When work is done on an object, by moving a force through a distance, the object gains energy. As a result, the object might get hotter (gain thermal energy) or accelerate (gain kinetic energy) or be lifted upwards (gain gravitational energy). There is also another possibility; the object could gain electrical energy in the form … Continue reading What is Static Electricity?
Electrical Energy Calculations
The equation for electrical energy is tricky because it contains four components whereas many of the common GCSE equations contain only three components - or can easily be reduced to three because one of the components can be treated as a constant. The best way to handle a four-component equation is to fill-in the values … Continue reading Electrical Energy Calculations
Specific Heat Capacity
Heating a substance can cause either an increase in temperature or a change of state. This is not completely obvious, so let me put it another way; sometimes when we "heat up" a substance it doesn't actually get any hotter. The reason for this is that the energy supplied is being used to break bonds … Continue reading Specific Heat Capacity
Power is the Rate of Change of Energy
There are two booklets available on physbang.com to help you revise the equations that you are expected to know by the end of Y10. These booklets were posted a few months ago (click here to read that post and download the booklets) but it has since been pointed out that one equation is missing: sorry … Continue reading Power is the Rate of Change of Energy
Energy Summary
There are several posts about energy on physbang. You are welcome to explore these posts at your leisure but this one draws some of them together into a logical sequence: it also links to an online worksheet for practising kinetic energy calculations. Although explanations often start by talking about different types of energy, I feel … Continue reading Energy Summary
SP8-9 Forces Doing Work (mini-test)
The first module of Y11 is now complete and to help you prepare for the assessment I have created a mini-test, complete with mark scheme and explanation. You can access the test by clicking here and the mark scheme is here. Work through the questions then check your answers to spot any errors or misconceptions … Continue reading SP8-9 Forces Doing Work (mini-test)
Forces moving forces
The idea of work done can be extremely useful when designing machines that make life easier and sometimes even enable us to do things that are "impossible". For example, it is fair to say that most humans are not capable of lifting masses of a tonne (1000 kg) or more. And yet that is indeed … Continue reading Forces moving forces
Surface Colour and Cooling
In the same way that surface colour affects the rate at which objects heat-up and the maximum temperature that they reach (as discussed here) so too will the surface colour affect the rate of cooling. As before, there is a standard experiment that you are expected to know and a typical set of curves that … Continue reading Surface Colour and Cooling
Surface Colour and Heating
Most people say you shouldn't go out on a summer's day wearing black because you will get too hot. It would be much better to wear white as this will keep you cooler. But is that actually true? We can test this idea using two boiling tubes that have been sprayed to have different surface … Continue reading Surface Colour and Heating
Thermal Equilibrium
Any object that has a constant temperature is in a state of thermal equilibrium. This means the rate at which energy is transferred to the object is exactly equal to the rate at which energy is transferred from the object. In the context of electromagnetic radiation, we can state that the rate at which the … Continue reading Thermal Equilibrium
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