We visited Durham Cathedral today to visit the bells. Everyone we met was really nice. Here's a picture of the tenor bell, the heaviest. It's 28 cwt (that's short for hundredweight) - bell ringers like old units. 1 cwt is worth 50kg (2sf) in the UK, so the mass of the bell is 1400kg, which is 1.4 tonnes. That might be the mass of a small car. It took two people to ring the bell round so that it was upside down like this, but one person can them comfortably ring it because of the large size of the wooden wheel to which it is attached. The bigger radius means that the required moment to turn the bell can be achieved with a smaller force, since moment = force x distance.
Here are some clappers. The middle one was biggest. It was about 1m long with a 5cm diameter. Cross-sectional area is pi x r-squared so about 0.002 square metres. The volume is then 0.002 cubic metres, with the mass of the ball to be considered as well, of say radius 10cm, giving an additional volume of 0.0005 cubic metres. Total volume is 0.0025 cubic metres. I think bells contain a lot of copper, which has a density of 8920 kg per cubic metre, giving the clapper a mass of 22kg. This must be an underestimate! I'll go and think about it.
Here's the view down through the hole in the trapdoor to the ground floor. This is what 60 metres looks like!
Here are a couple of views from the top of the tower to show how high we were.
