Day+4,+Forces+and+motion.


 * Forces and motion.**


 * <>day 5 >> ||

You will need to be able to distinguish between speed and acceleration from data, motion/time graphs and ticker tape traces. You should know and be able to use the quantitative relationship between speed, distance and time to solve problems.

Ticker timers are useful for students to look at acceleration qualitatively. The dots on the tape tell a story. Although fiddly, working out speed and acceleration from ticker tape is good practice at using the calculations. Crumple zone and crash safety activities benefit from practice runs with ticker tape. Also worth using to analyse movement are proximity sensors, light gates, cameras/video/phones as well as 'live' methods - this can lead on to interesting work on errors and accuracy. A good, engaging activity is "How accurate is my car's speedometer?" or "Can I use my videophone as a speed camera?" With a topic like speed there are many opportunities for stimulating practical work. Think about offering a choice of focus - gender differences; some students might be interested in crashing cars but for others a focus on designing a crash-safe child seat or a sensor for detecting falls for the elderly in sheltered accommodation might be more appealing. With appropriate risk assessments you can have quite a lot of fun - in the past I've had teams compete to get the highest acceleration while pushing my car, measuring the speed of a jumping skateboarder and investigating the muzzle velocity of a mortar made from a Pringles tube. Other examples include using ICT to investigate the cornering speed of Scalextric cars and running combined events with the PE faculty on measuring sports performance. Motion/time graphs are a good opportunity to engage the creative side of learners. Proximity sensors can also be a good way of making this otherwise dry topic more engaging.

Students should appreciate the differences between vector quantities like displacement and velocity and scalar quantities like distance and speed.

Units can be a good lead into the quantitative work - that 60mph is a mile a minute is a good way in for the less mathematically confident. Converting between units is a good exercise for the more confident. Introducing units for acceleration can be intimidating - go slowly and build up the concept before leaping into the maths.

Quantitative problems can be a sticking point for some students. Encourage students to sketch the situations and to sketch graphs and to tie the various ways of looking at problems together conceptually. Remembering things like 'distance travelled is area under speed/time graph' can be the key to finding a solution. Devising questions is also a good approach for gifted students (and physics teachers) for consolidating understanding. Be imaginative with your questions!

There are lots of simulations that can aid teaching of dynamics - PhET from the Universtiy of Colorado offer a lot of different Java-based sims.

This session also contains a brief introduction to Galilean relativity (or Galilean invariance) - relevant when we need to apply thinking about motion to understand Einstein's theories. There's a good, succinct introduction here on Suite 101 and some nice animations here on EinsteinLight.

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