What is motion…

A cloud moving in the sky…?

A sprinter moving down a track…?

Water level rising in a bath tub…?

A minute hand moving on a clock…?

1.) ___________________________

2.) ___________________________

3.) ___________________________

How can we describe different types of motion?

1.) Measure distance and time

2.) Create a map showing various positions

What is an object in motion? An object is in motion when its distance from another object is changing…

Units of measureTo describe motion, you need to use units of measurement.

Scientists all over the world use the same system of units so that they can communicate information clearly.

This system is called the International System of Units.

- SI is based on the number 10. - The SI basic unit of length is the meter.

Objects in motionWhile moving objects are very common in our daily lives,measuring the motion of an object is a very sophisticated notion.YOU will be introduced to FOUR useful ways of measuring anddescribing motion…

SpeedSpeed measurement consists of a unit of distance by a unit of time.

So…

If you measure distance in meters and time in seconds, you express the speed in meters per second.

To calculate: speed = distance/time

If you know the distance an object travels in a certain amount of time, you know the speed of the object.

VelocitySpeed in a given direction is called velocity.

So…

When you know both the speed and direction of an object’s motion, you know the velocity of the object.

Knowledge of velocity is important to:

-Air traffic controllers-Weather forecasters-Stunt pilots

AccelerationAcceleration is the rate at which velocity changes (remember, velocity has 2 components – speed and direction).

In science, acceleration refers to increasing speed, decreasing speed or changing direction.

So…acceleration involves a change in either speed or direction.

Calculating acceleration…Acceleration describes the rate at which velocity changes…

So to determine the acceleration of an object, you must calculate the change in velocity during each unit of time.

Acceleration = Final velocity – Initial velocity Time

Graphing motionYou can show the motion of an object on a line graph in which you plot distance against time. A point on the graph represents the location of an object at a particular time.

X-axis = timeY-axis = distance

distance

time

Graphing motionYou can use a graph to analyze the motion of an object that is accelerating (Speed vs Time).

If acceleration is constant, for every increase in unit of time that the speed increases in the same amount, the graph will be a straight line.

If the object accelerated by a different amount for each unit of time, the graph would not be a straight line.

1. The motion of an object is determined by its change of position relative to a reference point.

2. Speed is the distance an object travels in one unit of time. Speed can be determined by dividing the distance it travels by the time taken (this will give you the object’s average speed).

3. When you state both the speed of an object and the direction in which it is moving, you are describing the object’s velocity.

4. Acceleration is the rate at which velocity changes. It involves increasing speed, decreasing speed or changing direction.

5. Acceleration can be calculated by dividing the change in velocity by the amount of time it took that change to occur.

Key ideas about Motion and You!

Now for some fun…!