1
JEE Main 2020 (Online) 5th September Morning Slot
+4
-1
A helicopter rises from rest on the ground vertically upwards with a constant acceleration g. A food packet is dropped from the helicopter when it is at a height h. The time taken by the packet to reach the ground is close to :
[g is the acceleration due to gravity]
A
t = 3.4$$\sqrt {\left( {{h \over g}} \right)}$$
B
t = 1.8$$\sqrt {\left( {{h \over g}} \right)}$$
C
t = $$\sqrt {{{2h} \over {3g}}}$$
D
t = $${2 \over 3}\sqrt {\left( {{h \over g}} \right)}$$
2
JEE Main 2020 (Online) 5th September Morning Slot
+4
-1
A balloon is moving up in air vertically above a point A on the ground. When it is at a height h1, a girl standing at a distanced (point B) from A (see figure) sees it at an angle 45o with respect to the vertical. When the balloon climbs up a further height h2, it is seen at an angle 60o with respect to the vertical if the girl moves further by a distance 2.464 d(point C). Then the height h2 is (given tan 30o = 0.5774)
A
0.464d
B
d
C
0.732d
D
1.464d
3
JEE Main 2020 (Online) 4th September Morning Slot
+4
-1
A Tennis ball is released from a height h and after freely falling on a wooden floor it rebounds and reaches height $${h \over 2}$$. The velocity versus height of the ball during its motion may be represented graphically by :
(graph are drawn schematically and on not to scale)
A
B
C
D
4
JEE Main 2020 (Online) 4th September Morning Slot
+4
-1
Starting from the origin at time t = 0, with initial velocity 5$$\widehat j$$ ms-1 , a particle moves in the x-y plane with a constant acceleration of $$\left( {10\widehat i + 4\widehat j} \right)$$ ms-2. At time t, its coordinates are (20 m, y0 m). The values of t and y0 are, respectively:
A
5s and 25 m
B
2s and 18 m
C
2s and 24 m
D
4s and 52 m
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