Before you read this, I suggest you read posts 16.12 and 16.13. When we push or pull something we change its motion by exerting a force on it (post 16.13). Now suppose I’m holding an object. The object is not moving (in my frame of reference). But if I stop holding the object, it drops.… Continue reading 16.16 Gravity

I’ve met a lot of people who don’t try to understand scientific ideas because they are “too difficult” or “boring”. But if you’ve been following this blog so far, I hope that you agree that there is nothing difficult about the ideas I’ve used so far. It is possible to explain them in simple English.… Continue reading 16.15: Science education

Have you ever noticed that car wheels sometimes go the wrong way round in movies and on television? When a car is moving forwards, the wheels go round in a clockwise direction. But sometimes they seem to go the other way round. This effect occurs because moving pictures consist of a sequence of still pictures… Continue reading 16.14 Aliasing – why car wheels can go the wrong way round in movies

I suggest that you read posts 16.2, 16.4 and 16.12 before this. We have seen that an object won’t change its velocity unless it is pushed or pulled in some way (post 16.2). Here we will think about what happens when its velocity does change. To keep things simple, we’ll think about an object moving… Continue reading 16.13 Changes in movement

I suggest that you read posts 16.2 and 16.4 before this. Remember that whether or not something is moving depends on the state of motion of the observer (Post 16.4). So, when we measure movement, we measure it compared to the movement of an observer. Providing the observer is not changing speed or direction, this… Continue reading 16.12 Measuring movement

Appointments of scientists and engineers in industry are often very dependent on the procedures of Human Resources departments. They often place a lot of reliance on results from “assessment centres” that provide general information about a person but not about his or her specialist abilities. This general information may be very useful – but it… Continue reading 16.11 Giving a scientist a job

Of course it won’t! The reason we don’t believe that it will is because we can’t see any reason why it should. We don’t believe things unless we have a good reason. But I would expect people who owned expensive cars to be, on average, healthier than people who own old, inexpensive cars or no… Continue reading 16.10 Will driving an expensive car make you healthier?

I suggest that you read post 16.4 before this. You have probably been taught that the sun doesn’t move around the earth. But you can see that it does! What’s happening? Let’s start with what you can see. This is always a good place to start. It’s much better than blindly accepting what somebody else… Continue reading 16.9 Does the sun move around the earth?

This isn’t a true story. I wrote it to show that we should view predictions based on scientific observations with extreme caution. A biologist decided to study the rabbit population on a small farm. So he decided on a reasonably reliable way to assess the number of wild rabbits living on the farm at the… Continue reading 16.8 Predictions: be careful what you believe

Why should we bother to think about writing numbers? You’ve probably been writing numbers, without any problems, since you were about 5 years old. There are two reasons. The first is that writing very large numbers like 1 000 000 000 000 is a pain – there must be a better way of doing it.… Continue reading 16.7 Writing numbers: it’s not as simple as it seems