# Question Video: Health and Safety in Experiments Physics

Which of the points on the graph of risk and hazard severity best corresponds to the activity of measuring the gas pressure required to rupture a thick steel container?

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### Video Transcript

Which of the points on the graph of risk and hazard severity best corresponds to the activity of measuring the gas pressure required to rupture a thick steel container?

Okay so this question, we can see that we’ve got a graph that shows risk and hazard severity on its two axes, and we’ve got five points A, B, C, D, and E at various locations on the graph. So first of all, what do risk and hazard severity even mean well? Risk is the perceived probability of something going wrong. In other words, how likely does the scientist think it is for something bad to happen in the experiment? So that’s risk. And hazard severity is how bad the consequences are going to be if something does go wrong. In other words, let’s say that for example we’re in bed and holding an iPad up above our face watching a video on the iPad. Now in this case something does end up going wrong, and the iPad falls on our face. What’s the hazard severity in the situation? Well, we’ll probably hurt our nose and have a bruised ego. But apart from that, it’s not very severe hazard. We’re not likely to break any bones or cause any serious damage, whereas consider a tightrope walker walking off a really thin rope about 50 feet above the ground.

Now this tightrope walker were to fall off the rope, then the severity of the hazard will be very high because it’s likely that they would probably injure themselves and maybe even die. So the iPad in bed falling on a face is an example of low-hazard severity, whereas the tightrope walker falling off from their rope is an example of high-hazard severity. Now coming back to a graph, we can see that as we move towards the right, the risk or the expected probability of something going wrong increases. And from the vertical axis, we can see that as we go up, the hazard severity increases. Now we’re trying to work out the risk and hazard severity of an experiment that measuring the gas pressure required to rupture a thick steel container. Now a thick steel container is quite difficult to rupture. So immediately we can think that it’s probably gonna take a very high gas pressure in order to rupture that steel container.

Now high gas pressures are quite dangerous, because in the event that something does go wrong, there could for example be an explosion. And to top it all off, because we’re talking about a thick steel container, that explosion could basically send bits of steel flying everywhere. Depending on how large the container was, this steel could either get embedded into a scientist if they were not careful. Or if it’s a very large steel container, then bits of steel flying around could actually kill somebody as well. Therefore, we can say that the hazard severity is very high. So we’re looking at sort of the higher regions of the graph. So now let’s consider the risk in this situation. Well if we’re trying to measure the gas pressure required to rupture a thick steel container, the only way we can find this out is to actually increase the gas pressure until the container ruptures, because otherwise how else will we know.

We can do some calculations based on theory, but our theories might be incorrect. So the only way to find out the pressure required to break through the steel container is to actually break the steel container. And once we do break the steel container, it’s difficult to predict which way things will fly off in the explosion. Therefore, the probability of something going wrong is actually fairly high. First of all, there definitely is going to be some sort of explosion, so that in itself increases the risk massively. Secondly, because it’s a steel container that we’re talking about, this increases the risk even more, because now not only do we have a gas explosion, but we’ve got a bit of steel flying around as well. Therefore, we’re gonna have to look at the high-risk parts of the graph. And so the point in the graph that has both a high-hazard severity and a high risk is the point B. Hence, this is the answer to our question. Point B best corresponds to the activity of measuring the gas pressure require a rupture at a thick steel container.