Introduction

You might think that NASA use the more complicated and accurate laws of Relativity discovered by Einstein in 1905. But in fact all space missions are navigated by Newton’s laws of motion from 1687. Newton’s laws of motion (resultant force produces an acceleration proportional to mass, and all forces exist in equal and opposite pairs) produced an astounding revolution in science. For the first time, we could predict exactly how all things move, from tiny cells to gigantic galaxies. This unlocked a huge transformation in our understanding, giving birth to most of the technologies that are so vital in our lives today. Most modern engineering, and much more besides, still builds directly on this foundation. Take time to gain a really deep appreciation of these extremely simple but profound principles; they are the key to a clear understanding for much of the rest of this course.

Reading

Edexcel International AS/A Level Physics Student Book 1 pages 20 to 22

Tasks

Complete the following:

Read pages 20 to 22 of the textbook.

WATCH – Mechanics – Introduction to Classical Mechanics (MASSOLIT)

WATCH and COMPLETE – Newton’s Three Laws (Khan Academy) Work through all of the Khan Academy tutorials. Watch all the videos and answer all the ‘Practice Questions’ on the right.

WATCH – 3 Incorrect Laws of Motion (YouTube)

WATCH – Newton’s Three Laws of Motion (YouTube)

WATCH – Mechanics – Newton’s First Law of Motion (MASSOLIT)

COMPLETE – Gameboard: Newton’s 2nd Law (Isaac Physics)

WATCH – Force is Directly Proportional to Acceleration (F = ma) (YouTube)

WATCH – Mechanics – Newton’s Second Law of Motion (MASSOLIT)

WATCH – F = ma and W = mg (YouTube)

WATCH – Newton’s 3rd Law (YouTube)

WATCH – Mechanics – Newton’s Third Law of Motion (MASSOLIT)

COMPLETE – Gameboard: Newton’s 3^rd Law (Isaac Physics)

Read the Practical Skills box and learning tip on page 21.
Complete the questions on page 22. You will find the answers in General Resources under the heading Textbook Answers.

Top Tips

Make sure that you understand the following key points:

Memorise $LaTeX: \Sigma F = ma$ . (Resultant force = mass x acceleration).
All forces exist in pairs: same type and size, opposite directions, different objects.
When defining Newton’s first law of motion, take care to refer to constant velocity rather than to constant speed.
Identifying Newton’s third law of force pairs, remember they must always act on different objects, and must always have the same cause.

Key Terms

Add the following key terms with definitions to your word list:

Newton’s first law of motion
Newton’s second law of motion
Newton’s third law of motion
Resultant force
3^rd- law pair