We are going to discuss what zero velocity is, and how to plot a zero velocity graph and different facts about the same.
An object is said to have zero velocity when the displacement of an object does not change with time and is at rest.
Zero Average Velocity Graph
The sum of all the velocities of the object divided by the total number of velocities is called the average velocity.
If the object is at a rest or occupies same position after certain time interval then the object is said to have a zero average velocity.
The positions of the object at different time intervals were noted and when a displacement v/s time graph was plotted for the same, we get a straight line with very few points above or below the lines. Those few points not being on a straight line indicates that there was some minute motion of the object which was negligible.
The above displacement v/s time graph indicates that the object is at rest, but due to some external influences, there is some slight motion seen by an object. On average, the position of the object is fixed. This proves that the velocity of the object is nil.
Position Time Graph for Zero Relative Velocity
The relative velocity depends upon the direction of the motion of two or more objects and is the difference between the velocities of the objects.
If the two objects are moving in the same direction with velocity VA and VB respectively, then their relative velocity is V= VA – VB; and if these two objects are moving in the opposite direction to each other, then their relative velocity will become V= VA – (-VB)= VA + VB.
If the object is at rest then the velocity of the will be equal to zero. The above graph is a position-time graph for two objects at rest. If both the objects are not moving and are stable at rest then it is evident that their relative velocity in concurrent to each other is zero.
Two objects elapsing equal distance in equal intervals of time, then the velocity of both the objects will be equal, and hence relative velocity which is the vector difference of the velocities of both the objects will be zero. Because, from the frame of reference of one object, the position of the other object which is moving along with itself will be constant, hence, the relative displacement will be zero and hence the relative velocity will be zero.
Problem: Consider a lady walking along with her dog on the street with a velocity of 1m/s each crosses a tree. Then what will be the relative velocity of a lady with respect to her dog and that of a tree?
Given: Velocity of a lady VA=1m/s
The velocity of a dog VB=1m/s
A tree is at rest and hence the velocity of a tree is VC=0
The direction of motion of both, a lady and a dog is in the same direction.
V= VA-VB=1m/s – 1m/s=0
As a lady crosses a tree, the tree is moving away from a lady at a speed of 1m/s. Since the tree is at rest, in reality, the relative velocity of a lady with respect to a tree is
V= VB-VC=1m/s – 0=1m/s
Hence, the relative velocity of a tree and of a lady with respect to each other is 1m/s.
When is Velocity Zero on a Position Time Graph?
The velocity of the object is zero if the position of the object does not change with time.
If the position of the object marked on the position-time graph is the same forming a straight line on a graph between a time interval, then the velocity of the object during that time interval is zero.
The above is the position-time graph for a zero velocity, the straight line on the graph says that the position of the object is constant at all times and there is no displacement.
Suppose at time t1=5 min the position of the object was found to be x1=300m and at time t1=10 min the position of the object was again found to be x1=300m only, then the velocity of the object
Since there is no displacement, the velocity of the object is found to be zero.
Read more on Zero-Velocity Surface.
Negative Velocity and Zero Acceleration
If the object is accelerating in the direction opposite from its route or the speed decreases with time then the object is said to have a negative velocity.
If the velocity of the object remains constant and is moving in the reverse direction of motion then the velocity is negative and the acceleration of the object is zero.
The above is the graph of negative velocity and time. Since the object after decelerating moves with a constant velocity then the acceleration of the object becomes zero until there is a change in its velocity.
As the negative velocity of the object remains unchanged, the graph of the negative velocity v/s time shows a straight line.
Zero Velocity Graph
The object is said to have zero velocity when there is no displacement of the object. The object at rest remains stable unless and until some external forces are exerted on the body that forces the object to displace from its original position.
Below is a graph for position and time.
It shows that the position of the time remains unchanged for a long duration of time. Since the change of position of the object at different intervals of time is zero; the velocity of the object is zero.
Read more on Negative Velocity Graph: Different Graphs And Their Explanations.
Frequently Asked Questions
Is the object stable if it is not accelerating?
The object is said to be accelerating if its velocity varies with time.
If there is no acceleration means either the object is stable or is moving with constant velocity. If the object is moving then the object is said to have uniform acceleration which does not change with time.
How negative velocity is different from zero velocity?
The objects with zero velocity are fixed at a point whereas those with negative velocity are in reverse motion.
An object with negative velocity is decelerating and hence is in a motion, whereas the object with zero velocity implies that the object is not in motion and is at rest.
An object in a motion can have zero acceleration?
The velocity of the accelerating object is not constant with time.
If the object is moving with a constant velocity with time then the difference between the initial and the final position of the object will be zero and hence the object will have zero acceleration.
What is the effect of zero velocity?
An object with zero velocity will have zero acceleration.
An object will stand fixed at a rest at one position and will not show any displacement unless exerts some external forces.
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Hi, I’m Akshita Mapari. I have done M.Sc. in Physics. I have worked on projects like Numerical modeling of winds and waves during cyclone, Physics of toys and mechanized thrill machines in amusement park based on Classical Mechanics. I have pursued a course on Arduino and have accomplished some mini projects on Arduino UNO. I always like to explore new zones in the field of science. I personally believe that learning is more enthusiastic when learnt with creativity. Apart from this, I like to read, travel, strumming on guitar, identifying rocks and strata, photography and playing chess.