Physics problems, ask for the solution T T more detailed

1. Electric energy consumption = 40x100x2 1000 = 8 kWh.

2. Definition of resistivity: =rs l r= so =6*ohm·mm² m Where:

Resistivity is a physical quantity used to express the electrical properties of various substances. The resistivity of a wire made of a material that is 1 meter long and has a cross-sectional area of 1 square millimeter is called the resistivity of this material.

1. 2 times 100 times 40 = 8000 kWh.

2. r = resistivity = 6 multiplied and divided.

Question 1: w=; Question 2: First, the resistance is obtained from the current and voltage, r=, and then there is the resistance formula: r=kl s (k is the resistivity), and the data is brought in to get k=6*

Greater than Because the initial speed is the same, the greater the mass, the greater the kinetic energy of the trolley, the more work done to overcome the resistance in the process of stopping, and in the case of the same resistance, the longer the distance of the movement (or the mass is large, the inertia is greater, and the distance required for the trolley to stop under the same conditions is longer).

Irrationality! (It's definitely unreasonable to ask so) Because of the different pressures, the friction of the car is different, and it cannot meet the control variables, so it is unreasonable. (f=g=f) because of constant velocity).

This question is the original question of the high school entrance examination.

Greater than the gravitational force of the object, the greater the inertia.

Reasonable: Because of the large mass and large inertia, it is said that in the same situation, the distance used by the large car to stop is longer than that of the small car.

Ditto: This condition should be problematic Ignoring the fact that the specific heat capacity of the water is 4200

q=cmδt

The quality of water in the juice A requires the mass of Bing Nianqi block b the mass of juice powder ( the specific heat capacity of the juice powder c the specific heat capacity of the mixture is C mixed = (M1C1 + M2C2) (M1 + M2) Substituting this formula.

Doesn't the specific heat capacity of the juice change when ice cubes are diluted?

When work is done on the gas in the case of adiabatic, the temperature of the gas must increase The final pressure is the same, the mass of the gas is the same, according to the gaseous equation, v'>v gaseous equation: PV t=p'v'/t'

Solution: It is known that the mass of the car is m, the maximum power is p, the acceleration is a, the time of motion is t, the distance of motion is s, the original speed v0 = 54km h = 15m s, and the later speed vt = 114km h =

Since there is no mention of resistance or friction factor, we do not consider it.

According to the formula of acceleration motion vt 2-v0 2 = 2as

Because the traction force of the car = mass acceleration, there is pt s=ma, and then according to the acceleration motion formula vt 2-v0 2=2as

Yes: 163 746) t [(.]

So. t=2.Mass = Momentum Velocity = 4875 39 = 125kg

3.Fortunately, you attached the English title, and the quality of the package was not said in the Chinese translation, hehe.

The original state is stationary, let the direction of the package fly out is positive, and the velocity of the ship is v, which can be known according to the conservation of momentum

The momentum of the package - the momentum of the whole made up of the man and the boat = 0, so there is.

v=4.Because the two cars are exactly the same, the center of mass of the system is in a straight line in the northeast direction of 45°, in the velocity triangle formed by the two cars, so the speed of the two cars is v, then there is:

v 2 + v 2 = 50 2, so.

v=5.Because of the inelastic collision, the kinetic energy is not conserved, according to the conservation of momentum, let the velocity of the bullet after the collision be v, the sum of the momentum of the bullet and the wooden block before the collision = the sum of the momentum of the bullet and the wooden block after the collision.

That is: (22 1000) 200+0=(22 1000)v+1

Get: v=-81m s and the direction is left.

Don't think that foreign questions are difficult, these questions are based on the premise of understanding the formulas and unit conversion, and do not put obstacles in your way, if you haven't learned these formulas, go to the reference book.

According to the principle of the equilibrium intersection of three forces, the two diagrams A and B are both plane intersection force systems, so the equilibrium condition is: f(x)=0 f(y)=0

(a) fax=cos45 F to the right; fay=fby= sin45 f up;

b) fax = cos45 f, to the right, fay = sin45 f up, fb f 2, perpendicular to 45 degrees oblique to the upper left.

The method is very simple, note that b is a sliding support, and the support reaction force must be perpendicular to the support plane. Therefore, for the moment of point a, considering the moment equilibrium condition, the constrained reaction force of point b can be obtained. Considering that the net force in the horizontal and vertical directions is zero, the constrained reaction force at point A can be obtained.

downward, the acceleration is (m+m)gsin m

Force analysis of isolated wood panels.

In order for the plank to rest relative to the inclined plane, there must be a force f along the inclined plane, that is, the friction force of man against the board.

fsinθ+ncosθ=mg

fcosθ=nsinθ

The solution yields f=mgsin

According to Newton's third law, the frictional force of the plate against the person is also f, and the direction is downward along the inclined plane.

Re-isolation of human stress analysis.

It can be directly obtained from Newton's second law.

f+mgsinθ=ma

The solution yields a=(m+m)gsin m

Obviously, the direction is down the slope.

People should move upward.

The magnitude of acceleration is: mgsin m

The inclined plane is smooth, and the wooden block must be stationary, and it must be subject to upward friction, which can only be provided by people, so the friction of people is downward, so people have to run upwards.

p=vi i=p/v=1000/220

Regardless of the change in resistance, if the voltage is one-half of the rated voltage, then the current is also one-half of the rated current, then the actual power becomes one-quarter of the rated power 250W