r/2) = 4mv²/r → 4 times increase

Note: Here, some terms starting with angular (like angular velocity, angular acceleration, etc) and a few more terms are taken from the NEB syllabus, i.e. out of grade 10(SEE), just for the entrance examination for NEB, Science.

🔍 You Can Also Read:

🧠 Conceptual MCQs – Work, Energy & Power

🔢 Numerical-Based MCQs – Work, Energy & Power

✅ MCQ Quiz – Chapter: Sources of Energy

🧠 Conceptual MCQs – Sources of Energy

✅ MCQ Quiz: Simple Machine

🔢 Numerical-Based MCQ – Simple Machine

🧠 Conceptual MCQs: Friction

📚 MCQ Quiz: Friction

📚 MCQ Quiz: Motion

🧠 Conceptual & Numerical MCQs: Motion

 Unit and Dimension

📘 Scalar and Vector

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