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
A
0.5 and 0.6
B
0.4 and 0.3
C
0.6 and 0.6
D
0.6 and 0.5
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
A ball is thrown vertically downwards from a height of 20 m with an initial velocity v0. It collides with the ground, losses 50 percent of its energy in collision and rebounds to the same height. The initial velocity v0 is
(Take g = 10 m s$$-$$2)
A
28 m s$$-$$1
B
10 m s$$-$$1
C
14 m s$$-$$1
D
20 m s$$-$$1
4
AIPMT 2015
MCQ (Single Correct Answer)
+4
-1
A remote-sensing satellite of earth revolves in a circular orbit at a height of 0.25 $$ \times $$ 106 m above the surface of earth. If earth's radius is 6.38 $$ \times $$ 106 m and g = 9.8 ms$$-$$2, then the orbital speed of the satellite is
