Physics

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

012 ###### 2013-01-04 13:37:31

Speed is distance by time and velocity is displacement by time. If an object is moving with speed distance can never be zero but displacement can. So we say velocity can be zero.

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## Related Questions "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.  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. 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. 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. No. Speed is the magnitude of velocity. If the speed varies, so will the velocity, even if you are moving in a uniform direction. 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. 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. 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. 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. 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. Yes. The velocity can change if the speed remains constant and the direction changes. 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." 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. 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. 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). 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. 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.  No. Velocity combines speed and the direction of motion.Constant velocity is constant speed in a straight line.In circular motion, the velocity is always changing even if the speed is constant,because the direction is always changing. A change in the direction of motion IS a change of velocity,even if the speed doesn't change. Yes. Velocity is both speed and direction. A change in either one is acceleration. 0 velocity 0 acceleration The forces on the object are balanced: it is in equilibrium. (The forces are balanced on any object with 0 acceleration, even if it is moving.) 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. 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.

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