I kneel and beg for 20 physics calculation questions in junior 2 or junior 3

Now that you know, why don't you answer it.

Write the steps, do you want to write the homework? Or is it for the exam?

Hearing the sound of gunshots, it means that the sound has spread from the starting point to the finish line, and the athletes have already run during this time, but the trembling sparrow is not counted in the results, so the time is undercounted.

t=s/v=100m÷340m/s=

Real results. 10s+

1.Solution: Let the sediment volume be v, then the water volume is (

kg m 3*vm 3+1*10 3kg m 3 (get v=.)

m sediment = kg m 3*

The average sediment content in a flood is 3kg

2 solutions: 1) v water =

V-stone = 3 10 -4m 3-2*10 -4m 3 = 1*10 -4m 3

2) m stone = stone =

Question 1 Average sediment content = a certain volume of sediment content divided by volume (divided by (This is the mass of sand in 100L of sand water.

After finding the mass, divide by the volume and solve it.

Question 2: 1. Divide the water mass by the density to find the original water volume, 2. Subtract the water volume from the total volume to get the total volume of stones.

3. Divide by the number to find the volume of each.

4. Divide the mass of each stone by the volume to find the density.

The first time I helped others solve the problem, I hope you understand the details of the details.

Sand multiplies v sand plus p water times v water equals m total Bring in the value, let v sand equal to m total minus v water or v water equals m total minus v sand to get the volume of water and sand and then find the content in the case of m total, and then enlarge to the required value 2Find the volume of water, subtract the total volume to get the volume of the blank, that is, the volume of the stone, divide by the volume of the stone, get the volume of a stone, and then find the density

Problem 1: Let the volume of sand and gravel be x and the volume of water be yThen 2500x+1000y= x+y= solution, 2500x=3, so the mass of sand and gravel is 3kg, so the final flood sediment content is 30kg per cubic meter.

Solution: Let the speed of the truck be: v kilometers;

Then there is: 27 90 = (27-12) v

Solution: v=50 km.

If the speed of the truck is v km, the time used by the two cars is the same as t hours.

The sedan chased 27 kilometers before it caught up.

90t=27 so t=hour.

vt=27-12, v=50 kmh.

The speed of the truck is x km/h.

27-(27/90)*x=12

When solving the equation x=50 km.

1. Lamp L1 is marked with "6V 4W", L2 is marked with "4V 4W", seek:

1) When two lamps are connected in series at both ends of a power supply, what is the maximum power supply voltage?

2) When two lamps are connected in parallel, what is the maximum trunk current?

3) What is the total power of the above two types of circuits when they are connected in series and parallel?

Electricity, as long as the circuit diagram is drawn. Mechanics is basically buoyancy or something, or a pulley or something.

The resistance of a motor coil is 1 ohm, and the voltage applied at both ends of the coil is 2V, and the current is that the motor works normally.

1.How much power does the motor consume for 1 minute to work normally?

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