How to use the lever principle of tweezers? How to draw the schematic diagram of its power and resistance? Also, which direction is the schematic diagram of the power of pulling nails with a hammer? So does the direction of power and resistance not have to be opposite or opposite?

How to use the lever principle of tweezers? How to draw the schematic diagram of its power and resistance? Also, which direction is the schematic diagram of the power of pulling nails with a hammer? So does the direction of power and resistance not have to be opposite or opposite?

The fulcrum of tweezers is the intersection of the two arms at the last end. The hand exerts power downward and the clamped object exerts resistance upward
The direction of hand moving the hammer is the direction of power
(you mean the claw hammer?) the lever in this picture is actually a broken line, not a straight rod, so there is no opposite problem. The power and resistance only need to keep the lever not turning in one direction (this is very important for learning leverage)
Got it?