How things work
Machines and tools, from first principles.
1:56How does electricity flow?
The light comes on at once, yet each electron in the wire crawls at 0.04 mm a second. What travels fast is the push, shared round the whole loop.
1:46The law of the lever
A lever balances when force × distance from the pivot is equal on both sides. 100 N lifts 400 N, but it must push four times as far: the work is the same.