Junior high school physics exam questions, junior high school physics exam questions

1.What would happen to our lives if gravity on all the objects on Earth suddenly disappeared? The four students made the following conjectures, one of which could happen was (a).

A man is able to drink water into his stomach.

bThe water will flow downward.

c. Rockets with high thrust are not needed to launch artificial satellites.

dHe who hangs in the air will fall.

2.The following statements about the use of spring dynamometers are correct: (b) a spring scale must be placed upright and must not be tilted

b. Any large force can be measured with a spring dynamometer.

cWhen measuring the force, the direction of force of the spring dynamometer should be along the axis of the spring.

d. You don't have to check if the pointer is at the 0 tick mark before use.

3.The vital activities of each living organism need metabolism, and if the mass of substances absorbed by the living body is m absorption, and the mass of the substances discharged is m discharge, then for our middle school students, we are in the stage of growth and development, and in most normal cases, the relationship between m absorption and m emission is (a).

Suction m row Suction = m row.

Suction m row dIt is impossible to judge.

Question 2: You are wrong.

The first option d is likely to occur abc is again gravitational.

The second option A has nothing to say.

The third option is that most of the teenagers absorb all the nutrients and have a strong absorption capacity.

1c 2a 3a, buddy, it's not good, study hard, college student.

a Parachutes must be equipped to ensure a safe landing on the Moon (there is no atmosphere on the Moon, parachutes are slowed down by the resistance of the air, so parachutes are useless on the Moon).

b A perpendicular line can be installed on the rover to allow for observation of the degree of inclination. (The Moon also has a gravitational pull, so yes)

c A compass should be equipped to determine the direction (the compass is indicated by the Earth's magnetic field, and the Moon has no magnetic field, so it is useless).

d A spare petrol engine can be installed for the rover for emergency use (there is no air on the moon and therefore cannot be used).

The angle may be 30 or 60, and the direction of reflection is different.

There is a convergence effect.

No atmospheric vacuum, no combustion, no optional d, no magnetic field can not be selected c, the compass is the use of magnetic field, such as China's astronauts out of the warehouse in space itself is floating, fortunately, the moon still has one-sixth of the earth's gravity, such a weak gravity can but does not necessarily have to be equipped with a parachute, not optional a. Therefore, choose B

Question supplement: 30 degrees; Convergence.

b Tell me if you have any questions.

A: There is no air on the moon, and parachutes need air to be used.

c There is no magnetic field, and the compass is useless.

dThere is no oxygen, and gasoline cannot be ignited.

degree convergence.

Choose BA weak gravity that the acceleration is very slow, no parachute is used.

c There is no magnetic field, and the compass is useless.

d gasoline engine has no oxygen, it can't be used.

Correct Answer: BA has no atmosphere, i.e., no air resistance, and cannot decelerate.

b Weak gravity, but there is gravity.

c The direction of the Moon's magnetic field cannot be determined.

dNo atmosphere, i.e., no air.

Convergence.

d, there is no atmosphere on the moon, so parachutes cannot be used; There is no magnetic field on the moon, so the compass cannot be used; There is no gravity on the Moon, so the reperpendicular line is useless. I've done this question no less than five times...Dig hahaha....

degrees or 30 degrees of focus.

The first one above says that gathering, and then they all say gathering, and some people say that they gather, and they say that they gather, and if you say it, please have a bit of a physical flavor, and the most formal way of saying it is to focus.

1. The convex lens is convergence, and the concave lens is divergent.

1) Mercury contains impurities.

If the mercury contains impurities, the density of the mercury column will decrease and the mercury column will rise. 2) The measurement method is wrong.

Note when measuring: It is to measure the vertical distance between the highest liquid level of the mercury column and the liquid level of the water tank, not to measure the distance of the mercury column in the glass tube).

Measuring along the mercury tube is the length of the mercury column, 760mm is the vertical height, if the pipe is tilted, the value will be greater than 760mm. So it will measure 770mm

1.Mercury is impure.

2.The local atmospheric pressure is higher than the standard atmospheric pressure.

3.The tube is tilted.

It is possible that a small amount of air may enter the interior, causing a small change in the difference between the internal air pressure and the external air pressure. The teacher should have talked about it in class.

The answer is that the pull force of the BA spring dynamometer on the object is horizontal, and the gravitational force on the object is vertical.

c These two forces are the relationship between the action force and the reaction force, and the magnitude must be equal, and it has nothing to do with the state of motion of the object.

d, these two are just equal in value, and the direction is the same.

A pair of equilibrium forces are characterized by acting on the same object, equal in size, in reverse, and collinear.

B should be chosen. Hope it helps!

A warship at sea reduces its own weight after launching a missile, and it still floats, so buoyancy is equal to gravity, and buoyancy also decreases with gravity, and according to Archimedes' principle, the volume of the displacement also decreases, so it floats, but eventually floats.

Enlargement Moderate floating.

Believe me, it's a very simple question.

Wait, I think this question can be replaced by this, it's easier to understand. A boat floats in the water, there are stones in the boat, and now throw a stone into the water. Will the buoyancy of the water on the boat increase or decrease, will the boat float up or sink or will it always float?

Of course, the boat is floating, you can't lose a stone, the boat will sink, hehe, as for the buoyancy, it should be reduced, when the stone has not been thrown out, on the ship, and the ship is floating, so the stone is also floating, and in the floating state, buoyancy is equal to gravity. The buoyancy of the whole ship is equal to the gravitational force of the boat plus the stones. But if it is thrown out, the stone is denser than the water, so the stone will sink, and when it sinks, the buoyancy of the water will be less than the gravitational force.

Therefore, the buoyancy of the boat decreases, and the boat will rise relative to when it does not lose stones, because the buoyancy decreases, and the volume of water discharged will be less, so it will rise. Hehe, philology is not very good, and there is a bit of a problem with the language organization. The buoyancy chapter is not very easy for me to learn, and I remember that I scored more than 20 points in one test

Buoyancy decreases, floats .

It will float because its density is smaller than that of seawater, which is determined by the fact that the battleship is hollow, although the battleship is made of iron, but its overall density is calculated by =m v, and the mass of iron that makes it is certain, but because it is hollow, the volume also increases greatly, and the overall density is smaller than that of seawater, so it floats.

During the launch of the missile, the battleship is affected by the impulse of the missile, and the buoyancy of the battleship increases first, and finally, because the missile leaves the battleship, the total mass of the battleship decreases, and the buoyancy decreases, but it will definitely float.

The buoyancy will decrease because he is floating on the sea, so the buoyancy is equal to gravity, and after launching the missile, the gravity decreases and the buoyancy decreases.

Air) vg (air quality inside the iron ball) = p (water) vg

Buoyancy is equal to gravity, and the formula for the volume of the ball is to calculate it on behalf of you, and you try to mix it.