Chapter on Motion - Class 9

These flashcards cover key concepts related to motion, definitions of various terms, differences between quantities, and important equations from the lecture.

What is the definition of motion?

An object is said to be in motion when its position changes with time.

What does it mean for an object to be at rest?

A body is said to be in a state of rest when its position does not change with time.

Define relative motion.

A body can be moving for one observer and at rest for another observer.

What is a physical quantity?

A physical quantity is a property of a material or system that can be measured and quantified.

What is the difference between scalar and vector quantities?

Scalar quantities have magnitude only, while vector quantities have both magnitude and direction.

What does distance refer to?

Distance is the actual length of the path travelled by the particle in a given interval of time.

What is displacement?

Displacement is the shortest distance between the initial and final positions of a moving particle in a specific direction.

How is average speed calculated?

Average speed is stated as the total distance covered divided by the total time taken.

What is the formula for velocity?

Velocity is the rate of change of displacement and is calculated by the formula: Velocity = Displacement/Time.

What is acceleration?

Acceleration is the rate of change of velocity with time.

What is the difference between uniform and non-uniform motion?

Uniform motion is when an object covers equal distances in equal intervals of time, whereas non-uniform motion is when the distance covered varies in equal intervals of time.

Define free fall motion.

Free fall motion is when an object moves only under the influence of gravity, resulting in acceleration.

What does the area under a velocity-time graph represent?

The area under a velocity-time graph represents the displacement of the object.

How does uniform circular motion differ from linear motion?

In uniform circular motion, the object moves along a circular path while maintaining a constant speed, but its direction (and hence velocity) changes.

What is the SI unit of speed?

The SI unit of speed is meters per second (m/s).