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