Question

Give me some important points for the chapter motion that can come in exam of class 7 .

Give like one word answer...

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Answer 1

Answer:

Explanation:1. What is Motion?

If an object keeps on changing its position with time, it is said to be moving or in motion. Motion can be of different types:

*Linear or straight in which the object travels in a straight line.

*Circular in which the object travels along a circular path.

*Curvilinear in which the object moves along a curve

2.Slow and Fast Motion

If one object covers a particular distance in less time and another object covers the same distance in more time then the first object is said to be moving slowly while the second object is said to be moving faster.

The Speed of an object

The distance travelled by an object in unit time is called its Speed.

3.Measuring Time

There are many events in nature that repeat after a time interval:

Morning – The rising of the sun

Day and Night – The time between the sunrise and sunset

Month – The time between two new moons

Year – The time the earth takes to complete its one revolution around the sun

Time measuring devices or clocks - Clocks use the concept of periodic motion to measure time. It means that it uses motion that repeats itself in equal amounts of time. There are different types of time measuring devices.

1.Sundial – It uses the position of the sun to depict time

2.Sand Clock (hourglass) – It uses sand to measure time

3.Water Clock – It uses water to measure time

4.Pendulum Clock – It uses a pendulum to measure time

5.Quartz Clocks – They have an electric circuit that works with the help of cells. They provide accurate time.

Answer 2

Answer:

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An Introduction to Motion

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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 in the given interval of time.
• Distance=Speed×Time.
• Unit of distance is generally measured in units of length like metres, kilometres etc.

Introduction to motion

An object is said to be in motion if it changes its position with respect to time.

• Eg: A car moving on a road.

An object is said to be at rest if the object does not 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 time is in seconds (s).
• The standard unit of speed is in metre per second (m/s).

Basics of Motion and Its

Types

Types of motion

Types of motion are generally divided into 3. They are:

• 1. Rectilinear / translatory motion: When a body is moving in a straight line, without changing its direction, then the body is said to possess translatory/rectilinear motion.

Eg: A car moving on a straight road.

• 2. Circular motion: When a body moves in the shape of a circle about a fixed point and a fixed radius, then the body is said 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 time, then the body is said to in the periodic/oscillatory motion.

Eg: To and fro motion of a simple pendulum.

Periodic or oscillatory

motion

Periodic or oscillatory motion is the motion in which a body repeats its motion after fixed intervals of time.

Eg: To and fro motion of a simple pendulum, Motion of a car in a circular path, Motion of planets around the sun.

Oscillations of a simple pendulum

When the bob of a simple 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 completeness 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 straight line moves with a constant speed, then the object is said 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 straight line changes its speed with respect to time, then the object is said to be in uniform motion.

Eg: The motion of a train.

Measurement of Time

• Unit of time is generally 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 time is generally measured in seconds, minutes, hours.

Units of Speed

• Speed = Distance travelled in the total time interval.
• Unit of speed is generally measured in metre per second (m/s) and km/h( kilometre per hour).

Speedometer and Odometer

• Speedometer records the speed of the vehicle directly in kilometre per hour (km/h).
• An odometer measures the distance 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.