JEE Main 2021 · PhysicsMultiple choiceSingle correctMediumCalculation

JEE Main 31 August 2021, Shift 2, Physics Q8

Question 8 of 90 in this shift, Physics question 8 of 30, Section A.

A block moving horizontally on a smooth surface with a speed of

40

m/s splits into two parts with masses in the ratio of

1:2

. If the smaller part moves at

60

m/s in the same direction, then the fractional change in kinetic energy is :

(1) $\frac{1}{8}$ Official answer
(2) $\frac{1}{4}$
(3) $\frac{1}{3}$
(4) $\frac{2}{3}$

Official answer

Option 1

NTA final key.

Chapter: System of Particles and Rotational Motion
Topic: Collisions
Idea tested: Momentum in Explosions

Same idea in other shifts

Asked 7× in all

8 Apr 2024, Shift 1 · Q33A stationary particle breaks into two parts of masses $m_A$ and $m_B$ which move with velocities $v_A$ and $v_B$ respectively. The ratio…EasySingle correct
31 Jan 2024, Shift 1 · Q35An artillery piece of mass $M_1$ fires a shell of mass $M_2$ horizontally. Instantaneously after the firing, the ratio of kinetic energy…EasySingle correct
30 Jul 2022, Shift 2 · Q29A body moving horizontally on a smooth surface with a speed of 20 ms $^{-1}$ splits into two parts and continue to move in the same…MediumNumerical value
29 Jun 2022, Shift 1 · Q32A body of mass M at rest explodes into three pieces, in the ratio of masses $1 : 1 : 2$ . Two smaller pieces fly off perpendicular to each…EasySingle correct
22 Jul 2021, Shift 2 · Q15A bullet of ‘4 g’ mass is fired from a gun of mass 4 kg. If the bullet moves with the muzzle speed of $50\ \mathrm{ms^{-1}}$ , the impulse…EasySingle correct
18 Mar 2021, Shift 1 · Q22A ball of mass 10 kg moving with a velocity $10\sqrt{3}$ m/s along the $x$ -axis, hits another ball of mass 20 kg which is at rest. After…MediumNumerical valueHas a figure

Question text from the official JEE Main paper published by NTA; answer from the final answer key. Chapter, topic and idea tags, difficulty and skill are Lumi’s. Lumi analyses 108 of the 174 JEE Main shifts held from 2017 to 2026.