Speed

• Physics
• Secondary Education
• Age 13

Forces and Motion

Lesson 06. 

TURNING FORCES

How are you today?

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Highlights of the Day

• describe the effects of balanced and unbalanced forces on motion
• calculate speed (speed = distance / time)

• Value :  Responsibility

Think about...

What is the speed limits
for cars in Cambodia?

There are many different units of speed.

TRUE

FALSE

Forces and Motion

Lesson 04. 

SPEED

Units of Speed

knots  ( example: 5 knots )          -  for ships

Mach   ( example: 5000 Mach)   -  for aeroplanes

kilometers per hour  (example: 5 km/hr)  - roads

miles per hour  (example: 500 miles/hr)  - roads

The problem: 

                confusion as to what will be used

Which of the following do scientists use as "standard unit for speed"?

1. meters per hour
2. meters per second
3. miles per second
4. miles per hour

In 50 meters "per" second, what does "per" mean?

1. in all
2. in each
3. multiply
4. add

What does "meters per second" mean?

1. the number of meters travelled in one second
2. the number of seconds in one meter
3. the number of meters in a straight line
4. one meter per one second

What do you mean by "5 meters per second"?

1. the object travels a distance of 15 meters in each second
2. the object travels a distance of 15 seconds in each distance

How do you write "meters per second"?

1. ms
2. m/s
3. msp
4. s/m

QUESTION TIME!

Calculating Speed

Equation for Speed

What does it mean by "average speed"?

1. The speed of an object during a journey is NOT always constant.
2. The speed of an object during a journey is always constant.

Steps in Calculating Speed

• Read and analyse the problem.
• Underline all the numbers with its units.
• Identify the formula.
• Identify what you the problem is looking for.
• Substitute all the numbers and units in the formula.
• Circle or box your final answer.

Practice

Question 1:

Marcus rides his bicycle at a speed of 5 m/s for 60s. How far does he go in this time?

Question 2:

Sofia is in a car traveling at a speed of 30 m/s. How long will the car take to travel 2100 m?

Question 3:

An aeroplane travels 3500 km in a time of 5 hours. What is the speed of the aeroplane in km/h?

Question 4:

A car travels a distance of 210 m in a time of 6s. Calculate the speed of the car in m/s.

Summary

Equation for Speed

Self-survey: Rate your level of understanding and participation in this lesson.

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