Boyz and their toyz

It’s been dry today, so the boyz have been out with their toyz. Lots of yellow toyz, lots of moving shit from one pile to another.

They still haven’t worked out they need to excavate the site down 10 feet. 

6 thoughts on “Boyz and their toyz

  1. Browsing suggests a pallet of bricks weights 1-2000kg. Given the density of bricks and the size of the stack on a pallet I reckon the top end of that is nearer; lets say 2000kg.
    E=m*G*h and G=10m/sec^2 as near as damn it, so the potential energy E=400kJ.

    Now actually that’s not much in chemical energy terms. Think – petrol/diesel driven crane, how many times could I lift this on a tankful of fuel? Answer, many, many times; so that potential energy is equivalent to not much petrol/diesel.

    How much explosive? TNT is the easy one, 4.2GJ/tonne (i.e. 1000kg) or 4.2MJ/kg, so the potential energy is the equivalent of about 95g of TNT, about a 4cm cube, a out *half* the charge in a hand grenade. Not that big an explosive charge.

    Actually your problem is not mainly the *energy* – a decent bowl of breakfast cereal, creamy milk and some sugar is probably as much *energy*. You problem is *momentum*. From say 20m again it will hit the ground at about 20m/s with a momentum of 40,000 kg.m/s and your squidgy body isn’t about to stop it without a lot of grief. It weighs a lot more than you do, and accelerates the top of you cowards the bottom of you, with unfortunate results.

    In relatively low velocity collisions like this momentum transfer is the big issue. In very high speed collisions the kinetic energy becomes the big issue (which is why meteor craters are round even in an oblique hit.)

    Physics lesson ends.


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s