Physics 4 Force and Motion

C/WForces13-Oct-15 Aims:-4 know what forces do 5 explain where forces are balanced 6 apply rules to new situations Starter – 2 minutes In the back of your book, list 5 different kinds of forces

Copy notes – 3 minutes A force is a push or pull on an object Forces make things –change speed, –change direction, or –change shape. Forces in opposite directions can cancel each other out

Copy diagrams – 5 mins Pumpkin on a box Box pushes up on pumpkin Gravity pulls down on pumpkin The forces are balanced. The pumpkin doesn’t change speed, shape or direction Picture Force Diagram

Copy diagrams – 5 mins Pumpkin in mid-air Gravity pulls down on pumpkin The forces are not balanced. The pumpkin changes speed – it gets faster, downwards. Picture Force Diagram

Copy diagrams – 5 mins Racing car doing 100mph Engine pushes forward on car The forces are balanced. The car doesn’t change speed – it stays at 100mph. Picture Force Diagram Friction pulls back on car

Copy diagrams – 5 mins Racing car doing 100mph Engine pushes forward on car The forces are not balanced. The car changes speed – it gets faster. Picture Force Diagram Friction pulls back on car

Your turn – 20 minutes 1.Apple sitting on a table 2.Racing car doing 100mph but with the brakes on 3.Rocket taking off 4.Bungee jumper falling down 5.Bungee jumper being pulled back up

Homework Draw a racing car design. Label the features that increase the forward force so it can go faster Label the features that decrease the backward force (friction and air resistance) so it can go faster

Are You On Target Today? Aims:- 4 know what forces do 5 explain where forces are balanced 6 apply rules to new situations

C/WSpeed13-Oct-15 Aims:-4 know units and formula for speed 5 calculate speed 6 apply rules to changing speeds Starter – 2 minutes In the back of your book, what is missing here “John’s car goes at 100”

Copy notes – 5 minutes Speed is how far you go in a given time It can be measured in m/s, mph, cm/s etc. To work out speed remember:- Steve Digs Turnips Speed=Distance÷Time (m/s)(m)(s)

Calculations – 20 minutes 1.A car goes 50 miles in one hour 2.A bus goes 100 miles in 4 hours 3.A skateboard goes 2 metres in 1s 4.A better skateboard goes 2.5m in 1s 5.A skier goes 6m in 2s A van goes 8km in quarter of an hour A sausage falls feet in a week

Practical – 30 minutes Listen to instructions Easy option –Time the whole length –Repeat for different heights –Record results in a table Harder option –Time half way and full length –Record the first half speed and the second half speed

Plenary – Conclusion Easy option –How does the speed depend on the height of the ramp? Harder option –How do the first and second half speeds compare? –What makes the car speed up? –Draw a force diagram for the car part way down the ramp

Homework No homework this week

Are You On Target Today? Aims:- 4 know units & formula for speed 5 calculate speed 6 apply rules to changing speeds

C/WFriction13-Oct-15 Aims:-4 give examples of friction 5 explain its good and bad effects 6 use the particle model Starter – 2 minutes In the back of your book, write down three examples of where friction happens (and are they useful or a nuisance?)

Copy notes – 5 minutes Friction is a force between two surfaces It works to stop things moving Friction makes energy change into heat Useful – bike brakes –The brakes rub on the wheels –The bike’s kinetic energy is changed into heat in the brake blocks Nuisance – inside a machine –The moving parts rub together –Some of the electrical energy working the machine is turned into heat and wasted

Copy note/diagram – 5 mins Air resistance is a kind of friction Air particles collide with the moving object and push against it Air particles (magnified)Air particles hit shuttle nose, push against it and warm it up

Practical – 30 minutes Listen to instructions Easy option –Time the whole fall –Repeat for different sizes of paper –Record results in a table Harder option –As above, plus calculate the speed –Then repeat using double the weight

Plenary – Conclusion Easy option –How does the time depend on the size of the paper parachute? Harder option –Is there a relationship between the speed and the parachute size? –Use the particle idea to explain why doubling the weight doesn’t make much difference –Draw a force diagram for the paratrooper part way through the fall

Homework There was a good film a few years ago called Terminal Velocity Find out what “terminal velocity” means in physics EASY – explain it in a couple of sentences HARD – explain it using the idea of forces changing and being balanced

Are You On Target Today? Aims:- 4 give examples of friction 5 explain its good and bad effects 6 use the particle model

C/W Speed Graphs13-Oct-15 Aims:- 4 describe a journey shown in a graph 5 explain how the graph shows the speed 6 link the graph to the formula for speed

Starter – 5 minutes In the back of your book, describe your journey to school – include bits where you stop, go fast, and go slow

Video “Distance-time set-up”

Copy example Distance / m Time / mins Walks to school Stops in shop – whoops, forgot dinner money Walks fast back home Oh no, late – runs to school

Questions 1.How does the graph look when you are stopped? 2.How can you tell from the graph if you’re going fast or slow? 3.What does a downward sloping line mean? 4.How can you work out speed from the graph?

Plenary – Your journey Sketch-out the graph of your journey to school Sketch means: draw axes, use a ruler, make the graph the right shape but you don’t need numbers on the axes

Are You On Target Today? Aims:- 4 describe a journey shown in a graph 5 explain how the graph shows the speed 6 link the graph to the formula for speed