Objects A and B are at the origin. If object A moves to (-6 ,7 ) and object B moves to (-6 ,-1 ) over 3 s, what is the relative velocity of object B from the perspective of object A? Assume that all units are denominated in meters.

3 Answers
Chitram Banerjee
Apr 29, 2016

8/3ms^-1

Explanation:

Relative velocity is a vector quantity. Lets check component wise:

  • x-component:
    Both the bodies have moved to the same vertical line, namely x= -6 line. Hence their x-components of the velocities are same.

  • y-component:
    The distance between their final positions is: (7-(-1)) = 8" m"
    Hence the relative velocity along y-axis is: 8/3 ms^-1

Hence the relative velocity is 8/3 ms^-1 along y-axis.

ali ergin
Apr 29, 2016

v_A=2,67 " m/s"

Explanation:

enter image source here
"displacement=8 meters"

v_A=("displacement")/("time")

v_A=8/3

v_A=2,67 " m/s"

P dilip_k
Apr 29, 2016

In 3s displacement of A from (0.0) to (-6,7) =vecd_A=(-6hati+7hatj)m
Velocity of A , vecV_A=vecd_A/3=1/3(-6hati+7hatj)m/s

In 3s displacement of B from (0.0) to (-6,-1) =vecd_B=(-6hati-hatj)m
Velocity of B, vecV_B=vecd_B/3=1/3(-6hati-hatj)m/s
The relative velocity of object B from the perspective of object A
is vecV_B-vecV_A=1/3(-6hati-hatj+6hati-7hatj)=-8/3hatjm/s
So magnitude of relative velocity is 8/3m/s and it is directed towards negative direction of y-axis i.e. 270^o with positive direction of X-axis

Related questions
See all questions in Relative Motion
Impact of this question
2729 views around the world
You can reuse this answer
Creative Commons License