Physics Numerical of Class 9 Chapter 1

Introduction:
Class 9 Physics introduces students to the basic concepts and principles of the subject. Chapter 1 focuses on the fundamental concepts of motion, force, and laws of motion. In this chapter, students learn about different types of motion, how to calculate speed, velocity, and acceleration, and the laws of motion proposed by Sir Isaac Newton.

Numerical 1: Calculation of Speed
Let's consider a numerical example to understand the calculation of speed:
Question: A car travels a distance of 400 meters in 20 seconds. Calculate its speed.
Solution:
Given:
Distance (d) = 400 meters
Time (t) = 20 seconds

The formula to calculate speed is:
Speed (v) = Distance (d) / Time (t)

Substituting the values:
v = 400 meters / 20 seconds
v = 20 meters/second

Therefore, the speed of the car is 20 meters/second.

Numerical 2: Calculation of Velocity
Let's consider another numerical example to understand the calculation of velocity:
Question: A car travels a distance of 600 meters towards the east in 30 seconds. Calculate its velocity.
Solution:
Given:
Distance (d) = 600 meters
Time (t) = 30 seconds
Direction = East

The formula to calculate velocity is:
Velocity (v) = Displacement (d) / Time (t)

In this case, since the question mentions the direction, we need to consider displacement instead of distance. Displacement is the change in position and involves both distance and direction.

Substituting the values:
v = 600 meters (East) / 30 seconds
v = 20 meters/second (East)

Therefore, the velocity of the car is 20 meters/second towards the east.

Numerical 3: Calculation of Acceleration
Let's consider one more numerical example to understand the calculation of acceleration:
Question: A car accelerates from rest to a velocity of 30 m/s in 10 seconds. Calculate its acceleration.
Solution:
Given:
Initial velocity (u) = 0 m/s (as the car starts from rest)
Final velocity (v) = 30 m/s
Time (t) = 10 seconds

The formula to calculate acceleration is:
Acceleration (a) = (Final velocity (v) - Initial velocity (u)) / Time (t)

Substituting the values:
a = (30 m/s - 0 m/s) / 10 seconds
a = 3 m/s²

Therefore, the acceleration of the car is 3 m/s².

Conclusion:
In this chapter, students learn to calculate speed, velocity, and acceleration using the respective formulas. These numerical examples provide a practical understanding of the concepts and help students apply the formulas to solve problems related to motion. Practicing these numericals will strengthen their understanding and proficiency in physics.