Physics masters, please enter! High school freshman! Hurry, hurry

1. V 2=2GH V=GT T 3 V = V-GT=2 3V V 2=2GH solution H=4 9H

2. Let the displacement velocity in the middle be v, then there is v0 2-v 2=2gh for the first half of the displacement, and v 2-0=2gh for the second half of the displacement, and the simultaneous solution of v = under the root number (v0 2 2).

3. Calculate the velocity at 15m, and 20 2-v 2=2gh (h=15m) is solved to obtain v=10m s

Let the upward direction be positive, and we have the velocity equation 20-gt=10, which is solved to t=1s or t=3s

1/2gt^2=h 1/2g(2/3t^2)=4/9h h-4/9h=5/9h

VO 2-VX 2) 2G = VO 2 4G VX = 1/2 of the root number multiplied by VO

vo^2-vx^2)/2g=15 vx=10 t=(vo-vx)/g=1s

1) H=V0*T2.

v0=2h/t

s=v0*t/3-1/2g(t/3)^2

Substituting v0 into the calculation yields the result).

2)v0^2=2gh

vt^2-v0^2=-2g(h/2)

The result can be obtained by solving the above two equations simultaneously.

3)s=v0t-1/2gt^2

Substituting the data, there should be two results, both correct, one is the time taken to ascend to 15 meters, and the other is the time taken to descend to 15 meters.

4 ohms. First, find the total power of the motor = iv = 5 * 110 = 550 watts;

Then find the power done to the object = gravity multiplied by speed = 50 * 10 * watts.

550-450 = 100 watts is the loss of the motor resistance, that is, the heat generated by its resistance, that is, the copper loss.

Then resistance r = power square of current = 100 25 = 4 ohms.

Using the law of conservation of mechanical energy, find the velocity of the ball to the lowest point.

ek0+ep0 = ek

1 2*MV0*V0 + mg*2L = 1 2*MV*V, with v, find the tension t of the rope

t - mg = mvv/l

t = mvv/l+ mg

Physical wolf pack.

No external force does the work done by the law of conservation of energy. So when the ball reaches its lowest point, the velocity is still the velocity at the beginning. The pulling force of the rope is equal to the gravitational force + centripetal force. Centripetal force = m*v 2 l, v = 2*g*l

Tensile force = 3*m*g

u/d=e

f=eq=uq/d= * / = n

w=uq=( / 2 ) = j

1) Electric potential = e q This is the formula for the field strength that people use point charges or other charges to detect a point, not a determining formula.

2) I don't understand the problem, look at the position of the ball in the two pole plates, the potential difference is evenly divided at this distance, the electric potential gradually increases from the negative plate, look at the percentage, I have been using this method to calculate back then, and I have tried and tested.

Did you misremember?

In order to generate an electric field, there must be a potential difference, u=ed (the distance between the plates d) is constant.

In the middle, the difference in potential is only half at the middle position.

The electric potential is equal to ep q

It is half of the potential difference according to UAB = ed = u d'*dd'=2d

UAB is the potential difference between the two places.

Acceleration means that the direction of acceleration is in the same direction as the direction of motion, while deceleration is the opposite.

So the acceleration direction of acceleration is the same as that of deceleration and deceleration of descent, and the acceleration of acceleration and descent is the same as that of deceleration and ascent.

It is found that weight loss means that the acceleration of movement is in the same direction as the acceleration of gravity, which can be understood as a part of the acceleration of gravity into the acceleration of movement, so the person's "weight" is reduced.

Therefore, the correct BC is directly determined by the direction.

It's not weight loss, it's less support.

Let the person's weight be mg, f = 80% mg =

f = direction down).

So it's acceleration down or deceleration up i.e. BC

Of course, it's bc, b, because there is an acceleration drop, f=ma, so it becomes lighter.

c, because you start with a lot of speed, and then start to slow down and go up, taking the same force.

Explain that the support force of the scale to people is, people are subject to gravity and support force, by Newton's second law, the acceleration of people A = (, the direction is downward, the acceleration of BC is downward, and AD is upward, so BC is chosen.

Why is the first year of high school so difficult?

Could it be. It's mg?

This can be decomposed by gravity, and if the inclination angle of the inclined plane is a, the pressure is cosa*mg

The object is subjected to 3 forces.

Gravity pulls the supporting force.

If the inclination angle of the inclined plane is a, then the pressure is mgcosa

e=hc, the total energy produced by the photoelectric effect ek=e-w can be calculated

w is the work done by the electron to overcome the binding force.

This work is the same.

So the answer to the landlord's question is to use the difference between the total energy produced by the two wavelengths of ultraviolet light plus the maximum kinetic energy of the photoelectron produced by the ultraviolet rays.

ekm=hv-w, where: =c v

Substituting the values from the above two equations gives ekm = ev