Unit 2: Kinematics - Numerical Problems

Class 9 Physics Notes | Unit 2 – Numerical Problems | Class 9 Physics (New Syllabus)

📘 Numerical Problems (Kinematics)

Related Resources:

Introduction to Kinematics Numerical Problems

Kinematics is the branch of mechanics that deals with the motion of objects without considering the forces that cause the motion. Numerical problems in kinematics help us apply theoretical concepts to practical situations.

This section contains carefully selected numerical problems that cover all important concepts of kinematics. Solving these problems will help you:

Each problem is accompanied by a detailed step-by-step solution to help you understand the methodology and approach required to solve similar problems.

Important Formulas for Kinematics

Distance

\[S = v_{av} \times t\]

Where \( S \) is distance, \( v_{av} \) is average speed, and \( t \) is time

Average Acceleration

\[a_{av} = \frac{v_f - v_i}{t}\]

Where \( v_i \) is initial velocity, \( v_f \) is final velocity, and \( t \) is time

First Equation of Motion

\[v_f = v_i + at\]

Relates final velocity with initial velocity, acceleration, and time

Second Equation of Motion

\[S = v_i t + \frac{1}{2} at^2\]

Relates displacement with initial velocity, time, and acceleration

Third Equation of Motion

\[2aS = v_f^2 - v_i^2\]

Relates velocity and displacement without time

Equations of Motion Under Gravity

\[v_f = v_i + gt\] \[h = v_i t + \frac{1}{2} gt^2\] \[2gh = v_f^2 - v_i^2\]

For free fall, \( g \) is positive; for upward motion, \( g \) is negative

Important Conversion Factors:

To convert \( ms^{-1} \) to \( kmh^{-1} \) multiply speed with 3.6

To convert \( kmh^{-1} \) to \( ms^{-1} \) multiply speed with \( \frac{10}{36} \)

Problem Solving Approach

Step 1: Identify Given Data - Carefully read the problem and list all given quantities with their units.

Step 2: Identify Required Quantity - Determine what needs to be found in the problem.

Step 3: Select Appropriate Formula - Choose the kinematic equation that connects the given and required quantities.

Step 4: Unit Conversion - Ensure all quantities are in consistent units (preferably SI units).

Step 5: Substitute and Solve - Plug the values into the formula and solve for the unknown.

Step 6: Check Your Answer - Verify that the answer makes physical sense and has correct units.

Created by Hira Science Academy | Aligned with PECTA 2025 Syllabus

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