How does a winter jacket keep you warm while a cold winter day and Why .
Please help me

In colder weather, people usually wear coats when going outside. Coats keep us warm because of the material of the coat. Our body supplies the heat, and the material helps to trap body heat and keeps the heat from escaping into the air. This is what keeps us warm.

since you're a real machine, your ama is always less than your ima, because you can never totally eliminate friction.

r=rho l/a where a is the area, l is the length and rho is resistivity so the greater the area the lesser the resistance thats why the earth pin is thicker bcos current follow the shortest path, so less resistive .