Ask for high school physics multiple choice questions and high school physics multiple choice questi

1.First of all, it is necessary to understand the conservation theorem of mechanical energy, in the case that only gravity and spring force do work on the object, the kinetic energy and potential energy of the object can be converted into each other, and the total amount of mechanical energy of the object remains the same. This conclusion is called the law of conservation of mechanical energy.

At the beginning of this question, the mechanical energy is mgh, and only gravity does the work, so there is conservation of mechanical energy in the whole falling process, that is, it is all mgh, so the moment of landing is also mgh. As for not adding 1 2mv squared, it is because the gravitational potential energy at the time of landing is negative, and the mechanical energy is the gravitational potential energy plus kinetic energy, and the gravitational potential energy plus kinetic energy will be mgh at this time.

2.Pick D. From the kinetic energy theorem, that is, the work done by the resultant external force is equal to the amount of change in kinetic energy, mgh=1 2mv'*v'-1 2mv*v, since h is the same, it follows that v' is also the same.

1 b is conserved according to mechanical energy.

In the beginning, the ball only has gravitational potential energy = mg(h-h).

Therefore, the mechanical energy at the moment of landing is also mg(h-h).

2 d: First of all, the question misses a sentence: the three balls should have equal masses.

Also according to the conservation of mechanical energy.

The kinetic energy and potential energy of the three balls are equal at the beginning.

So the mechanical energy of the three balls is still equal when landing.

Question 1 selects c Mechanical energy is the sum of potential energy and kinetic energy, and there is no direction.

Question 2: Because the three balls are the same, and they are still at the same height and at the same velocity, and all the potential energy is converted into kinetic energy when landing, the velocity of the three balls when they land is the same.

It's very simple, choose D for the first question

Question 2d

The topic is very unclear... If only it were clearer, it would have been done.

Mechanical energy = gravitational potential first lease imitation energy + kinetic energy = mgh +

bThe increase in the mechanical energy of an object is the work done by an external force21

From this, we can see that C is the correct answer.

11.At the beginning, when f is greater than the f given by the spring, any acceleration motion is made. f-f=ma, f increases, a decreases.

When f=f, v is maximum, and a=0. When f is less than f, the spring continues to compress, f-f=ma, f increases, a increases, do a deceleration motion, decelerate to zero, and the spring compresses to the shortest. From this, we can see that A is wrong, B is wrong, C is right, and D is wrong.

12.According to "**substitution": mg=gmm r2, we can know that g'=

Finding the derivative of s is the instantaneous velocity s'=v=6t2, when t=2 is brought in, v=24;Bring t=0 into s=10+2t3, s1=10, bring t=2 into s=10+2t3, s2=26, and the average velocity is (s1-s2) 2=8Pick D.

Instantaneous velocity is the velocity of a point, whereas average velocity is the velocity of a period of time. The two are only equal when moving at a constant speed or at a constant speed.

14.Let the angle between the rope and the horizontal plane be &

To m: mg=f

For m: mg=fn+fsin&;f=fcos&.

Smooth on the wheel: (m+m)g=fn+f'

decreases, so fn increases, f decreases, f'Decreasing from this shows that A is wrong, B is right, C is wrong, and D is wrong.

Is it all the choice?

Mass divided by density calculates volume.

m^3＝1cm^2

In addition to the oil droplet diameter of 10 -10m to get b

Gram oil, the volume is 1 cubic centimeter, according to several options back-calculated, the thickness corresponds to: 10 6, 10 -8, 10 -10, 10 -4 cm, obviously the fourth option is more reliable, so the correct option is: d

You're so good, all three of you are different.

Obviously, don't be too dead to do the question, don't count it.。。。

v=m p, the molecular radius is of the magnitude of 10 to the minus tenth power, and the calculated volume is the base area multiplied by the height, and the area can be known to be 10,000 square meters.

The rising volume is the same, the work done by the outside world on mercury is equal, and the potential energy of B is smaller than that of A.

The work done by the outside world on the water chaos Hutong silver is increased by the potential energy of mercury and the increase of internal energy. Therefore, choose B

1. AC whether it is 1-12 or 12-1, there is a process of acceleration downward direction, that is, weightlessness process, in the process of weightlessness, the support force (pressure) is less than gravity, and the static friction force becomes smaller.

2. Ab, according to Ampere's rule, the magnetic field of the two currents at points A and B is opposite, and if appropriate, the combined magnetic field of the two currents at points A and B may be 0

Option d heat cannot be said to be contained in the object, heat can only be said to be transferred. So AB is wrong.

Heat can only be transferred from objects with a high temperature to objects with a low temperature. It is only related to the temperature difference between the two objects and not to their respective internal energies.

Internal energy is related to mass and temperature. It cannot be said that the internal energy is large, and the temperature is high.

A and D are correct, B and C are wrong.

Temperature has nothing to do with mass, whereas internal energy has to do with quality.

That is, the temperature of an object with a large internal energy is not necessarily high.

This problem has already appeared in junior high school physics.

1. Choose all of them correctly.

Then it is clearly B wrong.

, the capacitance is still 5ufdWrong.