If vectors $$\overrightarrow A = \cos \omega t\widehat i + \sin \omega t\widehat j$$ and $$\overrightarrow B = \cos {{\omega t} \over 2}\widehat i + \sin {{\omega t} \over 2}\widehat j$$ are functions of time, then the value of t at which they are orthogonal to each other is
A
$$t = {\pi \over \omega }$$
B
t $$=$$ 0
C
$$t = {\pi \over {4\omega }}$$
D
$$t = {\pi \over {2\omega }}$$
2
AIPMT 2015
MCQ (Single Correct Answer)
+4
-1
The positions vector of a particle $$\overrightarrow R $$ as a function of time is given by $$\overrightarrow R $$ = 4sin(2$$\pi $$t)$$\widehat i$$ + 4cos(2$$\pi $$t)$$\widehat j$$. Where R is in meters, t is in seconds and $$\widehat i$$ and $$\widehat j$$ denote unit vectors along x-and y-directions, respectively. Which one of the following statements is wrong for the motion of particle?
A
Magnitude of the velocity of particle is 8 meter/second.
B
Path of the particle is a circle of radius 4 meter.
C
Acceleration vector is along $$-$$$$\overrightarrow R $$.
D
Magnitude of acceleration vector is $${{{v^2}} \over R}$$ where v is the velocity of particle.
3
AIPMT 2015
MCQ (Single Correct Answer)
+4
-1
Two stones of masses m and 2m are whirled in horizontal circles, the heavier one in a radius $${r \over 2}$$ and the lighter one in radius r. The tangential speed of lighter stone is n times that of the value of heavier stone when they exprience same centripetal forces. The value of n is
A
4
B
1
C
2
D
3
4
AIPMT 2015
MCQ (Single Correct Answer)
+4
-1
A plank with a box on it at one end is gradually raised about the other end. As the angle of inclination with the horizontal reaches 30o, the box starts to slip and slides 4.0 m down the plank in 4.0 s.
The coefficients of static and kinetic friction between the box and the plank will be, respectively
