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Q: How can velocity be zero but not speed even if the object is moving with speed?

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Velocity can change even if speed is constant.

Yes. In order for an object's velocity to be constant, its speed and direction of motion must both be constant. An object moving in a circle, for example, has varying velocity, even if its speed is constant. This situation is known as "uniform circular motion," and the acceleration in this case is called "centripetal [center-seeking] acceleration."

Since the velocity of an object is composed of its speed and its direction, then an object under the influence of Earth's gravity will always be changing velocity. If it is near the surface, its speed is slowing down if it is moving vertically up, or speeding up if it is moving vertically down. If it is moving horizontally, its speed is slowing because of air friction. But even when it is in a circular orbit and its speed is not changing, the direction in which it is moving is constantly changing. so its velocity is constantly changing. Since we have no information on what the flight is, there is no useful answer.

"Velocity" means the speed of the object and the direction in which it's moving.If the direction changes, then the velocity has changed, even though the speedmay be constant.

No. Speed is the magnitude of velocity. If the speed varies, so will the velocity, even if you are moving in a uniform direction.

Yes. Velocity combines the descriptions of speed and direction. If the direction of motion is changing, like moving along a curve or bouncing off a wall, then the velocity is changing, even though the speed may be constant.

Yes. For a start, this happens when the object moves at a constant velocity. Also, if moving in a straight line, even if the object changes speed there must needs be a moment when its instantaneous speed is equal to its average speed - since it cannot change speed suddenly, it must do so gradually.

The velocity can still change, even if the speed doesn't. This is because velocity is a vector - not only the magnitude is important, but also the direction.

Velocity is a vector quantity in which both magnitude and direction must be taken into consideration. For an object to have constant velocity, it is necessary that both the magnitude and the direction of the velocity must be constant. Even if either magnitude or direction is variable, velocity will not remain constant. On the other hand, speed remains constant if direction is changed and magnitude is kept constant, as speed is a scalar quantity.For an object to have constant velocity, it is necessary that the object move at a constant speed and not change course. That object must move in a straight line to have a constant velocity.

Because even though the speed of an object moving in a circular path is constant, its velocity is not. And according to Newton's first law a change of velocity is evidence of a force. The difference is that speed is just the absolute value of velocity, it just says how many units of distance an object can travel in one unit of time. Velocity on the other hand also contains information about the direction of an object (you can regard it as 3 numbers specifying the speed in x, y and z directions). And the direction of motion for a body moving in a circular path DOES change even though its speed does not, therefore a force is needed. (The force decreases the speed in one direction and increases it in another).

No. Velocity is the combination of speed and direction. If it is constant, then both the speed and direction are constant. On the other hand, velocity can vary even is speed is constant, since the direction can change.

No, constant velocity implies constant speed. But velocity can change even when speed remains constant, since speed is a scalar quantity but velocity is a vector quantity.

Yes. The velocity can change if the speed remains constant and the direction changes.

Of course, since velocity is a vector quantity and speed is a scalar quantity, velocity has something speed does not: direction. Thus, an object can travel at the same speed by has a changing direction of movement, and therefore a changing velocity. For instance, a ball on a string moving in a circle at the same speed is constantly changing its velocity, which results in its path of motion.Yes. Velocity is (speed and direction of motion). If direction changes, then velocitychanges, even if speed is constant.Examples:-- Car going around a curve at a constant speed has changing velocity.-- Anything traveling a circular path at a constant speed has changing velocity.

During uniform circular motion, the velocity of any object is continuously increasing even though its speed its continuous. The velocity of an object is dependent on both its speed and direction. The direction of the body is constantly changing but its magnitude ( or speed) is not at all changing.

Velocity means speed. If something's speed is zero, it is standing still. If its speed is non-zero, it is moving, even if only very slightly.

The rotational Speed or angular velocity of an object does not change even if they move away from the axis, however its linear velocity changes.

A ferris wheel turning at a constant speed has no change in speed. But velocity is speed with a direction vector attached to it. Speed with a direction component is velocity. In this case, the distance per unit of time (speed) that something is traveling is constant, but the direction it is traveling is constantly changing because that something is moving in an arc (or circle). It's a ferris wheel, and anything on it has its velocity changing. Velocity is changing every second because the direction it is moving is changing. Any change in the velocity of an object will require that the object be accelerated. Even if its speed is constant, it will experience acceleration to change "just" the direction it is traveling. It's the same with an object in orbit. The object will be cruising along at a constant speed, but its velocity will be constantly changing. This is because the direction the object is moving is changing because it is being accelerated constantly to get it to move in an arc. The object was put in orbit, and it was accelerated into that orbit. Now, the object is being acted on constantly by gravity. The gravity is pulling the object back to earth, but if we look at where it is going at any instant of time, it is moving on a tangent to its path of travel. It moves a tiny bit on that tangent, and gravity pulls it "in" just a tiny bit, and that makes it path an arc. A little on the tangent, and a little "in" toward earth. A little more on the "new" tangent path, and a little "in" toward earth. A little more along the new tangent path, and a little more in toward earth. A smooth arc - a circle. The object in orbit is constantly being accelerated toward earth, and this acceleration constantly changes its velocity (but not its speed), and it moves in that circular orbit.

Velocity is a vector whereas speed only has magnitude, velocity takes into account an objects speed as-well as its direction. When an object has changing velocity, the object is said to be accelerating. The situation you describe is known as circular motion.

Acceleration is the change in velocity. Velocity is the change in speed or direction. Therefore, acceleration is changing the change in speed or direction. So if you are going at 50mph and then you are going at 55mph and then at 60mph, your acceleration is constant at 5 mph. if the change in accleartion is changing, then it is not constant. If you turn dirctions even while you move at a constant velocity, you are accelerating.

This answer assumes that the reader has a fundantal knowledge of what Doppler effect and Doppler radar are. To be effective, Doppler radar, which is an application of the Doppler effect, must be used with the object moving right at or directly away from the Doppler source. It is possible to use Doppler radar on a target moving at a slant, but the angle of convergence or divergence would have to be known and calculations would have to be made to get a correct answer as to that object's velocity. In an situation where it is used to determine radial velocity, it would be tricky to get it to work in this application. Radial velocity is the movement of an object in a circle or an arc of a circle. If the radial velocity of an object was being was investigated, one could use Doppler radar. But there are some issues. Understand that the object is moving in an arc or a circle, like a ball on the end of a string that is being whirled about. The observer would probably want to stand outside the circumference of the circle. Then a "line of sight" would have to be set up to catch the tangent of the circle so the speed of the object could be sampled in an instant when it was moving directly at or away from the Doppler source. This is possible, but challenging. The radius would have to be measured (if it was not know) and a calculation would have to be made. With the radius of the path of travel measured, and the instantaneous speed discovered via the Doppler radar, a calculation would be rather simple. Note that the radial velocity found would be an instantaneous radial velocity. It the radar unit could not be used to sample an instant when the object was moving right at or directly away from the Doppler source, this would make the calculation really, really difficult. It is still mathematically possible to find an object's radial velocity by measuring the speed of an object that is not moving directly at or away from the source, but it's really, really hard. The angle of the objects path of travel with reference to the direction to the Doppler source would have to be known at the instant the radar imaged its speed. Some calculations could then be made. But it's tough. Certainly if the object under investigation is moving laterally with reference to the radar source (moving directly perpendicular to the line of sight from the radar unit), the source will not be able to see it as it is moving at a right angle to the radar. That means no Doppler effect with which the electronics can work to determine speed. Let's wrap up on this important note. When any object moves in anything but a straight line, its velocity is changing - even if its speed remains constant. That's because velocity is speed with a direction vector tacked on to it. An object moving on a radial path is constantly changing velocity, even if it's just changing direction and moving at a constant speed.

If the car is moving at a constant speed but is changing direction, it is accelerating. Acceleration is change in velocity, and velocity includes magnitude (speed) and direction.

Yes. Velocity is both speed and direction. A change in either one is acceleration.

Yes; if the direction changes (for instance, if an object moves in a circle), even if its speed doesn't change, its velocity changes. This is because the term "velocity" also includes the direction.

An object can not accelerate if the speed is constant.