Motion in 1-D Fundamentals - Speed
Description:
The Concept
Rate of change of distance w.r.t. to time is called Speed.
Average Speed = Total distance coveredTotal time taken = ΔxΔt
Where,
‘Δx’ is the distance/path length
‘Δt’ is the time taken
Instantaneous Speed = limΔ t→0 ΔxΔt = dxdt
Speed is a scalar quantity. (Both Distance and Time are Scalars)
Speed is always positive. (Distance and Time are never negative)
Example Problem
A car drives from Mumbai to Pune, 150 km. It makes several stops in the middle and reaches the destination in 3 hours. Comment on the Average and Instantaneous speed of the car.
Solution
For average speed, one can calculate the ratio of total distance and total time.
Average Speed = ΔxΔt = 150 km3h = 50 km/h
As the person moves with variable speed and stops frequently, it is impossible to determine instantaneous speed simply by the information provided. Therefore,
Instantaneous Speed = dxdt = Inderminate