1
JEE Main 2021 (Online) 31st August Evening Shift
+4
-1
Four identical hollow cylindrical columns of mild steel support a big structure of mass 50 $$\times$$ 103 kg. The inner and outer radii of each column are 50 cm and 100 cm respectively. Assuming uniform local distribution, calculate the compression strain of each column. [Use Y = 2.0 $$\times$$ 1011 Pa, g = 9.8 m/s2]
A
3.60 $$\times$$ 10$$-$$8
B
2.60 $$\times$$ 10$$-$$7
C
1.87 $$\times$$ 10$$-$$3
D
7.07 $$\times$$ 10$$-$$4
2
JEE Main 2021 (Online) 31st August Morning Shift
+4
-1
A uniform heavy rod of weight 10 kg ms$$-$$2, cross-sectional area 100 cm2 and length 20 cm is hanging from a fixed support. Young modulus of the material of the rod is 2 $$\times$$ 1011 Nm$$-$$2. Neglecting the lateral contraction, find the elongation of rod due to its own weight.
A
2 $$\times$$ 10$$-$$9 m
B
5 $$\times$$ 10$$-$$8 m
C
4 $$\times$$ 10$$-$$8 m
D
5 $$\times$$ 10$$-$$10 m
3
JEE Main 2021 (Online) 27th August Morning Shift
+4
-1
In Millikan's oil drop experiment, what is viscous force acting on an uncharged drop of radius 2.0 $$\times$$ 10$$-$$5 m and density 1.2 $$\times$$ 103 kgm$$-$$3 ? Take viscosity of liquid = 1.8 $$\times$$ 10$$-$$5 Nsm$$-$$2. (Neglect buoyancy due to air).
A
3.8 $$\times$$ 10$$-$$11 N
B
3.9 $$\times$$ 10$$-$$10 N
C
1.8 $$\times$$ 10$$-$$10 N
D
5.8 $$\times$$ 10$$-$$10 N
4
JEE Main 2021 (Online) 26th August Evening Shift
+4
-1
Two blocks of masses 3 kg and 5 kg are connected by a metal wire going over a smooth pulley. The breaking stress of the metal is $${{24} \over \pi } \times {10^2}$$ Nm-2. What is the minimum radius of the wire ? (Take g = 10 ms-2)

A
125 cm
B
1250 cm
C
12.5 cm
D
1.25 cm
EXAM MAP
Medical
NEET