Motion in one direction

Motion

It is the change of an object position as time passe According to ( relative to) the position of another fixed object

G.R: . The motion of a train is considered as an example of motion in one direction

Bec. it moves forward and backward in straight path or curved path or combination of both

Speed

It is the distance moved through unit time

G.R: .the object speed increases by decreasing the time taken to cover a certain distance

Bec. V=D/T, so the object speed is inversely proportional to the time taken when the distance is constant

G.R: .the object speed increases by increasing the covered distance at a certain time

Bec. V=D/T, so the object speed is directly proportional to the covered distance when the time is constant

What's meant by....?

. A car moves at a speed of 120 km/h

This means that the car covers a distance of 120 km in 1 hour

What's meant by.....?

. A train covers a distance of 150km in 2 hours

This means that the train moves at a speed equals 75km/h

Where V=D/T =150/2=75 Km/h

What's meant by....?

. The speed of a car equals zero

This means that the car is at rest

G.R: . Cars and planes are provided by speedometer

To help us identify the speed of cars and planes directly

At fixed time:

G.R: the red car is faster than the blue car

Bec. the red car covers large distance in the same time

At fixed distance:

G.R: the red car is faster than the blue car

Bec. the red car takes less time to cover the same distance

Regular Speed

It is the speed which an object moves when it covers equal distances at equal periods of time

Irregular Speed

It is the speed at which the object moves when it covers unequal distances at equal periods of time

Or

It is the speed at which the object moves when it covers equal distances at unequal periods of time

What's meant by…?

An object moves at a regular speed of 50 km/h

This means that the object covers a distance of 50 km in each hour

G.R:

Most of moving car cannot move inside crowded towns all the time at uniform speep

Bec. the speed of the car changes according to the conditions of the road

(due to traffic conditions)

G.R:

The metro moves at irregular speed

Bec. the metro covers unequal distances at equal periods of time or

it covers equal distances at unequal periods of time

Average Speed

It is the total distance covered by the moving object divided by the total time taken to cover this distance

Or

It represents the regular speed at which an object moves to cover the same distance at the same periods of time

Or

It's a regular speed by which the car covers equal distances and equal periods of time

When does the following happen…?

The value of average speed of a moving object equal to it's speed at any moment

When the body moves at a regular speed

The value of average speed of a moving body differs from the value of its peed at any moment

When the body moves at an irregular speed

Relative Speed

It's a speed of a moving object relative to a static or a moving observer

Or

It's a speed of a moving object relative to the position of an observer

G.R:

The moving cars seems to be stable (at rest) to an observer moves at the same speed at the same direction

The relative speed equals the difference between their speeds equals 0

BEC.

The difference between their speeds equals 0

What's meant by…?

The relative speed of a car is 90 km/h

This means that the speed of the car relative to an observer =90 km/h

The relative speed of a moving car =it's real speed

This means that the observer is a rest

The relative speed of a moving car =70 km/h to an observer moves in the opposite direction at a speed 20 km/h

That means that the speed of the car = 50 km/h

When does the following happen….?

The relative speed of a moving object relative to an observer =to 2 of its real speed

When the observer moves in the opposite direction at the same speed of the moving object

Thr relative speed of a moving object relative to an observer equals 0

When the observer moves in the same direction at the same speed of the moving object