CRACKNEETPhysics

JEE Advanced Question Practise

A smooth spherical ball strikes a smooth horizontal surface with speed u making an angle α with the horizontal. After collision, it rebounds with speed v making an angle β with the horizontal. The coefficient of restitution between the ball and the surface is e.


Which of the following relations is correct?

Options:
(A) v sin β = e u sin α
(B) v cos β = e u cos α
(C) v² = e u²
(D) tan β = e tan α

4 hours ago | [YT] | 0

CRACKNEETPhysics

JEE Advanced Physics: The Variable Dielectric Challenge

A parallel plate capacitor is filled with a dielectric whose relative permittivity varies with the applied voltage U as εᵣ = αU, where α = 2 V⁻¹. A similar identical capacitor with no dielectric is charged to U₀ = 78 V. It is then connected in parallel to the uncharged capacitor containing the dielectric. What is the final common voltage (U_f) across the capacitors?

A) 6 V

B) 8.4 V

C) 13.2 V

D) 39 V

Answer :https://youtu.be/sMM-kYdV7OU?si=7l71k...

1 day ago | [YT] | 6

CRACKNEETPhysics

JEE Advanced Practice


An ant starts moving from an ant-hill (origin) along a straight line. Its velocity v is found to be inversely proportional to its distance r from the center of the ant-hill (v = k / r). At a distance L = 1 m, the ant's velocity is measured to be v₀ = 2 cm/s.

A second ant starts from the origin (ant-hill) at rest (u = 0) at the same moment the first ant passes point A (distance L = 1 m). Both ants reach point B (distance 2L = 2 m) at the exact same time T.

Which of the following statements regarding this motion is/are CORRECT?

(Take k = 0.02 m²/s; assume the second ant moves with constant acceleration a)

A) The first ant moves with a constant acceleration of -0.5 × 10⁻⁴ m/s².

B) The magnitude of the first ant's acceleration at point B is 5 × 10⁻⁵ m/s².

C) The constant acceleration a of the second ant is 4 / 5625 m/s².

D) The velocity of the first ant when it is exactly halfway between A and B (r = 1.5 m) is 1.33 cm/s.

1 day ago | [YT] | 4

CRACKNEETPhysics

JEE Advanced Practice: Part 1 (Single Correct MCQ)

An ant starts moving from an ant-hill along a straight line such that its velocity v is inversely proportional to its distance r from the center of the ant-hill (v = k / r). At a distance L = 1 m, its velocity is measured to be v₀ = 2 cm/s.

The ant travels from point A (at distance L) to point B (at distance 2L). What is the total time T taken for this journey?

A) 50 seconds

B) 75 seconds

C) 100 seconds

D) 150 seconds

NUMERICAL PRACTISE ON CALCULAS BASED MOTION IN STRAIGHT LINE USEFUL FOR NEET/JEE MAINS AND JEE ADVANCED : youtube.com/live/LMgu0y5O5w4

1 day ago | [YT] | 1

CRACKNEETPhysics

JEE ADVANCED PRACTISE QUESTION

An electric lift of mass 2000 kg moves upward under gravity (take g = 10 m/s²). The frictional force opposing motion increases linearly with height as

F(y) = 50y N,

where y is the vertical displacement in meters.

The velocity of the lift varies with height according to

v(y) = 1.5 (1 + y/R) m/s,

where R is a constant length scale.

Determine the height y at which the power delivered by the motor attains its maximum value in the interval 0 ≤ y ≤ H.


(A) Power is maximum at y = 0
(B) Power is maximum at y = H
(C) Power is maximum at y = R/2
(D) Power is maximum at y = √R

Work Power Energy Numerical Practise: youtube.com/live/SX3sJFFm5R4

3 days ago | [YT] | 0

CRACKNEETPhysics

JEE ADVANCED PRACTISE QUESTION

A block of weight W rests on a rough inclined plane at angle α with coefficient of static friction μ. The block is connected to a string parallel to the incline with tension T.

The block can remain in equilibrium only if the tension lies within a certain range. Further, consider the lower limit of this range as a function of α.

Which of the following options correctly state both the permissible range of tension and the angle at which the lower limit of tension attains its maximum value?

(A) W sin α − μW cos α ≤ T ≤ W sin α + μW cos α; maximum lower limit at α = tan⁻¹(μ)

(B) W cos α − μW sin α ≤ T ≤ W cos α + μW sin α; maximum lower limit at α = cot⁻¹(μ)

(C) W sin α − μW cos α ≤ T ≤ W sin α + μW cos α; maximum lower limit at α = cot⁻¹(μ)

(D) W cos α − μW sin α ≤ T ≤ W cos α + μW sin α; maximum lower limit at


Answer in this Video: https://youtu.be/-yZB3Iybeok

3 days ago | [YT] | 4

CRACKNEETPhysics

PHYSICS PRACTISE QUESTION

A particle moves in a circle of radius 2 m with an initial velocity vector of 4 î m/s along the +x axis. The centripetal acceleration is directed inward. After 1 second of motion, what is the final velocity vector of the particle?

(A) 4 î + 8 ĵ m/s
(B) 4 î − 8 ĵ m/s
(C) 8 î − 4 ĵ m/s
(D) −4 î + 8 ĵ m/s

Theory of Centripetal Acceleration: https://youtu.be/ydoKpU_pqyA

3 days ago | [YT] | 4

CRACKNEETPhysics

PHYSICS PRACTISE QUESTION

A particle tied to a string is moving in a vertical circle. The motion becomes incomplete when the centripetal force is insufficient to keep the particle on the circular path.

Which of the following statements correctly describe what happens when tension in the string falls to zero?

(A) The particle continues circular motion with reduced radius because gravity alone maintains the centripetal pull.
(B) The particle leaves the circular path and may move tangentially under gravity’s influence.
(C) The particle may exhibit simple harmonic motion if a restoring force arises (e.g., string snagging or pendulum‑like swing).
(D) The particle remains stationary at the point where tension vanishes, since no force acts on it.

NON-UNIFORM CIRCULAR MOTION: www.youtube.com/playlist?list...

3 days ago | [YT] | 2

CRACKNEETPhysics

PHYSICS PRACTISE QUESTION

Assertion (A):
In disrupted vertical circular motion, the total mechanical energy (kinetic + potential) of the particle remains conserved if no external work is done.

Reason (R):
This is because tension in the string always performs positive work, thereby increasing the total mechanical energy of the system.

Options
(A) Both A and R are true, and R is the correct explanation of A
(B) Both A and R are true, but R is not the correct explanation of A
(C) A is true, but R is false
(D) A is false, but R is true

Concept and Theory: https://youtu.be/hUEd9p0gH40

3 days ago | [YT] | 2

CRACKNEETPhysics

PHYSICS PRACTISE QUESTIONS

A particle tied to a string is moving in a vertical circle. At some point, the tension in the string becomes zero due to insufficient velocity, and the particle leaves the circular path.

Which of the following statements correctly describes the subsequent motion?

(A) The particle will continue uniform circular motion with reduced radius.
(B) The particle will move tangentially in a straight line with constant speed.
(C) The particle may exhibit simple harmonic motion if a restoring force acts towards a mean position.
(D) The particle will remain at rest at the point where tension vanishes.

Concept and Theory : https://youtu.be/hUEd9p0gH40

3 days ago | [YT] | 2