Fig. shows the distance-time graph of three objects A, B and C. Study the graph and answer the following questions:(a) Which of the three is travelling the fastest?(b) Are all three ever at the same point on the road?(c) How far has C travelled when B passes A?(d) How far has B travelled by the time it passes C?
Thus, B is travelling the fastest. Ans.
(ii) No, all three do not meet at any point on the road. Ans.
(iii) When B passes A at point N (at 1.2 hours), C is at a distance of 8 km from the origin O. Ans.
(iv) B passes C at 0.7 hours. During this time B covers distance = 6 km. Ans.
In our surroundings there are several living and non-living things present whether we are humans, animals, birds, fishes, trains, cars, etc. All these objects, some do motion (move) while some stay at rest. A body is said to be in motion when it continuously changes its position with respect to time and stationary object taken as a reference point and an object said to be in rest if it does not change its position with respect to time and stationary object taken as reference point. For example, you are driving a car with a constant speed, the position of the car also changes constantly with respect to time and your stationary object like house, office or school etc. it means the car is in motion. Motion can be of two types: uniform motion and non-uniform motion let discuss one by one in brief.
(Source: using MS word shapes)
Uniform motion definition: An object is said to have uniform motion when object cover equal distance in equal interval of time within exact fixed direction.
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Example of uniform motion: If an object in uniform motion covers 1m in 1 minute in a given direction, it indicates that it covers 2m in every 2min, 3m in every 3min, 4m in every 4min… and so on.
(Source: using MS word graph)
Some Important features of Uniform motion:
- For uniform motion along a straight path in same direction magnitude of displacement is equal to actual distance covered by body.
2. No force is required in order to maintain the motion.
- When a body is having uniform motion along a straight line in a given direction then, the magnitude of the displacement of the body is equal to the actual distance travelled by body in given time.
- In a uniform motion along a straight line the slope obtained from the position-time graph gives the velocity of the body.
What is non uniform motion?
Non-Uniform motion definition: When the velocity changes of a body by time then it is called by non-uniform motion. Example of non uniform motion: Suppose a vehicle starts moving from rest, its velocity increases for some time, then the velocity may become constant for some time along with finally slow down as well as come to rest again the velocity of vehicle is different at the different instants along with so it has non uniform motion.
(Source: using MS word graph)
Also Read:
Difference between uniform and nonuniform motion
Uniform motion | Non-uniform motion |
An object covers equal distance which is equal interval of the time then object is said to have uniform motion. | An object covers the unequal distance which is equal intervals of time then the object is said to have non uniform motion. |
In uniform motion the object have steady speed or velocity. | In non uniform motion the object have variable speed or velocity. |
Graph plotting between distance and time is always a straight line. | Graph plotting between distance and time is a not a straight line. |
In uniform motion acceleration is Zero. | In non uniform motion acceleration is non-zero. |
Terms related to Uniform and Non Uniform motion
Define uniform speed?
Uniform speed: An object is having the motion with uniform speed, and if it covers equal distance which is in equal distance in the equal interval of time. For example if the car is still in the motion on straight road from home to office, where the distance between office as well as home is 80km in 4 hour and covers 20km in every one hour10km in every half an hour 5km and so on, then we can say that car is with a uniform speed of 20km/h.
Define uniform velocity?
Uniform velocity: A body having motion with uniform velocity if the body over equal displacement in equal intervals of time however small-time intervals may be.
Define uniform acceleration?
Uniform acceleration: The acceleration of the object is uniformly accelerated when the velocity changes by the equal amount in that particular interval of time however small-time intervals may be.
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NCERT Physics Notes:
Last updated at May 12, 2020 by Teachoo
Suppose there are 2 cars
Car 1 and Car 2
Both Car cover a distance of 80 km
Car 1 Covers 40 km in first hour and 40 Km in second hour
Car 2 Covers 30 km in First Hour and 50 Km In Second Hour
It is said that
Car 1 is in Uniform Motion
Car 2 is in Non Uniform Motion
What is Uniform Motion?
A body is in uniform motion if it covers equal distance in equal intervals of time
Example
Car 1 travelling at 40 km in both first and second hour
What is Non Uniform Motion?
A body is in non uniform motion if it covers unequal distance in equal intervals of time
Example
Car 1 travelling at 30 km in first hour and 50 km in second hour
Note
Non Uniform Motion is also called Accelerated Motion
Note
Graph of Uniform Motion is Straight LineGraph of Non - Uniform Motion is Curved Line
In Uniform Motion, Equal Distance is Traveled even over Small Distances
Note
If a body travels at a uniform speed,it means it travels equal distance at equal intervals of time.
It does not matter how small these intervals of time are.
Example
Suppose a train travels 120 kilometer in 1 Hour in uniform motion
It means ,it travels at a uniform speed
In 60 Minutes = 120 Km
In 1 Minutes = 120/60 = 2 Km
In 60 Seconds = 2000 m
I 1 Second = 2000/60 = 33.33 meter
Difference between uniform and non-uniform motion
Uniform Motion | Non Uniform Motion |
It has zero acceleration. |
It has non-zero acceleration. |
Distance-time graph shows a straight line |
Distance-time graph shows a curved line |
Covers equal distances in equal time interval. |
Covers unequal distances in equal time interval. |
Its average speed is same as speed of the object |
Its average speed is different as speed of the object |
Questions
Q 4 Page 102 - What does the path of an object look like when it is in uniform motion?
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