Graphics can possibly represent the relation between speed and time in a moving car.

If the car starts moving from rest (speed = zero) and after one minute its speed becomes 30 km/hour.

After another minute, its speed increases to 60 Km/hour.

Then, the motorist had to use the

brakes

to slow down the car’s speed to 20 km/hour in the third minute and he stops completely after another minute. It is possible to represent the movement graphically

1-Regular speed

Activity

To discover: representing uniform speed graphically

Tools:

A toy car operated by a battery – a smooth wooden board of about 3 meters – a metric ruler or a metric strip – a stop watch

The relation between distance (d) and time (t),

We can draw a graph of the measured quantities.

We use distance (d) on the vertical axis (Y axis) and time on the horizontal axis (X axis)

Then, we place the reading in the table in the shape of dots.

When we match these dots together, we find that they are located on a straight line passing the intersection point of the two axes. (the origin point)

Observation

All points lie on a straight line passing the intersection point of two axes (origin point)

Conclusion

The distance (d) is directly proportional to the time (t)

The ratio ( d/t ) is constant value which represents the regular speed

The distance-time graph for an object moves with uniform speed is straight line passing through the origin point

Draw the relation between speed (V) and time (t),

we get a graphic relation as shown in the figure.

Use the previous table to draw the

graphic relationship between speed (V) and time (t)

Observation

All points lie on a straight line parallel To the time (X) axis

Conclusion

The speed remains constant as time passes

The (speed-time)graph for an object moves with regular (uniform) speed is a is straight line parallel to the time axis

**Graphic representation of moving**

in a straight line

in a straight line

Thanks

Wait For Part 2

**Mr.Ahmed ElBasha**

Procedures:

1-Place the wooden board at a horizontal position.

Put two marks at a known distance on the wooden board Measure the distance between them (d).

2- Operate the car, and during that, another student calculates the time (t) necessary to cover this distance.

3-A third student repeats the experiment changing the two marks.

4-Exchange tools with your colleagues and repeat the experiment.

5-Write the results in a table.

6-In each time, calculate the speed of the car from the relation:

V= d/t.

Some facts are clarified about regular movement in a straight line.

1- The (distance-time) graph for regular motion at constant speed is represented by a straight line passing through the origin point

2- The (speed –time) graph for regular motion at constant speed is represented by a straight line parallel to the time axis

Mr.Ahmed ElBasha

**Part 1**