1
JEE Main 2025 (Online) 7th April Morning Shift
MCQ (Single Correct Answer)
+4
-1

A rod of length 5 L is bent right angle keeping one side length as 2 L .

JEE Main 2025 (Online) 7th April Morning Shift Physics - Center of Mass and Collision Question 2 English

The position of the centre of mass of the system :

(Consider $\mathrm{L}=10 \mathrm{~cm}$)

A
$4 \hat{i}+9 \hat{j}$
B
$2 \hat{i}+3 \hat{j}$
C
$5 \hat{i}+8 \hat{j}$
D
$3 \hat{i}+7 \hat{j}$
2
JEE Main 2025 (Online) 3rd April Evening Shift
MCQ (Single Correct Answer)
+4
-1
JEE Main 2025 (Online) 3rd April Evening Shift Physics - Center of Mass and Collision Question 1 English

Consider two blocks A and B of masses $m_1=10 \mathrm{~kg}$ and $\mathrm{m}_2=5 \mathrm{~kg}$ that are placed on a frictionless table. The block A moves with a constant speed $v=3 \mathrm{~m} / \mathrm{s}$ towards the block B kept at rest. A spring with spring constant $\mathrm{k}=3000 \mathrm{~N} / \mathrm{m}$ is attached with the block B as shown in the figure. After the collision, suppose that the blocks A and B, along with the spring in constant compression state, move together, then the compression in the spring is, (Neglect the mass of the spring)

A
0 .3 m
B
0.1 m
C
0.4 m
D
0.2 m
3
JEE Main 2025 (Online) 29th January Evening Shift
MCQ (Single Correct Answer)
+4
-1
Change Language

JEE Main 2025 (Online) 29th January Evening Shift Physics - Center of Mass and Collision Question 7 English

Three equal masses $m$ are kept at vertices $(A, B, C)$ of an equilateral triangle of side a in free space. At $t=0$, they are given an initial velocity $\overrightarrow{V_A}=V_0 \overrightarrow{A C}, \overrightarrow{V_B}=V_0 \overrightarrow{B A}$ and $\overrightarrow{V_C}=V_0 \overrightarrow{C B}$. Here, $\overrightarrow{A C}, \overrightarrow{C B}$ and $\overrightarrow{B A}$ are unit vectors along the edges of the triangle. If the three masses interact gravitationally, then the magnitude of the net angular momentum of the system at the point of collision is :

A
$\frac{1}{2}$ a $\mathrm{mV}_0$
B
3 a $\mathrm{mV}_0$
C
$\frac{3}{2}$ a $\mathrm{mV}_0$
D
$\frac{\sqrt{3}}{2}$ a $\mathrm{m}V_0$
4
JEE Main 2025 (Online) 29th January Evening Shift
MCQ (Single Correct Answer)
+4
-1
Change Language

Given below are two statements. One is labelled as Assertion (A) and the other is labelled as Reason (R).

Assertion (A): JEE Main 2025 (Online) 29th January Evening Shift Physics - Center of Mass and Collision Question 6 English Three identical spheres of same mass undergo one dimensional motion as shown in figure with initial velocities $v_{\mathrm{A}}=5 \mathrm{~m} / \mathrm{s}, v_{\mathrm{B}}=2 \mathrm{~m} / \mathrm{s}, v_{\mathrm{C}}=4 \mathrm{~m} / \mathrm{s}$. If we wait sufficiently long for elastic collision to happen, then $v_{\mathrm{A}}=4 \mathrm{~m} / \mathrm{s}, v_{\mathrm{B}}=2 \mathrm{~m} / \mathrm{s}$, $v_{\mathrm{C}}=5 \mathrm{~m} / \mathrm{s}$ will be the final velocities.

Reason (R): In an elastic collision between identical masses, two objects exchange their velocities.

In the light of the above statements, choose the correct answer from the options given below:

A

Both (A) and (R) are true but (R) is NOT the correct explanation of (A)

B

Both (A) and (R) are true and (R) is the correct explanation of (A)

C

(A) is false but (R) is true

D

(A) is true but (R) is false

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