What are adjectives, nouns and verbs in Chinese How to draw the arm of force in physics? How to be a laborious lever? How to increase the friction and pressure, reduce the friction and pressure? How to calculate the pressure and speed?

What are adjectives, nouns and verbs in Chinese How to draw the arm of force in physics? How to be a laborious lever? How to increase the friction and pressure, reduce the friction and pressure? How to calculate the pressure and speed?

Because it is inconvenient to draw a picture, we draw a picture together: there is a horizontal thin rod (lever), a (hanging in the air) at the left end, B (the bottom of B contacts the ground) at the right end, and a point O in the middle is the fulcrum (the fulcrum is not guaranteed to be in the middle)
From the title: VA = 1 cubic decimeter, and ρ a = 3 * 1000kg / m3 = 3kg / cubic decimeter, so Ma = 3kg, GA = ma * g = 30n;
VB = 8 cubic decimeter, and ρ B = 2 * 1000kg / m3 = 2kg / cubic decimeter, so Ma = 16KG, and GB = MB * g = 160n;
The pressure of B to the ground is 2500pa, and the contact area between B and the ground is s = 4 square decimeter = 0.04 square meter, so the pressure of B to the ground is F1 = 2500pa * 0.04 square meter = 100N, so the tension of the rope above B is 60N;
It can be seen that the pull up force of a rope is 30n, while that of B rope is 60N, so the ratio of the left arm OA and the right arm ob of the lever is 2 ∶ 1;
Now immerse a completely in water, and the buoyancy (upward) is 1 cubic decimeter. The weight of water is 10 n. in order to balance the lever, an upward force should be added at B end, which is 20 n (inversely proportional to the arm of force). In this way, the supporting force to B increases from 100 N to 120 n (that is, the pressure of B to the ground is 120 n). Therefore, the pressure of B to the ground is 120 n / 0.04 M2 = 3000pa