Answer:
2.61 J
Explanation:
Since potential energy U = mgy where m = mass of object, g = acceleration due to gravity = 9.8 m/s² and y = height of object above the ground.
Now for the coffee mug, m= 0.422 kg and it is 0.63 m on a table, so it is 0.63 m above the ground. Thus, y = 0.63 m.
We compute U
U = mgy
= 0.422 kg × 9.8 m/s² × 0.63 m
= 2.605 J
≅ 2.61 J
So, the potential energy of the mug with respect to the floor is 2.61 J
(a) We can find the current flowing between the walls by using Ohm's law:

where

is the potential difference and

is the resistance. Substituting these values, we get

(b) The total charge flowing between the walls is the product between the current and the time interval:

The problem says

, so the total charge is

The current consists of Na+ ions, each of them having a charge of

. To find the number of ions flowing, we can simply divide the total charge by the charge of a single ion:
You'd get an extra 40/60 of the energy, or 2/3. Multiply 5/3 by the required energy to get the actual consumption.
AS
work done =W = F.d = F d cosФ (Ф is angle between force F and displacement d) If a body/object is moving on a smooth surface (friction-less surface ) .There is no force acting on that body. F=0 so W=FdcosФ= (0)dcosФ ⇒ W=0
Now if a body is facing some amount of force but under the action of force there is no displacement covered. d=0 so W =FdcosФ= F(0)cosФ ⇒W=0
example: A person is applying a force on rigid wall but wall remains at rest there is no displacement occurs in wall.
The third term upon which work done dependent is angle between force and displacement i.e Ф. If Ф=90° then W= FdcosФ= Fdcos90⇒ W=0 ( as cos 90°=0)
Different elements require different levels of energy to make or break a bond