1
JEE Main 2018 (Online) 15th April Morning Slot
+4
-1
A given object takes n times more time to slide down a $${45^ \circ }$$ rough inclined plane as it takes to slide down a perfectly smooth $${45^ \circ }$$ incline. The coefficient of kinetic friction between the object and the incline is :
A
$${1 \over {2 - {n^2}}}$$
B
$$1 - {1 \over {{n^2}}}$$
C
$$\sqrt {1 - {1 \over {{n^2}}}}$$
D
$$\sqrt {{1 \over {1 - {n^2}}}}$$
2
JEE Main 2016 (Online) 10th April Morning Slot
+4
-1
A particle of mass m is acted upon by a force F given by the empirical law F =$${R \over {{t^2}}}\,v\left( t \right).$$ If this law is to be tested experimentally by observing the motion starting from rest, the best way is to plot :
A
$$\upsilon$$(t) against t2
B
log $$\upsilon$$(t) against $${1 \over {{t^2}}}$$
C
log $$\upsilon$$(t) against t
D
log $$\upsilon$$(t) against $${1 \over {{t}}}$$
3
JEE Main 2016 (Online) 9th April Morning Slot
+4
-1
A rocket is fired vertically from the earth with an acceleration of 2g, where g is the gravitational acceleration. On an inclined plane inside the rocket, making an angle $$\theta$$ with the horizontal, a point object of mass m is kept. The minimum coefficient of friction $$\mu$$min between the mass and the inclined surface such that the mass does not move is :
A
tan$$\theta$$
B
2tan$$\theta$$
C
3tan$$\theta$$
D
tan2$$\theta$$
4
JEE Main 2015 (Offline)
+4
-1

Given in the figure are two blocks $$A$$ and $$B$$ of weight 20 N and 100 N, respectively. These are being pressed against a wall by a force $$F$$ as shown. If the coefficient of friction between the blocks is 0.1 and between block $$B$$ and the wall is 0.15, the frictional force applied by the wall on block $$B$$ is :
A
$$120$$ $$N$$
B
$$150$$ $$N$$
C
$$100$$ $$N$$
D
$$80$$ $$N$$
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