The Whin Sill again at Low Force

 

Having previously encountered the Whin Sill on the other side of the hill at High Cup Nick I shouldn't have been surprised to find it in Teesdale where its harder rock causes the waterfall at Low Force. However, it did bring home to me the extent of this intrusion. It ends on Lindisfarne; I found it at Dunstanburgh and also on Hadrian's Wall. 

Calculating the efficiency of my candle

 

I took some results for my candle water-heater and I tried to look up a value for the Joules per gram of candle wax. I found 43kJ and 37kJ so let's say 40kJ per gram. 0.28 grams of wax burned which releases about 11000J. It was set up so a 1 degree Celsius rise in temperature is worth 100J so that means 3140J of energy went into the thermal store of the water. If we are using this candle as a water heater, then the efficiency = 3140/11000 = 0.28. The rest is dissipated to the surroundings as heat and light (heating by particles and heating by radiation in the new parlance). Presumably I would get a higher efficiency if I moved the candle closer, say 2cm instead of 3 cm.

24 cubic centimetres of water

 

We set up this experiment to show that the chemical energy store in a candle empties and the thermal energy store of the water fills. We had the candle 3cm below the tube and we heated for 2 minutes. We weighed the candle before heating and again after. The mass went down slightly showing that the chemical energy store of the candle had emptied. We measured exactly 24 cubic centimetres of water into the tube and measured the temperature at the beginning and end. The 24 cm^3 was chosen because with that volume, the thermal energy store of the water has increased by 100J for every 1 degree Celsius rise in temperature. Not all of the chemical energy from the candle goes to fill the thermal store of the water. Some is dissipated as thermal energy into the surroundings so just by knowing the energy absorbed by the water, we cannot be sure of the actual energy that left the candle. However, I may have a way of attacking this problem and finding the efficiency.

Robin Rigg Wind Farm: bigger turbines

 

Robin Rigg wind farm was visible on the horizon in the sunshine from Southerness Point. I looked up the turbines. Like Watchtree, they are Vestas but this time V90. The serial number refers to the diameter: they have 90m diameter whilst the V47s at Watchtree are 47m. The wind speed for cut in, rated and cut out are the same. These big turbines generate 3MW as opposed to the 660kW of the smaller ones. The swept area of the big ones is 3.67x the smaller (6362m^2:1735m^2). However 660 x 3.67 = 2.4Mw so there is more to extra power generated than just the extra wind energy gathered.

A visit of the centre of England

 

We stumbled upon this whilst out in Sutton Park in the West Midlands. Having been to two rival claimants for the centre of Britain (see this post) I think this is much more likely to be correct since the dispute on the whole of the Britain depends on whether or not you include the Northern Isles. This is probably also done by the centre of mass cardboard model method. And here's what the centre of England actually looks like:

Reaction timer ruler

 

I turned a metre stick into a reaction timer by recalibrating the scale to read in seconds. The idea is that one person holds the ruler vertically level with the top of another person's open hand. When the ruler is dropped, the second person catches it and their reaction time is read from the scale. I used one of the Equations of Uniformly Accelerated Motion to work out the scale division. I used s = ut + 1/2at^2. This reduces to s = 1/2 x g x t^2. Since distance is proportional to t-squared, the linear gaps get bigger.

A lovely film about renewable energy on Eigg

 I'm hoping to visit Eigg and found this lovely film about their ground-breaking renewable energy scheme which involves linking wind, solar and hydroelectric with a battery bank as well.