# Motion and Time

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## An Introduction To Motion

### Distance

• Distance is the total path covered by the object in the given interval of time.

• Displacement is the shortest path covered by the moving object within the given interval of your time .

• Distance=Speed×Time.

• Unit of distance is usually measured in units of length like metres, kilometres etc.

### Introduction to Motion

• An object is claimed to be in motion if it changes its position with reference to time. Eg: A car moving on a road.

• An object is claimed to be at rest if the thing doesn't change its position with time. Eg: A person standing on the ground.

### Basics of Standard Units

Units and their Standardization

• The standard unit of distance is in metres.

• The standard unit of your time is in seconds (s).

• The standard unit of speed can be measured in metre per second (m/s).

### Basics of Motion and Its Types

Types of Motion

Types of motion are generally divided into parts -

1. Rectilinear / Translatory motion: When a body occupies a line , without changing its direction, then the body is claimed to possess translatory/rectilinear motion. Eg: A car moving on a straight road.

2. Circular Motion: When a body moves within the shape of a circle with a few fixed points and a hard and fast radius, then the body is claimed to be in circular motion. Eg: Motion of planets around the sun.

3. Period / Oscillatory Motion: When the motion of a body repeats after fixed intervals of your time , then the body is claimed to within the periodic/oscillatory motion. Eg: The movement/motion of a pendulum that is to and fro.

Periodic or Oscillatory Motion

• Periodic or oscillatory motion is that the motion during which a body repeats its motion after fixed intervals of your time .

• Eg: The movement/motion of a pendulum that is to and fro, Motion of a car in a circular path, Motion of planets around the sun.

Oscillations of a Simple Pendulum

• When the bob of an easy pendulum moves from its mean position B to A and back to B again, then from B to C and back to B again, the pendulum is said to complete 1 oscillation.

• In the case of the simple pendulum, the time period is the total time taken by the pendulum to complete one oscillation.

### Time and Speed

Speed (Average Speed)

• Speed is the total distance travelled by the object in a given interval of time.

• Speed = Distance travelled/time taken

• Unit of speed is generally measured in metre per second(m/s), kilometre per hour(km/h).

Uniform and Non-Uniform Motion

1. Uniform Motion: When an object moving along a line moves with a continuing speed, then the thing is claimed to be in uniform motion. Eg: A car moving in a straight line with a constant speed.

2. Non-uniform Motion: When an object moving along a line changes its speed with reference to time, then the thing is claimed to be in uniform motion. Eg: The motion of a train.

### Measurement of Time

Unit of your time is usually measured in seconds, minutes, hours. The time period is the total time taken by an object to complete one oscillation.

Units of Time

Unit of your time is usually measured in seconds, minutes, hours.

Units of Speed

• Speed = Distance travelled in the total time interval.

• Unit of speed is generally measured in meters per second (m/s) and km/h( kilometre per hour).

Speedometer and Odometer

• Speedometer records the speed of the vehicle directly in kilometers per hour (km/h).

• An odometer measures the space moved by the vehicle directly in kilometres(km).

### Visualizing Motion

Distance-Time Graph

• Distance-time graph is the graph plotted between the distance( in y-axis) and time ( in x-axis).

• The slope of a distance-time graph gives the speed of an object.

Q1. Define Distance

Ans - Distance

• Distance is the total path covered by the object in the given interval of time.

• Displacement is the shortest path covered by the moving object within the given interval of your time .

• Distance=Speed×Time.

• Unit of distance is usually measured in units of length like metres, kilometres etc.

Q2. What is Uniform and Non-Uniform motion?

Ans -

1. Uniform Motion: When an object moving along a line moves with a continuing speed, then the thing is claimed to be in uniform motion. Eg: A car moving in a straight line with a constant speed.

2. Non-uniform Motion: When an object moving along a line changes its speed with reference to time, then the thing is claimed to be in uniform motion. Eg: The motion of a train.

Q3. What is Oscillation of Pendulum?

Ans - Oscillation of Pendulum -

• When the bob of an easy pendulum moves from its mean position B to A and back to B again, then from B to C and back to B again, the pendulum is said to complete 1 oscillation.

• In the case of the simple pendulum, the time period is the total time taken by the pendulum to complete one oscillation.