How to find the highest point and the lowest point of physics in a circular motion

First of all, find out where the resultant external force of any object at rest in this motion space is going, this direction is the direction of the lowest point of physics, and the opposite is the highest point of physics. Of course, it can also be judged by the velocity of this circularly moving object, the speed of the highest point of physics is the smallest, the kinetic energy is the smallest, and the potential energy is the largest; The physical nadir has the highest velocity, the highest kinetic energy, and the lowest potential energy. (in the case of not being pushed in the same or opposite direction as the direction of motion during movement).

In a uniform electric field, the electric field force and gravity of the charged body are both constant forces, and the gravity and electric field forces can be combined, then the f combination is equivalent to the new gravity, a = f is equivalent to the new gravitational acceleration, and the direction of the f combination is equivalent to the direction of "vertical downward".

Similar to the case where only the gravitational field acts, the direction of the f-junction is the equivalent lowest point (the physical lowest point), and the opposite is the equivalent highest point (the physical highest point).

When the object is at the lowest point of physics: the velocity is maximum, the kinetic energy is maximum, and the pressure on the ring is also maximum;

When the object is at the highest point of physics: the velocity is minimal, the kinetic energy is minimal, and the pressure on the ring is minimal. The answer is supplemented that there are pictures but you can't add them, and it will be clearer to make the pictures when you do them.

The point where the direction of the resultant force is perpendicular to the direction of velocity is the equivalent highest and lowest point. The combined force between the two points is determined.

Find the resultant force first, the direction of the resultant force is the lowest point of physics, and the opposite direction is the highest point of physics.

If you want to find the law of motion of an object with initial velocity in a composite field of gravity and electric field force This problem generally does not use Newtonian kinematics, which is more complicated and easy to solve from the energy point of view. Hope that helps.

At the highest point, the velocity is the least, and on the contrary, the velocity is the maximum.

The position pointing to the center of the circle is the "highest point", the gravitational force and the electric field force.

The position where the direction of the resultant force is opposite to the center of the circle is the "lowest point". The velocity at the highest point of physics is the smallest, the kinetic energy is the smallest, and the potential energy is the largest. The physical nadir has the highest velocity, the highest kinetic energy, and the lowest potential energy. (in the case of not being pushed in the same or opposite direction as the direction of motion during movement).

Characteristics of circular motionUniform circular motion.

Characteristics: The trajectory is circular, angular velocity.

Period, linear velocity.

(Note: because linear velocity is a vector, the magnitude of linear velocity is constant, and the direction is changing from time to time) and the magnitude of centripetal acceleration are constant, and the direction of centripetal acceleration is always pointing to the center of the circle.

Linear velocity definition: The length of the arc through which a particle moves in a circle.

The ratio of l to the time δt used is called linear velocity, or the product of angular velocity and radius.

Physical Meaning of Linear Velocity: Describes how fast or slow a particle moves in a circular circle and is a vector.

Definition of angular velocity: radian of the radius of rotation (radian system.

360°=2) to the time t elapsed. Definition of period (constant angular velocity in uniform circular motion): the time taken by an object in uniform circular motion to turn around in one cycle.

Definition of rotational speed: the number of revolutions per unit time of an object moving in a uniform circumferential motion.

Set the speed signal intensity at the highest point to v1 and the lowest point speed to v2

Then at the highest point, there is mv1 2 r=fn+mg, and at the lowest point, mv2 2 r=fn-mg

The speed of the line at the highest point cannot be 0, and the speed of the minimum is gr

The speed of the rod at the highest point of the Zhitan game can be 0

The difference between the highest and lowest points of the circular motion is 6 times.

The small arc analysis during the movement process shows that in a very short time, the tension in the visual rod does not do work.

According to the functional principle, the work done by gravity is equal to the amount of change in the mechanical energy of the system formed by the rod and the ball (and the earth).

The level at the lowest point where the rod is taken is zero potential energy surface.

The mass of the ball is m, the lowest point of incidence velocity is v1, the rod length is r, the highest point velocity is v2, the lowest point tension is f1, and the highest point is f2.

The pointing of f2 depends on the incident velocity v1. Considering the critical case of f2=0, there are:

f1-mg=mv1^2/r

1/2mv1^2=1/2mv2^2+2mgrmg=mv2^2/r

The solution is that F1 = 6 mg, and the remaining two cases of F1-F2 = 6 mg are also similar to the above analysis.

In summary: the difference between upper and lower tension is 6mg. Quietly.

First of all, at the highest and lowest points of circular motion, the physical forces experienced by the object differ.

Highest point: At the highest point of circular motion, the velocity of the object is minimal. According to Newton's first law (law of inertia), an object will continue to move in a tangential direction until other forces cause it to change its state of motion.

The forces exerted on an object at its highest point include gravity and centripetal force. Gravity acts downwards and points to the center where the object is located; Whereas, the centripetal force is directed towards the center of the circle, always perpendicular to the velocity vector, and provides the desired centripetal acceleration. The resultant force of these two forces is downward and perpendicular to the velocity vector.

Nadir Point: At the lowest point of circular motion, the velocity of the object is maximum. According to the law of inertia, an object will continue to maintain a state of motion in a straight line with a relatively uniform velocity unless other forces cause it to change its state of motion.

The force exerted on an object at its lowest point also includes gravity and centripetal force. Gravity acts downwards and points towards the center where the object is located; Whereas, the centripetal force is still directed towards the center of the circle and provides the required centripetal acceleration. The resultant force of these two forces is downward and perpendicular to the velocity vector.

Summary: At both the highest and lowest points of circular motion, the resultant force of gravity and the argumentative centripetal force on the object is downward and perpendicular to the velocity vector.

Due to the presence of centripetal force, the object is able to maintain a path of circular motion.

The force analysis of each model of circular motion at the highest point and the lowest point is as follows:

Rope model: When the object is at the highest point, the pulling force of the rope on the object is equal to the gravitational force of the object; At the lowest point of the slag, the pulling force of the object is equal to the gravitational force plus the elastic force.

Rod model: When the object is at the highest point, the force of the rod on the object can be up or down, there are various possibilities; At the lowest point, the force of the rod on the object can be up or down, and there are various possibilities.

Ring model: when the object is at the highest point, the elastic force of the ring on the object must be downward in this direction, and the magnitude is equal to the gravity of the object plus the elastic force of the rod on the object; At the lowest point, the elastic force of the ring on the object must be upward, equal to the gravitational force of the object minus the elastic force of the rod on the object.

In circular motion, there are different force models, and their force analysis will be different depending on the specific situation. The following is a force analysis of the highest and lowest points in several common situations:

1.In the simplified case, the particle destroys the motion in the vertical plane:

Highest point: When the particle reaches its highest point, the vertical downward gravity becomes the only force because the velocity of the particle is zero at the highest point. Due to gravity, the particle will produce a downward acceleration and the direction of the resultant force will be directed towards the center of the circle.

Nadir point: When the mass reaches its lowest point, the combined force of gravity and centripetal force points to the center of the circle. The gravitational force is downward, and the centripetal force is toward the center of the circle. The direction of the selling line of the resultant force determines the direction of acceleration of the mass point at the lowest residual point.

2.Rotation of the rigid rod body in the vertical plane:

Highest Point: When the rod body reaches its highest point, the resultant force of the vertical downward gravity and the centripetal force becomes the only force. Gravity produces a downward moment, and centripetal force produces an upward moment. The direction of the resultant force determines the direction of angular acceleration of the rod at the highest point.

Nadir point: When the rod reaches its lowest point, the resultant force of gravity and centripetal force points to the center of the circle. The gravitational force is downward, and the centripetal force is also directed towards the center of the circle. The direction of the resultant force determines the direction of angular acceleration of the rod at the lowest point.

It is important to note that the above force analysis is performed without regard to air resistance and other non-conservative forces such as friction, and only if the circular motion is smooth enough. If other additional forces or resistance are present, the force analysis is more complex and requires a more detailed analysis on a case-by-case basis.

The problem of the highest point and the lowest point that you are talking about must be in the vertical plane, because the mechanical energy is conserved, and it cannot be a uniform velocity, just an ordinary circular motion.

The rope pulls the ball in a circular motion, and the lowest point receives the tensile force t1, the gravity mg, and the combined external force provides the centripetal force. At this time, the speed is v1

With t1-mg=mv1 l, the size of t1 can be obtained. (The general question is to find the size of t1, and you may also ask if you will break the rope, which is also to find the size of t1.) ）

The rope is at its highest point, and the circular motion can only be maintained when the speed reaches a certain value. Let the speed v2 at this time. If V2 is too small, the gravitational force is greater than the centripetal force that moves in a uniform circular motion at that speed, and the rope will relax the object and throw it diagonally before reaching the highest point.

In critical conditions, gravity provides exactly the centripetal force, and the rope has no pulling force.

mg=mv2 l v2= (lg), so the velocity at the highest point is at least (lg) (the problem needs to find this velocity first and then find something else.) ）

The movement of the pole pulling ball is similar to that of a rope, it is the same at the lowest point, and the rod will not slack when the highest point is different, and it will reach 0 speed at the highest point. The force of the rod on the ball may be straight upwards or straight downwards.

Generally we assume that the two combined external forces of upwards and gravity provide centripetal force.

There is mg-f=mv l, f=mg-mv l

When the value of f is positive, the direction is vertically upward; If it is negative, it means that the direction is straight down.

Hope it helps you o ( o haha

At the highest point, the gravity of the ball is downward, if mv 2 r=mg, it means that there is no pull on the rope, mv 2 r>mg, the pull force of the rope f=mv 2 r-mgmv 2 r at the lowest point, the gravity is down, the pull is up, and the pull force is definitely greater than the gravitational force. f=mv^2/r+mg。

Past the highest point mg+t=ma

Past the lowest point t-mg=ma

t points to the center of the circle is positive, the highest point of the rod is t can be negative, the highest point t of the rope must be positive or 0, and the lowest point t must be positive.

The lowest point rope and the rod are subjected to the same force, gravity pull, and the resultant force provides centripetal force.

The highest point is 1When gravity just provides the centripetal force, neither the rod nor the rope is subjected to force.

2.When the velocity is greater than the critical (v = root number gr), it is the gravitational and tensile forces that provide the centripetal force.

3.When the speed is less than the critical point, the rod has support, that is, the gravity and the supporting force provide the centripetal force (gravity is greater than the support force), and the rope does centripetal motion without support, which is not a complete circumference.

Mainly analyze the force and imagine the situation.

Analyze clearly, the gravity of the object, the rope has no support force, while the wooden pole has a support force, so the situation needs to be considered.

Suppose there is a smooth circular orbit of radius r in a vertical plane, and the object rushes up from the bottom with a certain initial velocity v, "just past the highest point".

"Exactly" means that gravity does the centripetal force.

Because the supporting force of the track happens to be zero), at this time the speed of the potato bench can be obtained as v 0 = gr).

It won't fall", let's look at this moment with a velocity of v 0: when there is no circular orbit limit, it will do a flat throwing motion.

As for whether the object will be confined to the circular orbit when there is a circular orbit, you can compare the trajectory of the above-mentioned flat throwing motion with the position of the circular orbit, if the trajectory of the flat throw will exceed the circular orbit, or the trajectory of the flat throw will appear on the outside of the circular orbit, then the object will be limited to the circular orbit after that.

And so it is, a royal parabola.

A circle of curvature at a vertex.

It's the hand source wrapped around the inside of the parabola (I haven't proven it, the geometry is intuitively so, and it takes a bit of tongue to prove it). At the same time, when calculating v 0, it is already "gravity as centripetal force", then in turn we can know the radius of curvature of this flat throwing motion at v 0.

is r, then we know that the motion of the object will be limited by the circular orbit.

As for the subsequent motion, will the object fall off the circular orbit?

It can be assumed that it falls off after moving an angle in orbit, which should obviously be an acute angle. If it falls off, then the radial component of gravity should be greater than the circular motion.

The magnitude of the centripetal force required. But in fact, the result is the opposite, and it is calculated that the centripetal force required for the radial component of gravity is mgcos( ) is mg(3-2cos( ) The former is less than the latter, the circular orbit still supports the supporting force, and the object does not fall off.

This should be in the conservative force.

The position of the question. That is, gravity, the electric field force.

Wait. The highest point, the direction from the center of the circle to the point, and the point opposite to the direction of the conservative force, for example, just by gravity, the balance is the highest point.

The lowest point, the direction from the center of the circle to the point, is the same as the point where the conservative force is occlused, such as only by gravity, which is the lowest point.

At the highest point, if it is a soft segment, then gravity and the pull of the rope do not act as a centripetal force.

At a minimum, the pull force is 0. The lowest point of tension and gravity acts as a centripetal force.

In the case of a stick, it is even possible to pass through the highest point at a speed of 0, and the centripetal force is gravity minus support, or gravity plus pull. The lowest point is the same as above.