Gently put a mass m into a container filled with water, and overflow water with mass m from the container, the floating and sinking of the mass in the water is judged correctly as follows: A. If M > m, the block will sink B. If M > m, the block will float up C. If M = m, the mass must be suspended D. If M = m, the mass may be floating I think the question is wrong. D is right. Please give me some advice M> M must sink, but M = m may float or float

Gently put a mass m into a container filled with water, and overflow water with mass m from the container, the floating and sinking of the mass in the water is judged correctly as follows: A. If M > m, the block will sink B. If M > m, the block will float up C. If M = m, the mass must be suspended D. If M = m, the mass may be floating I think the question is wrong. D is right. Please give me some advice M> M must sink, but M = m may float or float

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Mass gravity g = mg, gravity of overflow water mg
According to Archimedes' principle, the buoyancy of the block is equal to the gravity of the discharged water, and F = mg
If M > m, then mg > mg, G > F float, and the block sinks
If M

I have another question. Physical. Online, etc A 4kg object moves at a speed of 6m / s on a circumference with a radius of 3cm. Calculate the centripetal acceleration, angular velocity and centripetal force

Centripetal acceleration a = V ^ 2 / r = 6 ^ 2 / 0.03 = 1200 m / S ^ 2
Centripetal force F = ma = 4 × 1200=4800 N
Angular velocity ω= v/r=6/0.03=200 rad/s

Ask for advice on a physics novel~ Given the initial speed of the arrow and the height and angle of the arrow after hitting the bull's-eye, can we calculate the height of the arrow when it is fired at a certain distance? Calculation formula~

Known conditions: V0, horizontal displacement x (i.e. a certain distance in the question), direction of final velocity (the included angle between the arrow and the horizontal direction after shooting is set as a), gravity acceleration G
Vertical displacement y
Solution 1: time t = x / V0, y = g * t * t / 2, you can find y
Solution 2: vy = V0 * Tan (a), vy * vy = 2gy, you can find y

In physics class, I suddenly thought of a question: since some celestial bodies are hundreds or even tens of millions of light-years away from us, what we see happening to these celestial bodies now is not what happened to these celestial bodies hundreds or even thousands of years ago? Um... Can you elaborate···

That's true.
Because the speed of light is limited, the distance traveled each year is one light year
Well, when the light from a distant planet moves to the earth and is seen by our eyes, in fact, this light has spent a long time in the universe. So your view is correct
What we see is the past. It's really amazing

Ask a physical question Can a parallel circuit also be understood as the whole trunk circuit and the whole branch circuit in series

En. The parallel resistance can be regarded as a resistance connected in series in the circuit. The resistance is the total resistance of the parallel resistance

A physics topic China's achievements in Information Technology (does the Internet count)

Computing. Building the Internet requires technology