Question

whats the angle b/w instantaneous displacement and acceleration during the related motion?

Answer 1

okay i am a bit confused, that since we are talking about relative motion, is the acceleration and displacement relative as well?

never mind.

see. since the angle is being asked, you can well guess that this is something to do with vectors.
now just get the displacement's equation in vector form (if it snot given in that form, you can always assume a coordinate system and then take appropriate directions) at the required instant. now again, find the acceleration's equation for the instant.

now you have to vectors. can you remember how to find the angle between two vectors?
*HINT* dot product!!!

so if acc= (vector a) and displacment= (vector s)
then,

(vector a).(vector s) = |vector a|*|vector b|*cos(theta)

where theta is the angle between the two vectors.

remember how you can find the magnitude term of any vector in i^ and j^ form?

(don't panic if the acceleration and velocity terms aren't in the absolute constant terms, and rather in terms of 'time' or 'displacement, just do the maths there, and do not worry if you didnt understand a bit of what i explained)

again, posting a real problem would really help to illustrate. :)

Answer 2

lol, i meant *two vectors and sorry for the other million typos!

Answer 3

and in the second part of the equation of dot product, i meant

|vector a| * |vector "s"|

and not "b" instead of "s"

Answer 4

actually this is the exact question
and choices are
A.0 B.pi/4
C.pi/2 D.pi

Answer 5

just a second. did you mean "rotated" or "circular" motion above?
or does 'related' itself mean circular??? i feel like an alien again -\(o.O)/-

Answer 6

"related" thats what given in the book
answer is Pi

thers a hint: retardation is directly opposite to direction of motion

Answer 7

then has to be 'pi'.