Question

The displacement of particle moving along x-axis versus time is given in the figure below
The average velocity , $V_{av}$ of the particle in the first four seconds and the velocity V of it at t=4 s are

• A. $V_{av}=-1m/s,V=-1m/s$
• B. $V_{av}=1m/s,V=1m/s$
• C. $V_{av}=1m/s,V=0m/s$
• D. $V_{av}=-1m/s,V=0m/s$

Answer 1

Answer: (D)

$V_{av}=-1m/s,V=0m/s$

At $t=0$, the particle is at a position $5m,$ and at $t=4s$ the particle is at position $1m$.
Thus displacement of particle $S=1-5=-4m$
Time taken $t=4s$
Average velocity $V_{avg}=\frac{S}{t}=\frac{-4}{4}=-1m/s$
Slope of displacement-time graph gives the velocity of particle at that instant.
Slope of the graph is zero at $t=4s$, thus velocity is zero at $t=4s$.