CBSE-XI-Physics
03: Rest and Motion: Kinematics
- #4A person travelling on a straight line moves with a uniform velocity v1 for some time and with uniform velocity v2 for the next equal time. The average velocity v is given by
-(a)
v=v1+v22
(b)
v=v1v2
(c)
2v=1v1+1v2
(d)
1v=1v1+1v2digAnsr: aAns : (a) `` v=\frac{{v}_{1}+{v}_{2}}{2}``
Velocity is uniform in both cases; that is, acceleration is zero.
We have:
`` {d}_{1}={v}_{1}t`` and `` {d}_{2}={v}_{2}t``
Total displacement, `` d={d}_{1}+{d}_{2}``
Total time, `` t=t+t=2t``
`` \therefore `` Average velocity, `` v=\frac{{d}_{1}+{d}_{2}}{2t}=\frac{{v}_{1}+{v}_{2}}{2}``