1
JEE Main 2020 (Online) 7th January Evening Slot
+4
-1
A mass of 10 kg is suspended by a rope of length 4 m, from the ceiling. A force F is applied horizontally at the mid point of the rope such that the top half of the rope makes an angle of 45o with the vertical. Then F equal : (Take g = 10 ms–2 and the rope to be massless)
A
100 N
B
75 N
C
90 N
D
70 N
2
JEE Main 2019 (Online) 12th April Evening Slot
+4
-1
A block of mass 5 kg is (i) pushed in case (A) and (ii) pulled in case (B), by a force F = 20 N, making an angle of 30o with the horizontal, as shown in the figures. The coefficient of friction between the block and floor is $$\mu$$ = 0.2. The difference between the accelerations of the blocks, in case (B) and case (A) will be : (g = 10 ms–2)
A
3.2 ms–2
B
0.8 ms–2
C
0 ms–2
D
0.4 ms–2
3
JEE Main 2019 (Online) 12th April Evening Slot
+4
-1
A spring whose unstretched length is l has a force constant k. The spring is cut into two pieces of unstretched lengths l1 and l2 where, l1 = nl2 and n is an integer. The ratio k1/k2 of the corresponding force constant, k1 and k2 will be :
A
$${1 \over {{n^2}}}$$
B
$${1 \over n}$$
C
n2
D
n
4
JEE Main 2019 (Online) 10th April Evening Slot
+4
-1
A bullet of mass 20 g has an initial speed of 1 ms–1 , just before it starts penetrating a mud wall of thickness 20 cm. If the wall offers a mean resistance of 2.5 × 10–2 N, the speed of the bullet after emerging from the other side of the wall is close to :
A
0.3 ms-1
B
0.1 ms-1
C
0.7 ms-1
D
0.4 ms-1
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