1
JEE Main 2020 (Online) 7th January Evening Slot
+4
-1
An elevator in a building can carry a maximum of 10 persons, with the average mass of each person being 68 kg, The mass of the elevator itself is 920 kg and it moves with a constant speed of 3 m/s. The frictional force opposing the motion is 6000 N. If the elevator is moving up with its full capacity, the power delivered by the motor to the elevator (g = 10 m/s2) must be at least :
A
48000 W
B
62360 W
C
56300 W
D
66000 W
2
JEE Main 2020 (Online) 7th January Morning Slot
+4
-1
A 60 HP electric motor lifts an elevator having a maximum total load capacity of 2000 kg. If the frictional force on the elevator is 4000 N, the speed of the elevator at full load is close to :
(1 HP = 746 W, g = 10 ms-2)
A
1.5 ms-1
B
1.7 ms-1
C
2.0 ms-1
D
1.9 ms-1
3
JEE Main 2019 (Online) 9th April Morning Slot
+4
-1
A uniform cable of mass 'M' and length 'L' is placed on a horizontal surface such that its (1/n)th part is hanging below the edge of the surface. To lift the hanging part of the cable upto the surface, the work done should be :
A
$${{2MgL} \over {{n^2}}}$$
B
nMgL
C
$${{MgL} \over {2{n^2}}}$$
D
$${{MgL} \over {{n^2}}}$$
4
JEE Main 2019 (Online) 8th April Morning Slot
+4
-1
A particle moves in one dimension from rest under the influence of a force that varies with the distance travelled by the particle as shown in the figure. The kinetic energy of the particle after it has travelled 3m is :
A
6.5 J
B
2.5 J
C
5 J
D
4 J
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