Before you read this, I suggest you read post 16.24. If you repeat an experiment several times, you will get slightly different results because of random effects beyond your control. For example, if you measure the temperature at which a liquid boils, you may get slightly different results because of changes in atmospheric pressure –… Continue reading 16.26 Normal distribution

Before you read this, I suggest you read posts 16.4 and 16.16. In post 16.16 we met the concept of a gravitational field. Are there other kinds of fields? Yes – two that we encounter in everyday life are the electric field and the magnetic field. Both arise because some objects can have a property… Continue reading 16.25 Electrical charge

Before you read this, I suggest you read post 16.7. A scientist measures the temperature at which a liquid boils and gets the result 80oC. This result is worthless unless we know how reliable it is. We can gain some idea of the reliability from the number of figures given in the result (see post… Continue reading 16.24 Accuracy and precision

Before you read this post, I suggest you read posts 16.20 and 16.21. Power is often confused with energy (post 16.21) and sometimes with force (post 16.13). But power is the rate at which something does work (see post 16.20). This is another way of saying that it is the rate at which something converts… Continue reading 16.23 Power

Ludwig Boltzmann was a successful nineteenth-century physicist who extended the work of James Clerk Maxwell in understanding how the movement of atoms and molecules explains many of the properties of things. He was a professor at the University of Munich and later at the University of Vienna. His greatest success was explaining the nature of… Continue reading 16.22 Science can’t explain everything

Before you read this post, I suggest you read posts 16.13, 16.16, 16.17, 16.19 and 16.20. Most people know that “energy” has a precise meaning in science, for example when applied to nutrition or in the phrase “renewable energy”; unfortunately, several people who I’ve met completely misunderstand what this meaning is. Energy is simply the… Continue reading 16.21 Energy

I suggest that you read post 16.13, post 16.16, post 17 and post 16.19 before you read this one. A force does work when it moves something. If a constant force pushes or pulls something in the direction in which it pushes or pulls, the work that it does is defined to be the value… Continue reading 16.20 Work

16.19 Why do things stop moving if we don’t push or pull them? I suggest that you read posts 16.2, 16.4, 16.12 and 16.13 before this. According to Newton’s second law (post 16.2), an object will keep on moving for ever unless we do something to stop it. To make a moving object slow down… Continue reading 16.19 Why do things stop moving if we don’t push or pull them?

If you are reading this, you must be alive; the device you are reading it on (computer, tablet, phone) is not alive. The science of living things is a specialised subject called biology. You might then expect that we can define what makes something alive. Usually living things are defined to have several characteristics which… Continue reading 16.18 What is life?

Before you read this, I suggest that you read posts 16.13 and 16.16. In science the weight of an object is the force exerted on it by a gravitational field (post 16.16). We measure mass in kilogrammes (post 16.13) and weight in newtons (post 16.13) because it is a force. In everyday English we say… Continue reading 16.17 Weight