JEE Main 2020 · PhysicsMultiple choiceSingle correctMediumCalculation

JEE Main 9 January 2020, Shift 1, Physics Q3

Question 3 of 75 in this shift, Physics question 3 of 25, Section A.

Two particles of equal mass m have respective initial velocities

u\hat{i}

and

u\left(\frac{\hat{i}+\hat{j}}{2}\right)

. They collide completely inelastically. The energy lost in the process is :

(1) $\frac{1}{8}mu^{2}$ Official answer
(2) $\frac{3}{4}mu^{2}$
(3) $\sqrt{\frac{2}{3}}\,mu^{2}$
(4) $\frac{1}{3}mu^{2}$

Official answer

Option 1

NTA final key (Jan 2020).

Chapter: Work, Energy and Power
Topic: Collisions
Idea tested: Inelastic Collisions

Same idea in other shifts

Asked 7× in all

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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.