The master of physics helps, and the master of physics comes in to help

1 For every man is hidden in his house. No one came out.

2 The principle is the same, but the development of science and technology is just that, mosquito coils have a smell, and the electric mosquito coils invented by scientists are not smelly and fragrant.

The fluffy structure of snow has the effect of absorbing sound waves, to be more precise, honeycomb structure.

Maybe the box will make a sound that is beyond the range of human hearing and is within the hearing range of mosquitoes.

1. The pulling force is equal to the resistance (300 times equal) 30N, the pressure is equal to the gravitational force 300N, and the pressure is equal to (300 divided by.

2. How fifteen fourteenths of the volume is immersed in water.

3. In the gravity of the moon (69*10*one-sixth) 115n, the high jump should be six times!

h/sin30= =>t=2s

Gravity: mgt=40

Supporting force: mgcos30*t=20 root number 3

Net force: mgsin30*t=20

The electrostatic field is a conservative force field (like a gravitational field). The work done by a conservative force field is only related to the beginning and end positions, not the path. That is, the charge is moved back to the starting position by moving it in an arbitrary path, and the work done is zero.

For this diagram, the middle is an isolated point charge, then the circle centered on it is its equipotential surface (the property of the electric field of the isolated charge), which is where the electric potential is the same, according to w=qu, the potential difference u is the same, the amount of charge q is certain, so the work is the same. In addition, it can also be seen in this way, the starting position a is certain, the end position b, c, d, the electric potential is the same, that is, the end position is the same, the conservative force does the work, the beginning and end positions are certain, and the work is certain. (understood in relation to the gravitational field).

Points b, c, and d are on the same equipotential plane! You can see what the isopotential surface of a charge looks like on the textbook!

As many as possible, points b, c, and d are on the same equipotential plane, so they have an equal potential difference with point a. When moving, the work done by the electric field force w=qu is equal.

Do as much work, of course.

Because the work done by the electric field force is equal to the decreasing value of the electric potential energy, and in this problem, the three points b, c, and d are located on the same equipotential plane, that is, the potential difference from point A to each point is equal.

So the electric field force does as much work as in this process.

Apply the law of conservation of momentum.

01 We set the time to 1s

ft=mv to get m=100kg

02 f=ma

a=5m/s^2+10m/s^2=15m/s^2f=ma=7500

ft=mv gives m=150kg