Physics
Answer
The difference between distance and displacement is as follows:
| Distance | Displacement |
|---|---|
| It is the length of the path traversed by the object in a certain time. | It is the distance travelled by the object in a specified direction in a certain time (i.e. it is the shortest distance between the final and the initial positions). |
| It is a scalar quantity i.e., it has only the magnitude. | It is a vector quantity i.e., it has both magnitude and direction. |
| It depends on the path followed by the object. | It does not depend on the path followed by the object. |
| It is always positive. | It can be positive or negative depending on its direction. |
| It can be more than or equal to the magnitude of displacement. | Its magnitude can be less than or equal to the distance, but can never be greater than the distance. |
| It may not be zero even if displacement is zero, but it can not be zero if displacement is not zero. | It is zero if distance is zero, but it can be zero if distance is not zero. |
Related Questions
Assertion (A) : The velocity-time graph of a body in motion can be a straight line parallel to the time axis.
Reason (R) : This is because the motion of body is with non-uniform velocity.
- Both A and R are true and R is the correct explanation of A
- Both A and R are true and R is not the correct explanation of A
- Assertion is false but reason is true
- Assertion is true but reason is false
Assertion (A) : The acceleration-time graph of а body is a straight line parallel to time axis.
Reason (R) : This depicts the motion of freely falling body under gravity.
- both A and R are true and R is the correct explanation of A
- both A and R are true and R is not the correct explanation of A
- assertion is false but reason is true
- assertion is true but reason is false
Assertion (A) : Acceleration of a moving body is always positive.
Reason (R) : Acceleration is the rate of change of velocity with time.
- both A and R are true and R is the correct explanation of A
- both A and R are true and R is not the correct explanation of A
- assertion is false but reason is true
- assertion is true but reason is false
A lift starts from rest at the ground floor and moves vertically upward along a straight shaft. During the first 4 s, the lift moves with uniform acceleration and attains a velocity of 2 m s-1. It then moves with uniform velocity for the next 6 s. Finally, it is brought to rest uniformly in 2 s at the top floor.
Assuming the motion to be one-dimensional, answer the following:
(a) Calculate the acceleration of the lift during the first 4 s.
(b) Calculate the total height between the ground floor and the top floor.
(c) Draw the velocity-time graph for the complete motion and mark the regions of acceleration, retardation and zero acceleration.
(d) Use the graph to calculate the average velocity of the lift during the upward journey.
(e) If the lift now moves downward following the same pattern, how would the signs of acceleration and displacement change?
(f) "The lift has maximum acceleration when it starts moving." Is this statement correct? Give reason.