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axis. The moon revolves around the Sun. The sun moves in the galaxy. The

galaxies move with respect to one another.

2

If an object changes its position (the location of an object), we say that

motion has occurred. When an objet is undergoing a continuous change in

position, we say the object is moving or is in its motion. We describe motion in

terms of distance and time. Two basic kinds of motion are straight line motion

and circular motion.

3

The terms speed and velocity are often used interchangeably. In physical

science, however, these terms have distinct meanings. The basic difference is

that one is a scalar quantity and the other one a vector quantity.

4

A scalar quantity is one that has magnitude or size only. For example, you

may be travelling in a car at 90 km/h. This figure is your speed. A vector

quantity, on the other hand, is one that has magnitude and direction. For

example, suppose you are travelling 90 km/h north. This quantity describes your

velocity.

5

The average speed of an object is the total distance travelled divided

by the time spent in travelling the total distance. In formula form we have:

distance travelled d

Speed = V =

time to travel distance t

6

When you drive down a straight highway and suddenly increase your

speed, you feel as though you are being forced back against the seat. When

driving fast on a circular cloverleaf, you feel forced to the outside of the circle.

These experiences result from changes in velocity (speed in a certain direction)

or, in other words, from acceleration.

7

There are three ways that you can change the velocity of an object. You

can (1) increase or (2) decrease its magnitude when travelling in a straight line,

or (3) you can change the direction of the velocity vector. When any of these

changes occur, we say that the object is accelerating. The faster the change in

4 axis. The moon revolves around the Sun. The sun moves in the galaxy. The galaxies move with respect to one another. 2 If an object changes its position (the location of an object), we say that motion has occurred. When an objet is undergoing a continuous change in position, we say the object is moving or is in its motion. We describe motion in terms of distance and time. Two basic kinds of motion are straight line motion and circular motion. 3 The terms speed and velocity are often used interchangeably. In physical science, however, these terms have distinct meanings. The basic difference is that one is a scalar quantity and the other one a vector quantity. 4 A scalar quantity is one that has magnitude or size only. For example, you may be travelling in a car at 90 km/h. This figure is your speed. A vector quantity, on the other hand, is one that has magnitude and direction. For example, suppose you are travelling 90 km/h north. This quantity describes your velocity. 5 The average speed of an object is the total distance travelled divided by the time spent in travelling the total distance. In formula form we have: distance travelled d Speed = V= time to travel distance t 6 When you drive down a straight highway and suddenly increase your speed, you feel as though you are being forced back against the seat. When driving fast on a circular cloverleaf, you feel forced to the outside of the circle. These experiences result from changes in velocity (speed in a certain direction) or, in other words, from acceleration. 7 There are three ways that you can change the velocity of an object. You can (1) increase or (2) decrease its magnitude when travelling in a straight line, or (3) you can change the direction of the velocity vector. When any of these changes occur, we say that the object is accelerating. The faster the change in

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