Mathematics science problems in junior high school, science problems in junior high school

Since it is a proportional relationship, let y=kx, and bring y=108 and x=36 in.

Elimination. 3.According to the buoyancy principle, buoyancy = the gravitational force of the boat.

Buoyancy = density of gravitational acceleration of the volume of discharge.

So F float = 1030 N.

Gravity allowed to pass through the heaviest ship = 35000 1000 N.

In this way, the gravity of this steamer has not exceeded that of the heaviest ship allowed to pass, so it can pass.

1.Proportional function y=kx

x=36,y=108

k=3 so y=3x

b.Wind erosion should be in deserts and other areas, and the formation should be in the shape of a mushroom, which is different from the smooth shape of a pebble.

c.Glacier erosion should be in the shape of ocean waves.

Does not form the shape of a pebble.

d.Since it has already been said in the title that it is a shallow riverside, it will not be the erosion of the waves, so I chose A

a. The smooth shape of the pebbles is formed by the action of flowing water, so it should be the effect of the current.

And because it's on the shallows by the river.

So you should choose A

A bridge that allows the navigation of ships with a mass of less than 10,000 tons. Can a ship with a displacement of 29,000 cubic meters pass through the bridge? (The density of the river is kilogram meters.)There must be a calculation process).

3.When the boat is in the water, f floats = g

F float = p liquid * g * v row = kg cubic meter * 10 N kg * 29000 cubic meters = 298700000N

g=298700000n

g=mgm=29870000kg=29870tm(max)=35000t

m can pass.

y=3x This problem should be eroded by wind and sun and water.

Is this a multiple-choice question?

The above mention is correct.

AB KOH and (NH4)2SO4 cannot coexist, and ammonia will be generated.

C K2CO3 BA(NO3)2 cannot coexist and will form barium carbonate precipitation.

d FeCl3 is not colorless and is brownish-yellow.

a cacl2 hcl nano3

B KOH HCl (NH4)SO4 [NH4)SO4 + KOH will produce ammonia NH4].

C K2CO3 BA(NO3)2 [BaCO3 white precipitate generation] D FeCl3 NaCl Kno3 [FeCl3 reddish-brown] choose A

What the teacher said is correct, because the systolic blood pressure is 14 kPa, and there is no relationship with atmospheric pressure, so A and B are excluded, and there is no difference between systolic blood pressure and diastolic blood pressure, so only C can be selected, and its value is 14

d ion coexistence means that there is no reaction or the reaction does not produce water, gas, or precipitation.

A H+ OH- reaction to produce water.

The reaction of B H+ and CO3 2- to produce carbon dioxide and water C Ba2+ and SO4 2- to produce barium sulfate precipitate.

d a h + oh- reaction to produce water.

B H+ and CO3 2- react to produce carbon dioxide and water.

Caba2+ and So42- generate barium sulfate precipitates.

1. Chimney cap.

s = square of r = square of *20 = 400

2. Cut the cone along the bus bar and turn it into a fan, and calculate that the area of this fan is equal to the surface area of the chimney, that is, the area of the fan-shaped iron sheet, and the area of the fan-shaped iron sheet (that is, the surface area of the chimney) = 120 square 6 = 2400

The central angle of the circle is 240 degrees, that is, 2 3 circles, then the circle area is 2400 2 3 = 3600, then the radius of this fan-shaped iron sheet = 60cm

The cone is cut along the busbar and becomes a fan, and the area of this fan is equal to the surface area of the chimney.

So s = (circumference of the circle = diameter pi) * bus 2

So s=2400 is pi.

First of all, the height is constant.

Find the new order = total height height of each order = 25 total width of the order = 25

Each step = total width 35=