Terence Pang

# Commonly asked A Level Physics Question on Circular Motion - based on YIJC Tutorial Question 4

Updated: Jan 30

If you're having issues solving A level Physics circular motion questions, then watching this video may be good for you. Learn the proper strategies and excel better in your studies.

In this video, we analyse a question on circular motion that can be commonly seen in many school papers and A level exams.

The challenge to circular motion problems is that it involves a multitude of concepts and applying them in several steps in order to arrive at the answer.

## Step-by-Step video to Show How Circular Motion Questions can be Solved

Below is a video where we work on a circular motion question very commonly found in many test papers. The strategy would be to:

Draw a free body diagram

Resolve forces in vertical and horizontal direction using the laws of trigonometry and vector resolution

Apply newton's 2nd law when resolving the forces - taking note that the horizontal component involves the centripetal force so we will need to use the centripetal force formula. There are 2 formula for centripetal force so we will use the one that has the angular speed term in it.

Watch the video for a detailed step-by-step solution.

## Background to A Level Physics - Circular Motion

Circular motion is a fundamental concept in A Level Physics, particularly as outlined by the Singapore Examinations and Assessment Board (SEAB)__ syllabus__. Here's an overview that might be helpful, focusing on key aspects that are typically included in the A Level curriculum.

### 1. **Basic Concepts of Circular Motion**

**Definition**: Circular motion refers to the movement of an object along the circumference of a circle at a constant speed.**Velocity**: The object has a constantly changing velocity due to its direction changing at every point, even if the speed remains constant.**Centripetal Force**: This is the net force causing the circular motion, directed towards the center of the circle.

### 2. **Mathematical Formulation**

**Centripetal Acceleration**: a=v^2/r where v is the velocity and r is the radius of the circular path.**Centripetal Force**: Fc=ma = mv^2/r = mrw^2, where m is the mass of the object and w is the angular velocity

### 3. **Examples of Circular Motion in Everyday Life**

Planetary orbits.

Artificial satellites orbiting the Earth.

Vehicles turning around a curve.

### 4. **Newton's Laws and Circular Motion**

**First Law**: The tendency of objects to maintain their state of motion (inertia) plays a crucial role in understanding why centripetal force is necessary.**Second Law**: The centripetal force is the result of the acceleration towards the center of the circle.

### 5. **Applications in Problem Solving**

Students are often asked to solve problems involving calculating the centripetal force, the velocity of an object in circular motion, or the period of rotation.

Real-world problems may include calculating the forces acting on a vehicle on a curved track or the tension in a string of a pendulum.

### 6. **Common Misconceptions**

One common misconception is that centrifugal force (an apparent force observed in a rotating reference frame) is the same as centripetal force.

The misconception that an object in circular motion has constant velocity due to constant speed, neglecting the vector nature of velocity.

### 7. **Integration with Other Topics**

Linking circular motion to topics like gravitation, energy, and momentum.

Demonstrating how circular motion principles are foundational in understanding complex systems in astrophysics and engineering.

### 8. **Assessment and Evaluation**

Typical assessments involve quantitative problems, conceptual questions, and practical experiments.

The emphasis is on applying theoretical knowledge to practical situations and problem-solving skills.

The SEAB A Level Physics syllabus aims to provide students with a comprehensive understanding of circular motion, blending theoretical knowledge with practical applications.

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