1
AIPMT 2015
MCQ (Single Correct Answer)
+4
-1
Change Language
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.
2
AIPMT 2015
MCQ (Single Correct Answer)
+4
-1
Change Language
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
3
AIPMT 2015
MCQ (Single Correct Answer)
+4
-1
Change Language
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
A
9.13 km s$$-$$1
B
6.67 km s$$-$$1
C
7.76 km s$$-$$1
D
8.56 km s$$-$$1
4
AIPMT 2015
MCQ (Single Correct Answer)
+4
-1
Change Language
A force $$\overrightarrow F = \alpha \widehat i + 3\widehat j + 6\widehat k$$ is acting at a point $$\overrightarrow r = 2\widehat i - 6\widehat j - 12\widehat k$$. The value of $$\alpha $$ for which angular momentum about origin is conserved is
A
zero
B
1
C
$$-$$ 1
D
2