# تلخيص الدرس الثالث فيزياء صف تاسع متقدم

الصف الصف التاسع المتقدم فيزياء الصف التاسع المتقدم فيزياء تاسع متقدم فصل اول 1.99 MB 563 2020-07-10, 19:16 مساء

Phy40-lesson 3

Position -time graph

1. Plot data as a position-time graph for single and multiple objects and analyze the position-time graphs.

2. Solve problems involving single and multi-particles as well as problems involving instantaneous position

When analyzing complex motion, it often is useful to represent the motion in a variety of ways. A motion diagram contains information about an object's position at various times. Tables and graphs can also show this same information.

Even though there is no data point exactly when the runner was 12.0 m beyond her starting point or where she was at t = 4.5 s, you can use the graph to estimate the time or her position.

A straight Line means Constant speed

Position (m) ® time (s)

0 ® 0

2 ® 4

4 ® 8

5 ® 10

3 ® 6

A constant speed is represented by a line in the position-time graph.

1. If the line is horizontal, the object is at rest.

2. If the line is going upwards, the object is moving at constant speed in the positive direction

3. If the line is going downwards, the object is moving at a constant speed in the negative direction

Describe the motions of person 1, person 2, and person 3 above.

person 1 is at rest

person 2 constant velocity negative direction

person 3 constant velocity positive direction

The steeper the line the faster is the object

Who is the fastest? Why

Albert, because the line is the steepest

Who is the Slowest? Why

Michael, because the line is least steep.

Instantaneous position

The position at a particular instant. Instantaneous position is usually simply called position.

Example: What is the instanteneous position of the object at 1s, 2.5s?

Multiple Objects on a Position-Time Graph

The graph to the right describes the motion of two runners moving along a straight path. The lines representing their motion are labeled A and B.

Who is faster Runner A or B? Explain why.

B is faster because the live is steeper

When and where does runner B pass runner A?

at t=45s and x=190m

How far apart were runners A and B at t = 20.0 s?

XB=60m XA=80m A was 20m in front of B