Junior 1 Physical Science Please answer in detail, thank you 13 19 14 17

An object weighing 50 N is stationary on a rough horizontal plane, and if it is pushed to the right with a horizontal pull force of 5 N but is not pushed, the friction on the object is 5 N and the direction is to the left. If the horizontal thrust to the right is increased to 10 N, and the object is moving in a straight line at a uniform speed, then the amount of friction collected by the object is 10 N, and the direction is to the left. If the horizontal thrust to the right is increased to 15 N, the amount of friction collected by the object is 10 N.

: It belongs to static friction and is equal to the applied external force.

2。Horizontal to Left: The two forces are flat and horizontal, and the direction is opposite to the direction of the thrust.

Uniform linear motion" means that the external force experienced is 0, i.e., the frictional force thrust 10n4. Horizontal to the left: Reason is the same as 2

The magnitude of friction is only related to roughness and pressure, and has nothing to do with thrust, which can be made to move in a straight line at a uniform speed, and its friction force is 10N according to the horizontal and horizontal of the two forces

Brother Tai, this is the question of the third year of the people's education version!

1) (2) The horizontal force is balanced, so the two forces in the horizontal direction, thrust and friction, are a pair of balanced forces, then they are the same magnitude and opposite to the direction.

So. 1) 5 Ox, to the left.

2) 10 Ox, to the left.

3) Imbalance, which would have been impossible to calculate. But the previous title tells us "......Increase to 10 N and the object is just ......"So we know that the sliding friction is 10 N. The sliding friction does not change when the contact surface and positive pressure of the same object do not change.

So. 3) 10 Ox.

5 Left 10 Left 10

1。Since the balance of the forces is obtained, at the beginning there is no push, and the frictional force is greater than equal to the applied external force.

2。Linear motion at a uniform velocity can be obtained that the force has reached equilibrium, that is, the frictional force is equal to the external force.

f=un from which the coefficient of friction = can be calculated

I forgot that it seemed to be this.

1.The direction of the friction force is to the right, which is the static friction force, the magnitude of which cannot be determined, but is less than the maximum static friction force.

2.The size is 10 N and the direction is horizontal to the left.

3.Or 10 Ox.

5n, to the left;

10n, to the left.

10nHow do I remember when I was a freshman in high school, I did this kind of question...

Topic: Separating sugar water from water.

Preparation: Alcohol lamp Evaporation dish Iron rack beaker Glass rod method: 1 Place the evaporation dish on the iron rack and pour the mixture of sugar water and water into the evaporation dish.

2 Heat with an alcohol lamp, stirring with a glass rod while heating until a white sugar substance is produced, heat for another 1 to 2 minutes to remove the alcohol lamp and extinguish the alcohol lamp.

3. When the evaporation dish cools, pour the sugar into the beaker and stir with water, which is sugar water.

It doesn't seem right, it's a bit messy.

According to Archimedes' law, the gravity of the water discharged by the block is equal to the gravity of the block, which means that the gravity of the water in the volume of 3 4 blocks is equivalent to the gravity of the block of 1 block of wood drainage = water. Drainage, g wood block = wood. Block.

Then g drains = g block, g = g, v drains = 3 4v block, wood is equal to 3 4 water, we know water = , then wood is equal to. Respect.

You can count it yourself, I can't figure it out, it's too difficult!

1 In the same liquid, the larger the volume of the liquid discharged by the object, the greater the buoyancy force.

2 Acetic acid bacteria do not form a nucleus (yeast is a fungus, acetic acid bacteria are bacteria) 3 (1) There is a lack of conditions, and it is necessary to know the total weight after carrying two people.

If the total weight is 5000N, then F float = 5000N, so V row = cubic meter, so the total volume is cubic meter.

2) The use of lightweight, environmentally friendly and corrosion-resistant materials to make the body can reduce fuel loss and prolong the service life of the car.

The answer should be B: Minus.

The working principle of a spring dynamometer is:

Hooke's Law; Within a certain range, the elongation of the spring is proportional to the tensile force experienced.

The pointer on the spring dynamometer used in the laboratory is located in the lower part of the spring, and the so-called zeroing is just to align the zero scale of the dial with the pointer;

Therefore, the scale on the spring dynamometer can be understood as measuring the elongation of the spring.

This is like taking a scale to measure the length of an object, but the 0 scale is not aligned with one end of the object, but a non-zero scale is aligned with one end of the object, so the reading at the other end is subtracted from this scale to be the actual scale.

The argument d doesn't make logical sense.

Of course, if the structure of the spring dynamometer you use is different from the spring dynamometer used in the laboratory, then it is a different story.

Sphere volume v=m p=(

In water: the ball sinks to the bottom, buoyancy f=p water * vg = (1kg dm 3) * (1dm 3) * 10n kg) = 10n

Put it in mercury:

Iron is less dense than mercury, floating, buoyant f'= gravity mg=

Select B, the light passing through the focal point can become a parallel light through a convex lens.

A wrong, I didn't talk about it.

c and d are wrong, in order to make the concave lens come out of the parallel light, it must be directed to the imaginary focus incidence, which cannot be achieved by small bulbs.