Despite having previously examined a phase-change diagram in detail (here) I haven't yet covered the particle model and how it links to different states of matter. So that topic, which is relevant for both chemistry and physics, is the focus of this article. First let's clarify the terminology... we will be confining ourselves to the … Continue reading Changes of State
Resultant Forces (part 3)
In the final part of this mini-series, we have to deal with situations where the two component forces are neither opposite nor at right angles; the forces are simply at some general angle to each other. Typical situations where this could apply in real life are tugs pulling a ship or an airplane flying through … Continue reading Resultant Forces (part 3)
Resultant Forces (part 2)
In the first part of this mini-series we looked at forces that act in exactly opposite directions. We noted that although these forces can be subtracted, the correct procedure is to combine the forces in more rigorous way that clearly takes account of both their magnitude and their direction. The most powerful way to do … Continue reading Resultant Forces (part 2)
Momentum
Newton's Second Law of Motion tells us that the force required to accelerate an object can be calculated by multiplying the mass of the object by the acceleration that is required (F=ma). We also know that acceleration is simply the rate of change of velocity (the change in velocity divided by the time taken for … Continue reading Momentum
Force and Acceleration
There are various techniques that can be used to investigate the relationship between force, mass and acceleration (Newton’s Second Law of Motion). In a school lab, we often use a dynamics trolley (wheeled platform) that is attached to a mass hanger via a string that runs over a desk pulley. The mass hanger provides the … Continue reading Force and Acceleration
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
Thawing a frozen balloon
The pressure, volume and temperature of a gas are all linked so it makes sense to keep one of them constant when investigating the interdependence of the other two. But we didn't do that when we watched the effect of liquid nitrogen on a partially-inflated balloon - as shown in the animation below. Before viewing … Continue reading Thawing a frozen balloon
Summer Challenge
You may have better things to do during the summer vacation but, in case you find yourself getting bored, I have an investigation that you might like to tackle. The work is open to all of my students, both those of you who are still studying the GCSE course and those who have just finished … Continue reading Summer Challenge
Under(water) Pressure
Pressure explains why an applied force makes a drawing pin goes into the noticeboard and not your thumb: it also explains why a sharp knife is safer than a blunt one when practising culinary skills. There is also another aspect of pressure that relates to forces within a fluid (liquid or gas) and that is … Continue reading Under(water) Pressure
Electric fields
A field, in physics, is a region of space where one object can affect another object without the two objects touching each other. The most familiar fields are gravitational and magnetic but now we need to gain some understanding of electric fields and their shapes. Let's start with a quick recap of what we know … Continue reading Electric fields
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