Unit 4: Turning Effects of Force - Numerical Problems

Class 9 Physics Notes | Unit 4 – Turning Effects of Force | Class 9 Physics (New Syllabus)

📘 Solved Numerical Problems (Turning Effects of Force)

Related Resources:

Introduction to Numerical Problems

Numerical problems in Turning Effects of Force help students apply theoretical concepts to practical situations, developing problem-solving skills essential for understanding rotational dynamics.

This section contains solved numerical problems covering all major topics from Chapter 4: Turning Effects of Force. Each problem includes:

Problem-Solving Approach

When solving turning effects problems, follow these steps:

  1. Read the problem carefully and identify what is being asked
  2. List all given quantities with proper units
  3. Identify the relevant physics principles and formulas
  4. Set up the equations based on the identified principles
  5. Solve the equations step by step
  6. Include proper units in your final answer
  7. Check if your answer makes physical sense

Topics Covered

The numerical problems in this chapter cover:

Working through these problems will strengthen your understanding of rotational dynamics and prepare you for exams and practical applications of physics concepts.

Important Formulas

Key formulas used in solving turning effects problems:

Resultant Force

\[F = \sqrt{(F_x)^2 + (F_y)^2}\]

Angle of Resultant Force

\[\theta = \tan^{-1} \left( \frac{F_y}{F_x} \right)\]

X-Component of Force

\[F_x = F \cos \theta\]

Y-Component of Force

\[F_y = F \sin \theta\]

Torque

\[\tau = r \times F\] \[\tau = rF \sin \theta\]

First Condition of Equilibrium

\[\sum F = 0\]

Second Condition of Equilibrium

\[\sum \tau = 0\]

Principle of Moments

\[\text{Clockwise moments} = \text{Anticlockwise moments}\]

Weight

\[w = mg\]

Problem Types Overview

1. Force Resolution Problems

These problems involve breaking down a single force into its perpendicular components (x and y components). This is essential for analyzing forces acting at angles.

2. Torque Calculation Problems

These problems focus on calculating the turning effect of forces, considering both the magnitude of force and its perpendicular distance from the pivot point.

3. Principle of Moments Problems

These problems apply the principle that for a body in equilibrium, the sum of clockwise moments equals the sum of anticlockwise moments about any point.

4. Equilibrium Problems

These problems involve applying both conditions of equilibrium (sum of forces = 0 and sum of torques = 0) to solve for unknown forces or distances.

5. Tension Problems

These problems calculate tension in strings or ropes when objects are suspended or pulled at angles, requiring force resolution and equilibrium conditions.

Created by Hira Science Academy | Aligned with PECTA 2025 Syllabus

← Back to Class 9 Physics Notes