Three years ago I explained how to use photographs to estimate the speed of a passing car. You can read that article at https://physbang.com/2020/08/02/keep-the-cogs-turning/. Now it is time to use a similar technique to answer a more challenging question: what is the take-off velocity of a passenger jet? Of course, the answer could be found … Continue reading Aircraft take-off velocity
Motion Along a Line
Having looked at the first Physics paper for this year's AQA Trilogy examination, it seems to me that a significant proportion of questions have been framed around situations and applications rather than just recalling and connecting facts. With that in mind, let's take a real-world look at motion along a line... First an important definition. … Continue reading Motion Along a Line
Determination of ‘little-g’
One of my favourite experiments in GCSE physics is a practical that seems to have fallen from favour in recent years – but it’s still worth exploring. The experiment involves using a ticker-timer to make dots at regular time intervals (0.02 s apart) on a strip of tape that is attached to a moving object. … Continue reading Determination of ‘little-g’
Forces and Motion
Let’s get the common misconception out of the way first: moving objects do not remain in motion because there is a force that keeps them going. In fact, it’s the opposite. Moving objects always remain in the same state of motion unless an external force stops them. By “the same state of motion” we mean … Continue reading Forces and Motion
Measuring Speed
This is the third part of a mini-series looking at motion and here we’ll be considering different ways to measure speed as well as some common sources of error. In theory, speed is easy; we just need a distance (measured using a ruler, for example) and a time (probably measured using a stopwatch but ideally … Continue reading Measuring Speed
Speed and Acceleration
When a stationary object starts moving in a straight line, its motion can be divided into two stages. The first stage is when the speed of the object is increasing; the second stage is when the object has reached a steady speed. We can rephrase these two stages using the word acceleration; the first stage … Continue reading Speed and Acceleration
Speed and Velocity
In many situations, the word “speed” is used when in fact “velocity” would sometimes be more appropriate. Speed is the rate of change of distance: the word “rate” indicates time, so speed is simply a measure of how much the distance changes in each second of movement. If you took 80 seconds to run 400 … Continue reading Speed and Velocity
Heisenberg and Sheldon; speed and uncertainty
In my very last Y11 lesson of last term I did a 15-minute dash through some of the weirder bits of physics, including Heisenberg's uncertainty principle. This says that, for example, you cannot know the exact values of an object's position and speed (actually its momentum). More excitingly, you cannot know the exact energy of … Continue reading Heisenberg and Sheldon; speed and uncertainty
Squirrel speed
How fast can a squirrel run? I'm talking here about a red squirrel (the type we have in Jersey) and I'm assuming that the creature has been startled and is dashing for cover. Think for a moment: what sort of experiment could you arrange to answer this question? At its simplest, this is a time-and-distance … Continue reading Squirrel speed
Flight facts
How long do you think it takes to get to cruising altitude on a long-haul flight? Aircraft travel has become so smooth that you could be forgiven for thinking that within 20 minutes, at the most, you're in level flight. And you would probably also think that the aircraft's speed is fairly constant from about … Continue reading Flight facts
Mr Tarrant's physbang 'blog 