Question
A particle moves so that its position vector is given by r = cos 
where 
is a cosntant. which of the following is true?
-
velocity and acceleration both are parallel to r
-
velocity is perpendicular to r and acceleration is directed towards the origin
-
velocity is perpendicular to r and acceleration is directed away from the origin
-
velocity and acceleration both are perpendicular to r
Solution
B.
velocity is perpendicular to r and acceleration is directed towards the origin
Position vector of the article is given by,
where 
is a constant.
Velocity of the particle is,
The particle is at a point P. That is, its position vector is directed as shown below:
Therefore, acceleration is directed towards -r, that is towards "O"We have
