### ВУЗ:

Составители:

Рубрика:

15

balanced, that is, equal and opposite, motion doesn’t occur. It occurs when the

applied forces are unbalanced, that is, when they are not equal and opposite. An

external force is one that is applied on or to the object or system. There are also

internal forces but they don’t affect velocity.

5

Galileo also introduced another concept. It appeared that objects were

resistant to changes in motion. Similarly, if an object was at rest, it seemed to

“want” to remain so. Galileo called this property inertia and we say that inertia

is the property of matter that resists changes in motion.

6

Newton went on one step further and related the concept of inertia to

something that could be measured – mass. That is, mass is the measure of

inertia. The greater the mass of an object, the greater its inertia is and vice

versa.

7

As an example of the relationship of mass and inertia, suppose you

horizontally push two different people on swings initially at rest, one a very

large man and the other a small child. You’d quickly find that it was more

difficult to get the adult moving. That is, there would be noticeable difference in

the resistance to motion between the man and the child. Also, once you got them

swinging and then tried to stop the motions, you’d notice a difference in the

resistance to a change in motion again. Being more massive the man has greater

inertia.

8

In our study of motion, acceleration was defined as the time rate of the

change of velocity. What causes acceleration? Newton’s first law answers the

question. If an external unbalanced force (net force) is required to produce a

change in velocity, then we see that an unbalanced force causes an acceleration.

Newton also related acceleration to inertia or mass. Because inertia is the

resistance to a change in motion, a reasonable assumption is that the greater

inertia or mass of an object, the smaller the change in motion or velocity is when

a force is applied. Hence we have this summary:

1. The acceleration produced by an unbalanced force acting on an object

(or mass) is directly proportional to the magnitude of the force (a ∝ F)

and in the direction of the force.

2. The acceleration of an object being acted on by an unbalanced force is

inversely proportional to the mass of the object (a ∝

1/m).

15 balanced, that is, equal and opposite, motion doesn’t occur. It occurs when the applied forces are unbalanced, that is, when they are not equal and opposite. An external force is one that is applied on or to the object or system. There are also internal forces but they don’t affect velocity. 5 Galileo also introduced another concept. It appeared that objects were resistant to changes in motion. Similarly, if an object was at rest, it seemed to “want” to remain so. Galileo called this property inertia and we say that inertia is the property of matter that resists changes in motion. 6 Newton went on one step further and related the concept of inertia to something that could be measured – mass. That is, mass is the measure of inertia. The greater the mass of an object, the greater its inertia is and vice versa. 7 As an example of the relationship of mass and inertia, suppose you horizontally push two different people on swings initially at rest, one a very large man and the other a small child. You’d quickly find that it was more difficult to get the adult moving. That is, there would be noticeable difference in the resistance to motion between the man and the child. Also, once you got them swinging and then tried to stop the motions, you’d notice a difference in the resistance to a change in motion again. Being more massive the man has greater inertia. 8 In our study of motion, acceleration was defined as the time rate of the change of velocity. What causes acceleration? Newton’s first law answers the question. If an external unbalanced force (net force) is required to produce a change in velocity, then we see that an unbalanced force causes an acceleration. Newton also related acceleration to inertia or mass. Because inertia is the resistance to a change in motion, a reasonable assumption is that the greater inertia or mass of an object, the smaller the change in motion or velocity is when a force is applied. Hence we have this summary: 1. The acceleration produced by an unbalanced force acting on an object (or mass) is directly proportional to the magnitude of the force (a ∝ F) and in the direction of the force. 2. The acceleration of an object being acted on by an unbalanced force is inversely proportional to the mass of the object (a ∝ 1/m).

## Страницы

- « первая
- ‹ предыдущая
- …
- 13
- 14
- 15
- 16
- 17
- …
- следующая ›
- последняя »