CIE A Level Maths: Mechanics复习笔记1.1.4 Types of Force
Types of Force
What is a force?
- A force is a?vector?quantity, it has both?magnitude?and?direction
- A force is a push or a pull on an object
- A force is measured in?Newtons
- In A level mathematical models, forces act at a?single?point?called a?particle?which occupies a single point in space
What types of force are used in mechanics?
- Weight?is the effect of?mass?and?gravity,?it always acts downwards
- Tension?is a pulling force, it always acts away from an object
- Thrust?is a pushing force, it always acts towards an object
- Friction?is a resistive force, it acts to oppose the motion of an object
- Every surface will produce a?reaction force, it will always act?perpendicular?to the surface
Mass, Gravity and Weight
- Mass?is a measure of the amount of matter in an object
- Mass?is a?scalar?quantity, measured in?kilograms,?kg
- Mass?is universal, it does not change based on location
- Gravity?is the force by which a body (usually a planet or a star) pulls objects towards its centre
- g?is the?acceleration?due to?gravity, measured in m s-2
- On Earth,?g?is approximately?10?m s-2?, although its exact value varies with location
- g?is different elsewhere in the universe
- Weight?is the product of?mass?and?gravity, it is a?force?measured in?Newtons
- Weight?is a?vector?quantity
- Weight?varies with location
- Weight?always acts vertically downwards towards the ground
Worked Example
Exam Tip
- Always sketch a diagram and mark the forces on the diagram clearly, it will help you to understand the problem. Add more things to the diagram as you progress through the question. You may not even need all the forces from your diagram but it is useful to have them there.
- You should always round your answers to three significant figures.
转载自savemyexams
国际竞赛真题资源免费领取
美高学分项目重磅来袭！立即了解
