Friday, July 27, 2018

Am I in trouble over plastic roads?

Apparently I might have dropped my council in it as a result of my innocent enquiry about plastic roads. I wrote a short email to my local representatives to ask whether the council had looked at the use of waste plastic additives in road surfacing and in their reply I was told that:

Several trials around the Country have taken place and the feedback we’ve received so far is that the material has failed due to various such as temperature issues with the mixing of the addictive.  Therefore we’ve decided to hold fire and continue to monitor for further developments.  We do not want to waste tax payers monies on a treatment that may have a shortened design life.
I'm guessing that something is missing between "various" and "such as", but that's how it came. Well, further investigation was required, so I did a search of the internet and couldn't find any related research about failure rates in asphalt using plastic additives. The obvious next step for me was to ask the company about it, and they were let's say surprised.

Reading the LA's response carefully, it seems to imply that the problem isn't with the additive but with the production process. I understand the local authority's need to be cautious, but where's the evidence for failure? If it's the process, then who is monitoring the process in order to get it right? It would be nice if they had responded with some data. All the research I've been able to read points to longer lifetimes for these surfaces not shorter ones. Polymer modified bitumen has been around for some time, but using plastic waste diverted from landfill and recovered from the oceans is new. So the process ought to be within the grasp of industry.

20M tonnes of asphalt is produced in the UK each year and using waste plastic as an additive could recycle 60,000 tonnes of waste that currently goes into landfill. So I think it must be worth pursuing this technology and if there is an issue, then let's see the evidence.

Friday, July 20, 2018

Plastic Roads

Screenshot from the Macrebur website
I often wonder if studying Environmental Science in the late seventies was a decade or two too early. Were we ahead of the curve in a world that was only just waking up to some of the realities of what we were doing to our environment? Perhaps it's still true given that we have an incumbent in the White House who denies climate change, has relaxed EPA targets for the coal industry and apparently would prefer fossil fuels rather than have a wind farm obscure his view across a golf course.

Anyway, I still consider environmental stuff to be an area of interest, and it's clearly something that should concern us all. I keep an eye on the developments of ocean clean-up programmes, and would one-day love to build a near-zero carbon footprint house. Personally I'd like to see all new build housing have solar panels and battery storage, rainwater collection and recycling. Although I've never investigated it, I wonder if that's part of the reason some new developments have ponds and lakes so that rather than sending all the rainwater into the sewer system, it diverts to a water feature.

Back to the point, plastic roads. While we look to reduce the amount of unnecessary plastic used in our day-to-day lives, we also need to think about what to do with the accumulated waste, and that's where plastic roads come into the picture. Some time ago I saw a short news item about a company that was investing in and developing the use of plastic waste as an additive for road surfacing. A recent article in the Guardian reminded me of this and I did a quick search for the company.

It's working. Road surfaces are being laid across the country using a pelletised form of recycled plastic as part of the mix. Not only is this using waste, it's also potentially extending the life of the road surface and of course reducing the usage of raw materials. You can read more about it on the company's website: Macrebur.

I've written to my local councillors to see if my council is exploring the idea and I hope they either are or will be doing so.

Monday, July 16, 2018

Why you can't hit a tennis serve straight down into the opposite service box

Okay, so it's not quite true, but the question is where does your contact point need to be if you could hit down on your serve. All the coaches I know teach an upward strike on the ball. That's not the same as hitting up through the ball, rather it's striking the ball with an upward motion, imparting topspin. The flight of the ball is upward initially but it soon sets to drop towards the service box.

A friend of mine who also plays tennis was telling me the other day that his coach claims you can hit down and attempted to demonstrate doing so. My friend was not convinced that he was in fact hitting down.

Anecdotally I've heard you need to be 6'10" (2.08m) to get near hitting down, so I decided to do a bit of maths to see if I could work out where the contact point needed to be to hit your serve straight down into the service box. I decided to make some assumptions to make the maths a bit easier, and there are some things that to be honest would be too time consuming to include.

So, here we go.

The distance from the base line to the service line (BL to SL) is 18.3m. The net is 0.9m tall. The SL is 6.4m form the net.

A tennis ball is an average of 6.7cm in diameter. For the ball to miss the net by 1cm, the centre of the ball has to be 4.35cm above the net. That means the height from the ground to the centre of the ball is 0.945m. Using some simple trigonometry, the tangent of the angle at the net is 6.4/0.944 (6.77). If the distance from the BL to SL is 18.3m then by using Tan we can calculate the height of the contact point above the BL (18.3/6.77)=2.7m.

So, a ball hit down from 2.7m and following a straight line would miss the net and hit the opposite service line. But there's a snag. Well a few snags actually. First, there's gravity, then there's drag, and of course there's the speed at which the ball is struck. There's also spin that will affect how the ball moves through the air.

Let's deal with gravity first. Gravity will cause the ball to drop as it travels through the air. Gravity causes an object to fall at 9.8m/s2. So, from 2.7m it would take approx. 0.62secs to fall to the height of the net. But it's not simply being stopped, so that doesn't really help!

The distance from the contact point (2.7m above B/L) to the net along a straight line is 12.02m. If you hit a serve at 160km/h (100mph), it would travel that distance in 0.27secs. So, how far does the ball fall under gravity in 0.27secs? Well there's a formula for that:


That works out at 0.36m. That suggests that a ball hit at 160km/h in a straight line towards the opposite S/L will not clear the net!

At its simplest, moving the contact point up by 0.36m would mean the ball would clear the net, and because it continues to fall, it will land inside the service box. So now we have a contact point at 3.06m (10'3").

Drag will slow the ball down as it flies through the air. From what I've read, and again without lots of verified data, it seems as though the accepted impact is that by the time the ball reaches the S/L it has probably slowed down by 60%. As the ball slows down, the impact of gravity will be more significant. In other words it will drop further for each unit of horizontal distance it travels as it decelerates.

If you stayed with me so far (and remember we're trying to keep this as simple as we can), let's assume that the ball slows down at an even rate as it travels. Using those simple assumptions, deceleration will allow the ball to drop 0.045m. Again, keeping things simple, that moves our contact point to 3.11m (10'5").

I'm 6'3" and wth my arm fully extended the sweet spot of my racquet is not high enough to reach that point and create the correct angle. With my normal service action I usually leave the ground, so it's probable that I get my racquet high enough, but only just, to do this, and I need to hit the ball at 100mph to do so! What happens if you slow the serve down to say 80mph? Well I could do the maths, but I'm not going to. The obvious answer is the contact point will need to move higher to compensate. If everything is directly proportional then that could be as much as another 2' of height (60cm). In other words, you'd need to be 8' tall!

The simple conclusion to all of this is that when your coach tells you that you need to strike up through the ball, then trust him/her. They ay not do the maths, but the understand tennis!!

Thursday, July 05, 2018

When faith becomes a platitude

At the end of May I wrote this post in the wake of yet another school shooting in America. I could have written it as a response to the ever increasing knife attacks in London. The only difference is that in the US "prayers and thoughts' get wheeled out as if that's sufficient. That's what bothers me.

I'm angry. Angry and frustrated. I'm angry and frustrated because yet another school shooting has occurred in America and more lives have been lost. But that alone is not all that is winding me up today. It's also the response.

President Trump offers his prayers, a good and proper thing to do, but he can do more. He has the power and authority to create a climate for change. To tell people that it must stop, that more guns are surely not the solution. To tell them that even if they have a constitutional right to bear arms then they need to give up that right for the sake of the nation and in the name of sanity.

Now I know that there are those who profess a faith and subscribe to the pro-gun lobby. I also know that there are those who will tell me that I'm not an American, I don't live in America and it's none of my business. Okay, I understand that, but I'm going to speak anyway because there's more a stake here than national political and identity.

Our faith is being undermined when powerful people invoke prayer without action as a sufficient response. Prayer is not a political tool. Jesus said some interesting things about faith that lacks action. For example, in Matthew 25 we read several parables that follow similar themes. There are the wise and foolish virgins (5 are prepared, 5 are not), the 'talents' or bags of gold and the sheep and goats-a parable about judgement. It is in this last parable that Jesus speaks about the righteous who act 'For I was hungry and you gave me something to eat, I was thirsty and you gave me something to drink, I needed clothes and you clothed me...' If you know the passage, you know that their action wasn't predicated on who was hungry or thirsty, they simply responded with action to the things they saw. The unrighteous see the same things but do nothing.

So why this passage? Well in the first place I'm not about to use it to condemn or judge people. That's not the point. The point is simple. Faith demands action. It simply cannot stand by. It cannot be a platitude.

The gospel remains a powerful message, not only about how we relate to God but also about our responsibility in the world. It has something to say about poverty, about homelessness, about guns and violence, about economics and exploitation, about refugees.

Yes, I'm still angry that powerful people dispense faith without using their power to make a difference.

What wins a tennis match?

With Wimbledon upon us it's time to dust of that old racquet at the back the cupboard and venture out  onto the tarmac of the local park courts. As you sit patiently waiting for someone to finish and the court to become free you begin to imagine hitting glorious forehands and backhands in between screaming aces and delicate drop volleys. The reality of course is rather different as you chase balls around liked a crazed puppy and regularly have to leave the court to fish the ball out of the undergrowth where it disappeared as you skied one over the fence. It's not as easy as it looks on TV.

Tennis is actually a very technical game and to do it well takes skill and practice. A millimetre out at your point of contact with the ball can make a 1.5m difference by the time it lands at the other end of the court, if in fact in lands in the court at all! But once you've learnt the basics and you can serve the ball into the court and rally it can be a lot of fun, and as you develop your skills you will discover the pleasure of hitting the ocassional winner cross-court or down the line as they say. But how many points do you need to win by hitting outright winners? And how many points do you need to win over the course of a match in order to win the match?

Statistically it's surprisingly fewer than you might think. In fact the ATP No 1 over the last 20 odd years usually averages around 55% over the course of a season. Some matches come down to a single point, and there are times when the winner of the match actually wins fewer points than the loser. It's all to do with the way the scoring system works. Whether you win a game "to love" or after four or five deuces doesn't matter when it comes to winning games. It's those points that decide games that are the most important ones to win.

Here's another interesting statistic. Hitting glorious winners is great, but how many points on average are decided by winners? I took a quick look at the stats for three matches at Wimbledon. Here's the data:

Look at the winners as a percentage of total points won. 36, 29 and 14%. A third or fewer of the total points won come from outright winners. So when your coach tells (as mine constantly does) that you need to reduce your error count, they might just be right! There simple truth is that more points are won by forcing an error from your opponent than by hitting winners. It's not a big sample, but it is a pattern most tennis players and coaches will have seen over and over again. 

If this is the case at the highest level of the game then how much more true is it at club and social level? Keeping the ball in play, making fewer errors will probably win you more points and more games and therefore more matches.

Tuesday, July 03, 2018

On Players and Officials

You may have seen this series of images. It's appeared on Twitter and Facebook, posted usually by rugby fans, but not exclusively.

It's a bit disingenuous, in my opinion, to use this particular set of images to highlight the differences between player-offical relationships in the two sports. We all know that footballers surround the referee and argue and abuse the officials over decisions. And yes, rugby is different. Players know that there are sanctions that will be applied if they argue or suggest the referee isn't doing their job properly or fairly. Not so in football. Perhaps that's part of the problem.

My issue with the pictures is that I'm pretty sure Chris Robshaw, for example, isn't shaking Nigel Owens hand because he's just given a decision against England, and that Cristiano Ronaldo isn't arguing with the referee because the game has finished. So we have two different contexts, and setting them against each other doesn't help the argument that there needs to be more respect and self-discipline in football, and that it could learn from rugby.

But rugby is far from pure and saintly. Let's not forget that. More worryingly is that some players are beginning to adopt the worst traits of football when it comes to their relationship with officials.

Something else that needs discussing and addressing is not just the question of role models and how the antics of high profile footballers impacts younger players, but what those younger plays are being taught. Martin Keown was talking some time ago on the BBC about being coached to surround the referee and one wonders whether young players are taught to throw themselves to the ground at the slightest of contacts in order to win penalties and free kicks. Surely such play-acting should never be coached.

VAR ought to be helping officials make better decisions, but it also ought to be letting players know that they will be seen and sanctioned for their actions. It might mean a lot more yellow and red cards are shown for a while, but in the end perhaps some of the simulation we've seen and some of the hostility too will be removed from the game. Perhaps, if a player is guilty of abusing an official or diving or some other form of attempted deception, then it's not they that should spend 10 minutes off the field in a "sin-bin" style approach, but their team's goalkeeper. It might make them think twice about shouting into the face of a referee or rolling around in agony when accidentally stepped on by an opponent (mentioning no names of expensive Brazilian talent).