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JEE Mains Previous Years Questions with Solutions

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1

JEE Main 2021 (Online) 31st August Morning Shift

MCQ (Single Correct Answer)
Angular momentum of a single particle moving with constant speed along circular path :
A
changes in magnitude but remains same in the direction
B
remains same in magnitude and direction
C
remains same in magnitude but changes in the direction
D
is zero

Explanation


$$\left| {\overrightarrow L } \right|$$ = mvr

And direction will be upward & remain constant.

Option (b)
2

JEE Main 2021 (Online) 31st August Morning Shift

MCQ (Single Correct Answer)
A body of mass M moving at speed V0 collides elastically with a mass 'm' at rest. After the collision, the two masses move at angles $$\theta$$1 and $$\theta$$2 with respect to the initial direction of motion of the body of mass M. The largest possible value of the ratio M/m, for which the angles $$\theta$$1 and $$\theta$$2 will be equal, is :
A
4
B
1
C
3
D
2

Explanation


Given $$\theta$$1 = $$\theta$$2 = $$\theta$$

from momentum conservation

in x-direction MV0 = MV1 cos$$\theta$$ + mV2 cos$$\theta$$

in y-direction 0 = MV1 sin$$\theta$$ $$-$$ mV2 sin$$\theta$$

Solving above equations

$${V_2} = {{M{V_1}} \over m}$$, V0 = 2V1 cos$$\theta$$

From energy conservation

$${1 \over 2}MV_0^2 = {1 \over 2}MV_1^2 + {1 \over 2}MV_2^2$$

Substituting value of V2 & V0, we will get

$${M \over m} + 1 = 4{\cos ^2}\theta \le 4$$

$${M \over m} \le 3$$

Option (c)
3

JEE Main 2021 (Online) 27th August Morning Shift

MCQ (Single Correct Answer)
Moment of inertia of a square plate of side l about the axis passing through one of the corner and perpendicular to the plane of square plate is given by :
A
$${{M{l^2}} \over 6}$$
B
$${M{l^2}}$$
C
$${{M{l^2}} \over {12}}$$
D
$${2 \over 3}M{l^2}$$

Explanation

According to perpendicular Axis theorem.


Ix + Iy = Iz

Iz $$\Rightarrow$$ $${{m{l^2}} \over 3} + {{m{l^2}} \over 3}$$

$$ = {{2m{l^2}} \over 3}$$
4

JEE Main 2021 (Online) 26th August Evening Shift

MCQ (Single Correct Answer)
A particle of mass m is suspended from a ceiling through a string of length L. The particle moves in a horizontal circle of radius r such that $$r = {L \over {\sqrt 2 }}$$. The speed of particle will be :
A
$${\sqrt {rg} }$$
B
$${\sqrt {2rg} }$$
C
$${2\sqrt {rg} }$$
D
$${\sqrt {{{rg} \over 2}} }$$

Explanation



$$r = {l \over {\sqrt 2 }}$$

$$\sin \theta = {r \over l} = {l \over {\sqrt 2 }}$$

$$\theta$$ = 45$$^\circ$$

$$T\sin \theta = {{m{v^2}} \over r}$$

$$T\cos \theta = mg$$

$$\tan \theta = {{{v^2}} \over {rg}} \Rightarrow v = \sqrt {rg} $$

Questions Asked from Impulse & Momentum

On those following papers in MCQ (Single Correct Answer)
Number in Brackets after Paper Indicates No. of Questions
JEE Main 2021 (Online) 31st August Morning Shift (2)
JEE Main 2021 (Online) 27th August Morning Shift (1)
JEE Main 2021 (Online) 26th August Evening Shift (1)
JEE Main 2021 (Online) 27th July Morning Shift (2)
JEE Main 2021 (Online) 25th July Morning Shift (1)
JEE Main 2021 (Online) 22th July Evening Shift (1)
JEE Main 2021 (Online) 20th July Evening Shift (1)
JEE Main 2021 (Online) 18th March Evening Shift (1)
JEE Main 2021 (Online) 17th March Evening Shift (1)
JEE Main 2021 (Online) 17th March Morning Shift (1)
JEE Main 2021 (Online) 16th March Evening Shift (1)
JEE Main 2021 (Online) 16th March Morning Shift (1)
JEE Main 2021 (Online) 26th February Morning Shift (1)
JEE Main 2020 (Online) 6th September Evening Slot (1)
JEE Main 2020 (Online) 3rd September Morning Slot (1)
JEE Main 2020 (Online) 9th January Evening Slot (1)
JEE Main 2020 (Online) 9th January Morning Slot (1)
JEE Main 2019 (Online) 12th April Evening Slot (1)
JEE Main 2019 (Online) 12th April Morning Slot (1)
JEE Main 2019 (Online) 10th April Evening Slot (2)
JEE Main 2019 (Online) 10th April Morning Slot (3)
JEE Main 2019 (Online) 9th April Evening Slot (1)
JEE Main 2019 (Online) 9th April Morning Slot (2)
JEE Main 2019 (Online) 8th April Evening Slot (2)
JEE Main 2019 (Online) 8th April Morning Slot (1)
JEE Main 2019 (Online) 12th January Morning Slot (2)
JEE Main 2019 (Online) 11th January Evening Slot (1)
JEE Main 2019 (Online) 10th January Evening Slot (1)
JEE Main 2019 (Online) 9th January Morning Slot (1)
JEE Main 2018 (Online) 15th April Morning Slot (1)
JEE Main 2015 (Offline) (1)
JEE Main 2013 (Offline) (1)
AIEEE 2010 (2)
AIEEE 2006 (1)
AIEEE 2005 (1)
AIEEE 2004 (1)

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