G481.1 Motion

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Lesson 1- Physical Quantities+Units

Motion: What Physical Quantites are and what units go with them.
Using Numerical Prefixes.

Lesson 2 - Vectors and Scalars

Motion: What Vectors and Scalars are and examples of them.

Lesson 3 - Vector Addition

Motion: Adding Vectors in 2 dimensions and using Pythagoras' Theorem to find the size of the resultant.

Lesson 4 - Components of a vector

Motion: Finding the components of a resultant vector by using trigonometry.

Lesson 5 - Gatso Speed Cameras

Motion: HOW SCIENCE WORKS.
How GATSO Speed cameras work.

Lesson 6-Displacement Time Graphs

Motion: Defining displacement and using displacement-time graphs to describe motion.

Lesson 7 - Velocity Time Graphs

Motion: Defining velocity and using velocity-time graphs to describe motion.

Lesson 8 - Motion Graphs Review

Motion: Using displacement-time and velocity-time graphs to find velocity, acceleration and displacement.

Lesson 9 - Uniform Acceleration

Motion: Deriving the equations of motion (suvat equations) and using them.

Lesson 10 - Motion under Gravity

Motion: Practical use of the equations of motion. Describing an experiment to find acceleration due to gravity.

Lesson 11 - Projectiles intro

Motion: What a projectile is and what path one follows.

Lesson 12 - Projectiles challenge

Motion: Applying the equations of motion to projectile motion.

Lesson 13 - Projectiles Practise

Motion: Applying the equations of motion to projectile motion.

Lesson 14 - G481.1 Module Review

Motion: Test yourself on Motion.

Lesson 15 - Newton's 2nd Law

Forces in action: Using Newton's 2nd Law and defining the Newton.

Lesson 16 - Newton 2 practise

Forces in action: Questions using Newton's 2nd Law.

Lesson 17 - Non-Linear Motion

Forces in action: Describing the motion of projectiles travelling in a fluid.

Lesson 18 - Equilibrium Definitions

Forces in action: Describing equilibrium and using the triangle of forces.

Lesson 19 - Moments and Couples

Forces in action: Describing moments and couples.

Lesson 20 - Equilibrium Examples

Forces in action: Using the principle of moments to do questions involving practical situations.

Lesson 21 - Density and Pressure

Forces in action: Describing density and pressure and their units.

Lesson 22 - Forces on Vehicles

Forces in action: Describing the factors that affect stopping distance.

Lesson 23-Physics of vehicles intro

Forces in action: Describing how air bags, seat belts and crumple zones work and looking at how GPS works.

Lesson 24 - Physics of vehicles

Forces in action: Describing how forces are reduced by using air bags, seat belts and crumple zones.

Lesson 25 - G481.2 Review

Forces in action: Test yourself on Forces in action.

Lesson 26 - Work and energy

Work and Energy: Defining work done and the Joule and using the equation.

Lesson 27 - Energy Changes

Work and Energy: Defining the conservation of energy and describing some examples.

Lesson 28 - GPE to KE

Work and Energy: Describing the interchange between gravitational potential energy and kinetic energy using equations.

Lesson 29 - Power

Work and Energy: Describing power and the Watt.

Lesson 30 - Efficiency

Work and Energy: Describing energy efficiency.

Lesson 31 - Spring Constant

Work and Energy: Looking at elastic materials and using Hooke's Law.

Lesson 32 - Strain Energy

Work and Energy: Describing the energy stored in elastic materials.

Lesson 33 - Young Modulus

Work and Energy: Describing Stress and Strain of materials, the definition of the Young Modulus and describing experiments to find it.

Lesson 34 - Material Properties

Work and Energy: Defining the terms elastic deformation and plastic deformation of a material. Looking at stress strain graphs for ductile, brittle and polymeric materials.

Lesson 35 - G481 Review

Work and Energy: Test yourself on Work and Energy.

Lesson 4 - Components of a vector

Keywords

Scalar, Displacement, Vector, Force, Velocity, Resultant, Perpendicular

Objectives

You should:

(d) resolve a vector such as displacement, velocity and force into two perpendicular components.

Starter

Watch the video at the top of the page about vector addition.

Introduction

Read through these notes on Vectors components.

Resolving Vectors

Resolving a vector is the process of taking the resultant vector and working out its magnitude in two perpendicular directions.
The easiest way to understand this is with an example:

A ball is kicked at 10 ms-1 at an angle of 30° to the horizontal. What are the horizontal and vertical components of its velocity?
vectors 

The vector triangle would look like this:
vectorsvectors 

From our knowledge of Trigonometry we can say that:
sin30°= Vv / 10 ms-1
And
cos30°= Vh / 10 ms-1
(Don’t forget soh, cah (and toa))
So we could rearrange these to get:
Vv = 10 sin30°
And
Vh = 10 cos30°
So in this case Vv = 5 ms-1 and Vh = 8.7ms-1

Remember that the hypotenuse is 10 and this is the longest side, so if either of your components is bigger than 10 then you know you’ve done something wrong.

Perpendicular Vectors

Imagine trying to move a toy car by pushing it.

vectors

If you wanted to move it to the right you would push it from the left:

vectorsvectors

If you wanted to move it up you would pull it from the top:
vectors 

vectors

You can see that no matter how hard you pushed it from the left, the car would never go upwards. And the same is true that no matter how hard you pulled the car up, it would never go left or right.

These vectors (perpendicular ones) are independent of each other and can be treated individually when doing calculations. This becomes very important when looking at projectile motion in lesson 23.

For a printable version of these notes click here.

Development

Work through the powerpoint. You'll need some graph paper, a ruler, pencil and a calculator.

Plenary - Check your understanding

Read through this example and then try the question below:

You set off to run across as empty supermarket parking strip, 100 m wide. You set off at 55° to the verge, heading towards the entrance to the supermarket. Your speed is 8 m s-1. How long will it take you to reach the far entrance?

diagram

Find the component of your velocity directly across the parking strip.  The angle between your velocity and the direction of interest is 35° (why?). So:
component of velocity across the parking strip = v × cos q = 8 m s–1 × cos 35° = 6.55 m s-1.
Find the time it will take to travel 100 m at this speed:


equation


You will reach the far side of the parking strip in a little more than 15 s.
Notice that calculating the time only involves the component of velocity directly across the parking strip. You can go on to calculate how far along the opposite side of the parking strip you will arrive.

Find the component of your velocity along the parking strip. The angle between your velocity and the direction of interest is 55°. So:
component of velocity across the parking strip = v × cos q = 8 m s-1× cos 55° = 4.59 m s-1.

Find the distance travelled at this speed in 15.3 s:

distance = speed × time = 4.59 m s-1 × 15.3 s = 70.2m

So you will finish up about 70 m further along the parking strip. Notice that this calculation only involves the component of velocity along the parking strip.

Question

A train is gradually travelling up a long gradient. The speed of the train is 20 m s-1 and the slope makes an angle of 2° with the horizontal. The summit is 200 m above the starting level. How long will it take to reach the summit?

train up a hill

click here for the answer.

Outcomes

You should check through these outcomes. If there is anything you can't do, check through the page again before you do your homework.

(d) resolve a vector such as displacement, velocity and force into two perpendicular components.

Homework

Now print out the Exam Questions and try them. These are the same standard as the questions you will get in your exam. As you get close to taking the exam, you should try to answer these so that it takes you 1 minute to get through a 1 mark question.

Below is a very rough guide to what grade you will achieve for the percentage gained.

%

Grade

80

A

70

B

60

C

50

D

40

E

Check with your teacher to find out what your target grade is based on how you did at key stage 4 but remeber some topics are easier than others and so it is the overall average that really counts.