Seek help!! 1. Physics Problems !!

The heat absorbed by the object is determined by the mass and specific heat capacity of the object, and when the mass is constant, the smaller the specific heat capacity, the less heat is required to raise one degree; The rapid heating is that the same heat is absorbed in the same time, and the specific heat capacity is smaller, that is, the unit mass is increased1 and the heat absorbed is less.

The definition of the new physical quantity is to explain the qualitative perception of people in life with a quantitative formula, and there are potential prerequisites for the understanding of this sentence.

This expression is incomplete, and should be: under the same conditions, a rapid increase in temperature means that a rise in heat 1 requires less heat absorption.

To help you understand, let's make a hypothesis: absorbing 10 degrees up to 10 degrees means that 1 degree of rise requires absorbing 1 J, and if 10 J rises 1 degree, it means that 1 degree of rise needs to absorb 10 J.

Elevated 1 absorbs less heat, indicating that it raises the temperature more with the same amount of heat. So the heating up is fast.

The temperature of the object changes greatly, and the specific heat capacity is small, which means that the object absorbs less heat for every 1 degree Celsius increase. Therefore, it can be understood that the temperature rises quickly.

Hope.

The same heat source, heating two objects for the same time, one heating up fast, indicating that the specific heat capacity is small, if both things are raised by one, the heat absorbed by the heat capacity is smaller.

This is a matter of specific heat capacity. It's like a thin person (indigestion) and a fat person (with good digestion) who eat. Thin people are easy to be full when they eat (equivalent to heating up quickly), and when both thin people and fat people are full, the thin people eat less than the fat people (that is, when two things with different specific heat capacity raise the same temperature, the one with the greater specific heat capacity is the fat person and can absorb more calories).

I won't talk about those concepts, there are some in the book, I hope you can understand.

Specific heat problems. That is, giving a little energy (heat) can increase its temperature. Then it means that the temperature rises quickly.

Fast heating refers to the same temperature, the time taken is less, with q = cmt, when c and m are unchanged, t is small and q is small.

Solution: 1) Let the weight of each pulley be go, as can be seen from the image, when the object weighs g1=200n, the pulley group.

Target. Mechanical efficiency.

1=50, 1=w has w total = g1h (g1h+2goh) = g1 (g1+2go) = 200n (200n + 2go) = 50

then go=100n

2) As can be seen from the image, when the object weighs g2=2000n, the rope is pulled off, and the maximum tensile force of the rope at this time is f=(g2+2go) 4=(2000n+200n) 4=550n

3) Be noisy.

Pulley block. Target.

Mechanical orange tour effect Xiang Wu waiter rate.

At 80, =w has w total=

gh/(gh+2goh)=g/(g+2go)=g/(g+200n)=80％

The weight of the object is g = 800n

The answer has been provided, so let's not ask. Question 1: Misunderstanding.

There are two ways to understand, you see which one is more convenient:

Explanation 1: Because the two cups are exactly the same, and the balls are submerged in both cases, the height of the liquid rises is the same as that of the V row.

It is known from the inscription: the first liquid is denser, and the pressure increases: p= liquid gh, h is the increased height, and the same. Therefore, the higher the density, the more the pressure increases.

Understanding method 2: First, the buoyancy force is large, and the buoyancy force and the "pressure" of the object on the liquid are a pair of interaction forces, so in the first case, the pressure on the liquid is large, so the increased pressure is also large.

There is also a beaker on the table with a certain amount of water in it, so whether the pressure of the beaker and the water in it on the table is equal to the weight of the beaker plus the weight of the water divided by the area of the bottom of the beaker: this is a correct understanding.

The second question is that the work it does to overcome gravity provides kinetic energy. Just like when we throw a ball upwards, the mechanical energy of the ball is completely given by people, so how much the mechanical energy of the ball increases, how much work people do to it.

In the first question, the pressure of the beaker containing the dense liquid increases greatly (the first beaker) because the height of the liquid in the two beakers is the same, and the volume of the liquid is the same whether it is suspended or sunk to the bottom after being placed in the ball, that is, the height of the liquid in the two beakers increases the same after the ball is placed, and the increase in the pressure at the bottom of the beaker is determined by the increased liquid height and density. i.e. p = gδh, where δh is the height of the increase in the liquid, the δh of the two beakers is the same, so the pressure of the denser liquid increases.

If there is a beaker on a table with a certain amount of water in it, then whether the pressure of the beaker and the water in it on the table is equal to the weight of the beaker plus the weight of water divided by the area at the bottom of the beaker .........Yes.

The second question is that you don't understand it correctly, the title says the work done to overcome gravity, that is, the work done by gravity in this process. (In terms of high school knowledge, when the cicada jumps, the direction of gravity is opposite to the direction of movement, and negative work is done.) The magnitude of gravity multiplied by the height of the cicada jumping is the work done to overcome gravity.

Two identical beakers are placed with two liquids of the same height and different densities, and the same pellet is placed into the liquid in the two beakers respectively, and the pellet is suspended in the first beaker, and in the second beaker, the pellet sinks to the bottom.

So, before and after adding the pellet to 2 of the two beakers, which beaker increases the pressure of the liquid on the bottom of the beaker more, and which beaker increases the pressure of the liquid on the bottom of the beaker more?

Answer] The same ball is put into the liquid in two beakers respectively, the ball is suspended in the first beaker, and in the second beaker, the ball sinks to the bottom, 1= ball.

2 balls. In both beakers, the volume of the pellet is equal, and both are the volume v of the pellet

The liquid level rises at a height of δ h in both beakers

According to δ p= gδh

The change in pressure of the liquid in the first beaker against the bottom of the beaker is δ p1 = 1 gδ h

The change in pressure of the liquid in the second beaker on the bottom of the beaker is δ p2= 2 gδ h

p1＞δ p2

Two beakers with the same beaker so the bottom area is equal to both are s

The change in the pressure of the liquid in the first beaker on the bottom of the beaker δ f1=δp1·s

The pressure of the liquid in the second beaker on the bottom of the beaker changes by δ f2=δp2·s

f1＞δ f2

If there is a beaker on the table with a certain amount of water in it, then whether the pressure of the beaker and the water in it on the table is equal to the weight of the beaker plus the weight of the water divided by the area of the bottom of the beaker.

Answer] Yes! Understood!

The height at which a cicada can jump in 10-3s is known to be 1 10-6kg, and the force used to jump is 400 times its body weight, take g=10n kg. begging

1 The average speed of the cicada from its take-off to its highest point

2 The work done by the cicada to overcome gravity during its jump from the take-off to the highest point

3 The total contact area between the feet of the cicada and the ground is 1 10-6 m2 How much pressure it exerts on the ground when jumping.

Answer] 2 The work done by the cicada to overcome gravity during the jump from the take-off to the highest point.

Your understanding is incorrect, mainly because you don't understand the work done to overcome gravity.

The force does work on the object, some forces do positive work and some forces do negative work, and when the force is in the same direction as the object, this force does positive work on the object.

When the force is opposite to the direction of motion of the object, this force does negative work on the object.

In physics, it is not customary to use the word "negative work", so it is said to overcome this force and do work.

The work done by the cicada in overcoming gravity during the jump from the take-off to the highest point is w=gh

Your first question, levitation, indicates that it is completely submerged in water, so the conclusion is: the water in the first beaker has a strong pressure on the bottom surface of the beaker, and the liquid in the first beaker has a strong pressure on the bottom surface. The specific reason is known according to Archimedes' principle.

The second question is that you are right.

This question is on the verge of learning. The ball accelerates to the left and has a tendency to move upwards along the inclined plane, and the rope has no tension at the critical time; The tendency of the ball to fly up when accelerating to the right, the support force of the inclined plane is zero at the critical time. That's easy to analyze.

1) Accelerate to the left.

At criticality, the resultant force of the supporting force and gravity is horizontally to the left, providing acceleration. It is easy to analyze the resultant force f1=gtan53

Maximum acceleration a1 = f1 m = gtan53 = 4 3g

The acceleration range is 0 to 4 3g

2) Accelerate to the right.

There is no support force at the critical time, the rope tension force and the combined force of gravity provide acceleration, and the resultant force is clearly horizontal to the right. Draw a right-angled triangle of the force to get the resultant force f2 = gcot53 = 3 4g

Maximum acceleration a2=f2 m=

The acceleration is 0 to.

3) Apparently the acceleration has gone beyond the range in (2), and the ball has broken away from the inclined plane and flown up.

It is still the rope tension and gravity that provide the resultant force, now the resultant force is known, that is, g, the gravity force is also g, the other component of the rope tension should be the root number 2g, and the bevel is zero elastic force for the small ball.

I didn't draw the picture, troublesome, come back to me if you have a problem.

s=vo*t+1 2at 2 Note that a=-1 is substituted in the formula.

120=vo*6-1/2*1*6^2

Get vo = 17m s

8cm2=

38dm3=

g total = m total = 392n (

M liquid = 40kg-2kg = 38kg

Liquid density = 38kg

Exactly the density of the water.

Hope it helps.

Container weight + container volume * liquid density * pressure * bottom area gets: 2kg *

Solution: x=1kg l

The liquid is water.

Let the density of the liquid be so ( v+m)g s=p = the density of water (1000 if g = ).

There is one less condition for the question: the electron enters a uniform magnetic field perpendicularly.

Solution: First find the radius of the electron trajectory, which is obtained by q*v0*b m*v0 2 r and the radius is r m*v0 (qb).

1) From the knowledge of triangles, (op 2) r sin is obtained, and the length is op 2r*sin 2*m*v0 *sin (qb).

2) Since the direction of the magnetic field is not given, there are two possible time outcomes.

Probably 1, the trajectory from O to P is less than half a circumference, because the direction of the electron velocity changes 2, so.

The time obtained from the period t 2 m (qb) is t (2 2 )*t 2 *m (qb) (here the unit is radian).

Probably 2, the trajectory from o to p is greater than half a circle, then the direction of velocity changes (2 2), so the time sought is.

t ＝[2π－2θ）/（2π）]t＝2（π－m /(qb)

The specific heat capacity of water is large, and the temperature is difficult to decrease.

The values in the question are unrealistic).

4。The conditions are insufficient, the quality of the ice is not stated. It should be 40g of ice.

840j，40g