Q. 153.8( 35 Votes )
In Exercises 3.13 and 3.14, we have carefully distinguished between average speed and magnitude of average velocity. No such distinction is necessary when we consider instantaneous speed and magnitude of velocity. The instantaneous speed is always equal to the magnitude of instantaneous velocity. Why?
Answer :
Instantaneous velocity is defined as first derivative of distance with respect to time, vin = 
m/s
The time interval dt is very small such that direction particle doesn’t change. Since, velocity and speed differ in direction only.
Thus,
Instantaneous velocity = Instantaneous speed ……always
Rate this question :
How useful is this solution?
We strive to provide quality solutions. Please rate us to serve you better.
PREVIOUSA man walks on a straight road from his home to a market 2.5 km away with a speed of 5 km/h. Finding the market closed, he instantly turns and walks back home with a speed of 7.5 km/h. What is the(a) Magnitude of average velocity, and(b) average speed of the man over the interval of time (i) 0 to 30 min, (ii) 0 to 50 min, (iii) 0 to 40 min ?[Note: You will appreciate from this exercise why it is better to define average speed as total path length divided by time, and not as magnitude of average velocity. You would not like to tell the tired man on his return home that his average speed was zero!]NEXTLook at the graphs (a) to (d) (Fig. 3.20) carefully and state, with reasons, which of these cannot possibly represent one-dimensional motion of a particle.
Related Videos
Motion in a Straight Line - 1063 mins
Motion in a Straight Line - 0665 mins
Motion in a Straight Line - 0556 mins
Motion in a Straight Line - 0372 mins
Motion in a Straight Line - 1169 mins
Understand The Interesting Concept Of Relative velocity in 1- Dimension44 mins
Motion in a Straight Line - 0755 mins
Polish Important Concept of Relative Velocity61 mins
Motion in a Straight Line - 0152 mins
Motion in a Straight Line - 0261 mins
Motion in a Straight Line - 1063 minsMotion in a Straight Line - 0665 minsMotion in a Straight Line - 0556 minsMotion in a Straight Line - 0372 minsMotion in a Straight Line - 1169 minsUnderstand The Interesting Concept Of Relative velocity in 1- Dimension44 minsMotion in a Straight Line - 0755 minsPolish Important Concept of Relative Velocity61 minsMotion in a Straight Line - 0152 minsMotion in a Straight Line - 0261 minsTry our Mini CourseMaster Important Topics in 7 DaysLearn from IITians, NITians, Doctors & Academic Experts
view all courses
Dedicated counsellor for each student
24X7 Doubt Resolution
Daily Report Card
Detailed Performance Evaluation
RELATED QUESTIONS :
For the one-dimensional motion, described by x = t–sint
Physics - ExemplarIn one dimensional motion, instantaneous speed v satisfies 0 ≤ v < v0.
Physics - Exemplar