There are a few options in physics that I don t understand, help me solve them, thank you! 10

1. The 5th second is the time, and the 5th second is the time.

2. The displacement of the object is a directed line segment from the starting point to the end point, and the distance of the object is the trajectory of the object's motion. So it's wrong.

3. In any case, time is time, it is a period, a moment is a moment, it is a point in time.

8:00 and 8:45 here both denote the moment, but if we talk about the length of time from 8:00 to 8:45, it is time.

4. This is only true in linear motion, and at the beginning of your question it is not clear whether it is linear motion or not, so it is wrong. Because velocity and acceleration are both vector quantities that have both magnitude and direction.

1. Five seconds is the time and the end of the fifth second. The fifth second is a period of time, which is equivalent to the end of the fourth second to the end of the fifth.

2. The displacement is a vector (with direction) and the distance is a scalar (without direction), which can never be equal in sense. However, the magnitude of the displacement can be equal to the distance.

3. Error, time is a continuous quantity, and time is an instantaneous quantity, which cannot be equivalent. From how many points to how many points, it is actually a period of time that lasts, so it refers to time. If you say 8:00 alone, then that's the moment.

4. Acceleration is a vector, but it must be ensured that the acceleration is in the same direction as the initial velocity, so as to ensure that when the acceleration is positive, the object will accelerate the motion, otherwise, it is a deceleration motion. For example, in the positive direction of downward, the acceleration of an object thrown upwards is straight downward, and contrary to the initial velocity, the object decelerates until it reaches its highest point. Then, the object accelerates downwards because the acceleration is in the same direction as the velocity.

1,5 seconds refers to the end of 5 seconds, which is the moment; The fifth second refers to the period from the end of the fourth second to the end of the fifth second.

2. The displacement is a vector, with direction and size, and the distance has no direction, only size, which is a scalar quantity. How do you compare displacement to distance? If you just compare the sizes, then when doing a linear motion, the size is the same.

3, this is a problem, the moment refers to a point in time, the time refers to a time period, 8:00 to 8:45, which is to use two moments to represent the time, where 8:

00, 8:45 are all moments, 4, obviously wrong, it should be the acceleration and speed direction is our specification, for example: the object velocity is -100m s, acceleration 5m s 2, then the object will be decelerated, of course the speed will become smaller.

1.The fifth second refers to the time, and the fifth second refers to the moment.

2.The displacement is a vector quantity and has a direction, and the distance is a scalar quantity. It can only be said that the magnitude of the displacement may be equal to the distance.

3.I think so.

4.On the number axis, when the initial velocity is to the left and the acceleration is to the right (positive), the velocity of the object decreases and then increases.

1 Five seconds indicates the moment of the fifth second, and the fifth second is a time period, one is instantaneous, and the other is a time period.

2 False Displacement is the distance between two points and distance is the length of the trajectory taken.

3. One is the time period and the other is the time at that time, alas.

4 The plus or minus of acceleration is the direction you choose!

1.The fifth second refers to the time, and the fifth second refers to the moment.

2.Wrong. 3.Indicates the length of time, which is time.

1. Whether the internal resistance of the motor is the total resistance depends on whether there is other resistance in the resistance, if there is no other resistance in the whole circuit, the inner group of the motor is the total section group of the entire circuit. Because it contains a motor, it is a non-pure resistive circuit, so the U=IR of the entire circuit is not true.

2. The voltage at both ends of the motor U=IR (R is the resistance of the motor), this formula is no longer valid. In other words, this formula cannot be used to calculate the voltage at both ends of the motor. Circuits in which motors are present are non-purely resistive circuits.

As long as you select an electric motor in the object of analysis, U=IR does not hold.

3. For pure resistance other than the motor, U=IR is still valid.

For electric motors, by the law of conservation of energy, the electrical power of the motor = thermal power + mechanical power, that is, UI = i square r + p mechanical power.

The voltage relationship and current relationship of the series-parallel circuits in the circuit still holds.

4. Happy New Year to you, too.

An electric motor is a non-pure resistance machine, and part of the electrical energy consumed is converted into the mechanical energy of the blade rotation, and part of it is converted into thermal energy on the internal resistance. The voltage at both ends of the motor cannot be obtained by multiplying the current by the internal resistance, but it can be obtained by dividing the total power by the current. The heat of impure resistance is mainly the heat energy consumed by converting into internal resistance, which can be calculated by multiplying the square of the current by the inner resistance and the time.

Question 15:

From the formula s=v*t, we can know that v(average)=s(total) t(total), and at a distance of 1 3, the velocity is v1, then t1=(1 3s) v1,, in the same way, t2=(2 3s) v2, and t total = t1+t2=(3*v2+6*v1)s (v1*v2) then v(average) = s t total = (v1 v2) (3 v2 + 6 v1).

Question 16: 1) The acceleration of the 1st to 6th s is:

a1=(v-v0) t=(6-2) 6=2 3 m s 2 The same gives a2=(6-6) 6=0 m s 2a3=(0-6) 4= m s 2

2) Find the displacement of the object within 16s, that is, find the area of the figure enclosed by the figure between t=0 and t=16, which should be s1+s2+s3= (2+6) 6 2 + 6 6 +[4 6 =72 m

Acceleration is equal to the difference in velocity compared to the difference in time.

0 6s: a=(6 2) 6=2 3 meters per second squared 6 12s: a=0

12 16s:a=(0 6) (16 12)= The square displacement of meters per second is equal to the sum of the areas below the upper line of the graph.

The current weakens, the magnetic field of the current weakens, and the magnetic flux passing through a decreases; In order to reduce the obstacle, the area of the A ring will be "reduced" to obstruct the reduction of the net magnetic flux (the concept of "net magnetic flux" is involved here, because B is equivalent to a bar magnet, the right end is the n pole of the magnet, all the magnetic inductance lines inside the magnet pass through A from left to right, and only part of the external magnetic inductance lines pass through A from right to left, and the "net magnetic flux" through A is the difference between the above two) ==>A is true or false.

When b is energized, a magnetic field is generated, and the s n you marked is correct.

At this time, for A, the magnetic field in this direction is decreasing [because the current is decreasing], and the magnetic field that prevents it from decreasing is generated, and the induced current is generated in the direction of [the part outside the paper, downward].

To determine the force of this current in the magnetic field of B, outside B, the direction is Euno n-to-s, and the part of the wire outside the paper is subjected to the force inward. Some of the wires on the paper are also stressed inward, so choose A

It is known from Lenz's law.

The magnetic flux through a is "inside the coil minus the part of the external magnetic flux contained in a" and the total magnetic flux becomes smaller, so a becomes smaller to slow down this change.

The main thing you have to know is that the magnetic flux through a has two directions, one inside and one outside.

Buddy physics learning should be based on books. This kind of question really shouldn't be asked. Mike explained. Read the textbook over and over again. Hopefully, there will be no problems at this level.

First of all, the velocity before 3 seconds is not the maximum, and then assume that the velocity at this time is v, and after 3 seconds of deceleration, the velocity at this time becomes 5m s, and the problem knows that the acceleration = -1m s*2 can be calculated to know the velocity v = 8m s before 3 seconds

From 5m s, it will continue to slow down... I decelerated for another 3 seconds, bringing in VT = V0 + AT= 5 - 3 = 2m s

Hope it helps

From the displacement law of the small slider after the electric field is added, it can be seen that its original velocity direction is in the negative direction along the x-axis.

1) From the given displacement law we get the muzzle velocity v0 m s , and the magnitude of the acceleration is a m s 2

The electric field strength obtained from qe m*a 2*10 ( 6)*e 4*10 ( 2)* is e 2000 Newton coulombs.

2) At the end of the 6th second, the velocity v1 v0 a*t1 m s, the visible velocity direction is along the positive direction of the x-axis, which is determined by s1 t*(v0 v1) 2 6*(, indicating that it is at the origin at the end of the 6th second.

When the positive electric field along the y-axis is added, there is a uniform motion on the x-axis, a uniform acceleration with a muzzle velocity of 0 on the y-axis, and an absolute value of the coordinates x v1 * t2 m (positive coordinates) on the x-axis

On the y-axis, by y a*t2 2 2 2 meters (positive coordinates).

So the location coordinates are (, and the unit is meters.

I watched it for a long time, and I didn't understand it too much, so let's guess.

The equipotential surface when the kinetic energy of the charge is 0 is a zero potential surface, then, according to the law of conservation of energy, the initial kinetic energy + the initial potential energy = the terminal kinetic energy + the terminal potential energy the final kinetic energy = the initial kinetic energy + the initial potential energy - the terminal potential energy = 20j + 0 - 4j

16j

Study well and don't ask others.