100,000 urgent physics problems no calculations .

This is the chase problem, note the condition: both are in the same position, i.e. when t=0, s is equal to zero.

If you draw an S-T diagram, the uniform linear motion is a straight line, and the uniform acceleration linear motion is a parabola, which is very vivid.

va=vb is the critical condition for the intersection of two lines, when it is greater than it, it must catch up, and if it is less than it, it will not catch up.

The catch-up here should be B catching up with A, that is, they meet again).

That is, suppose that object A catches up with object B

If va=vb happens to catch up or doesn't happen to catch up with va at this time, vb will definitely be able to catch up.

VA "VB can't catch up.

You can ask your teacher, if you want to learn well, you have to know how to ask questions.

Don't be ashamed to ask.

h=at 2 2 , a=2h t 2 = v0t first orange t 2 = v0 qusley

Then bring in the last Shiki Na Xunzi.

v1 ^ 2= 2ah = 2h * a = v0 t * v0/t = v0^2

v1 =v0

T-rays have a smaller frequency than infrared rays and hence have a longer wavelength than infrared rays and are also longer than visible light.

The longer the wavelength, the more obvious the diffraction phenomenon, so C is chosen

The periodic movement of electrons produces chaos (radio waves).

The outer electrons of an atom are excitation to produce (infrared, visible, ultraviolet) and the inner electrons of an atom are excitation (Roentgen rays).

The nucleus is excited and produced (shoot this line).

Therefore, the ray should be produced by the movement of electrons or the excitation of outer electrons.

T-rays have a longer wavelength than X, so they are not as particle-like as X-rays.

I wish you all the best in the college entrance examination, and I hope you can refer to the books yourself, our answers are not necessarily 100% correct, after all, the college entrance examination has been trembling for so many years.

f amp = bilsina =

Direction: If the current is to the west, the force is downward, and vice versa.

Force f=bil=

According to the "left-handed rule" the direction of the force is downward.

Geographically, the South Pole is the North Pole of the geomagnetism, so the magnetic field lines go from south to north. Palm facing south. If the current is to the west, then the four points are to the west. So Damu pointed down. That is, the direction of the force is downward.

h3-h1 is divided by , and the velocity of 2 points is obtained, and the kinetic energy of point 2 can be obtained by using the kinetic energy theorem ek=1 2m 2.

ep=mgh2 is the gravitational potential energy of point 2 and ek=ep can be verified because only gravity does the work in this process.

The velocity at point h3 gt=v (t= using the kinetic energy theorem ek=1 2m 2 where the gravitational potential energy decreases=mgh3 ek=ep, we can verify that the gravitational potential energy is converted into kinetic energy.

x=2+6t²-2t³

The displacement of 4 seconds passed, not the distance, is sought.

Upstairs is all, it turned out to be located at =2m.

t = 4 substitution to get -30

2+30=32m