Home Courses Contact About




11. (JEE Main 2021 (Online) 17th March Evening Shift)

Two particles A and B of equal masses are suspended from two massless springs of spring constants K1 and K2 respectively. If the maximum velocities during oscillations are equal, the ratio of the amplitude of A and B is

A. K 1 K 2

B. K 1 K 2

C. K 2 K 1

D. K 2 K 1

Correct Answer is Option (D)

V max = A ω

Given, ω 1 A 1 = ω 2 A 2

We know that ω = K m

k 1 m A 1 = k 2 m A 2

A 1 A 2 = k 2 k 1

12.(JEE Main 2021 (Online) 26th February Morning Shift)

If two similar springs each of spring constant K1 are joined in series, the new spring constant and time period would be changed by a factor :

A. 1 2 , 2 2

B. 1 4 , 2 2

C. 1 2 , 2

D. 1 4 , 2

Correct Answer is Option (C)

1 K e q = 1 K 1 + 1 K 1

K e q = K 1 × K 1 K 1 + K 2 = K 1 2 2 K 1 = K 2 2

T = 2 π m K e q

= 2 π m K 1 2

= 2 π 2 m K 1

= 2 T [ where T = 2 π m K 1 ]

13. (JEE Main 2021 (Online) 25th February Evening Shift)

Two identical springs of spring constant '2k' are attached to a block of mass m and to fixed support (see figure). When the mass is displaced from equilibrium position on either side, it executes simple harmonic motion. The time period of oscillations of this system is :

JEE Main 2021 (Online) 25th February Evening Shift Physics - Simple Harmonic Motion Question 73 English

A. 2 π m k

B. π m k

C. 2 π m 2 k

D. π m 2 k

Correct Answer is Option (B)

Due to parallel combination Keff = 2k + 2k = 4k

T = 2 π m k e f f

= 2 π m 4 k

T = π m k

14. (JEE Main 2021 (Online) 24th February Evening Shift)

In the given figure, a body of mass M is held between two massless springs, on a smooth inclined plane. The free ends of the springs are attached to firm supports. If each spring has spring constant k, the frequency of oscillation of given body is :

JEE Main 2021 (Online) 24th February Evening Shift Physics - Simple Harmonic Motion Question 77 English

A. 1 2 π 2 k M g sin α

B. 1 2 π k M g sin α

C. 1 2 π 2 k M

D. 1 2 π k 2 M

Correct Answer is Option (C)

Let T be the time period of oscillation, then

T = 2 π M k e q

T = 2 π M 2 k [ k e q = k + k ]

JEE Main 2021 (Online) 24th February Evening Shift Physics - Simple Harmonic Motion Question 77 English Explanation
and frequency ( f ) = 1 T = 1 2 π 2 k M

15. (JEE Main 2021 (Online) 24th February Morning Shift)

In the given figure, a mass M is attached to a horizontal spring which is fixed on one side to a rigid support. The spring constant of the spring is k. The mass oscillates on a frictionless surface with time period T and amplitude A. When the mass is in equilibrium position, as shown in the figure, another mass m is gently fixed upon it. The new amplitude of oscillations will be :

JEE Main 2021 (Online) 24th February Morning Shift Physics - Simple Harmonic Motion Question 78 English

A. A M M m

B. A M m M

C. A M + m M

D. A M M + m

Correct Answer is Option (D)

Given, initial amplitude = A

Velocity at mean position, v = A ω

Applying conservation of momentum at mean position, we get

M1v1 = M2v2

MA ω = (M + m)v'

v = M A ω M + m = M A k M M + m

v = A ω = A k M + m

A = M A k M M + m × M + m k

A = M M + m A