1
WB JEE 2017
MCQ (Single Correct Answer)
+1
-0.25
Change Language
Two particles A and B (both initially at rest) start moving towards each other under a mutual force of attraction. At the instant, when the speed of A is v and the speed of B is 2v, the speed of the centre of mass is
A
zero
B
v
C
$${{3v} \over 2}$$
D
$$-$$ $${{3v} \over 2}$$
2
WB JEE 2017
MCQ (Single Correct Answer)
+1
-0.25
Change Language
Three vectors $$\overrightarrow A $$ = a$$\widehat i$$ + $$\widehat j$$ + $$\widehat k$$; $$\overrightarrow B $$ = $$\widehat i$$ + b$$\widehat j$$ + $$\widehat k$$ and $$\overrightarrow C $$ = $$\widehat i$$ + $$\widehat j$$ + c$$\widehat k$$ are mutually perpendicular ($$\widehat i$$, $$\widehat j$$ and k are unit vectors along X, Y and Z-axes respectively). The respective values of a, b and c are
A
0, 0, 0
B
$$ - {1 \over 2}$$, $$ - {1 \over 2}$$, $$ - {1 \over 2}$$
C
1, $$-$$1, 1
D
$${1 \over 2}$$, $${1 \over 2}$$, $${1 \over 2}$$
3
WB JEE 2017
MCQ (Single Correct Answer)
+1
-0.25
Change Language
A block of mass 1 kg starts from rest at x = 0 and moves along the X-axis under the action of a force F = kt, where t is time and k = 1 Ns$$-$$1. The distance the block will travel in 6 seconds is
A
36 m
B
72 m
C
108 m
D
18 m
4
WB JEE 2017
MCQ (Single Correct Answer)
+2
-0.5
Change Language
A particle with charge Q coulomb, tied at the end of an inextensible string of length R metre, revolves in a vertical plane. At the centre of the circular trajectory, there is a fixed charge of magnitude Q coulomb. The mass of the moving charge M is such that $$Mg = {{{Q^2}} \over {4\pi {\varepsilon _0}{R^2}}}$$. If at the highest position of the particle, the tension of the string just vanishes, the horizontal velocity at the lowest point has to be
A
0
B
$$2\sqrt {gR} $$
C
$$\sqrt {2gR} $$
D
$$\sqrt {5gR} $$
EXAM MAP
Medical
NEET
Graduate Aptitude Test in Engineering
GATE CSEGATE ECEGATE EEGATE MEGATE CEGATE PIGATE IN
CBSE
Class 12