Learn

Saturday, 31 October

JEE Main 2021 · PhysicsMultiple choiceSingle correctMediumCalculation

JEE Main 27 August 2021, Shift 1, Physics Q4

Question 4 of 90 in this shift, Physics question 4 of 30, Section A.

The resultant of these forces OP→\overrightarrow{OP}, OQ→\overrightarrow{OQ}, OR→\overrightarrow{OR}, OS→\overrightarrow{OS} and OT→\overrightarrow{OT} is approximately __________ N. [Take 3=1.7\sqrt{3}=1.7, 2=1.4\sqrt{2}=1.4 Given i^\hat{i} and j^\hat{j} unit vectors along xx, yy axis]

The figure, in words

Five force vectors from origin O with x, y axes (x', y' negative directions): OP = 20 N at 30 deg from the y axis (toward +x side); OQ = 10 N at 30 deg above the x axis; OR = 20 N toward lower right, 45 deg below the x axis; OS = 15 N toward lower left, 45 deg below x' axis; OT = 15 N toward upper left, 60 deg from the y axis (on the x' side).
  1. (1)3i^+15j^3\hat{i}+15\hat{j}
  2. (2)−1.5i^−15.5j^-1.5\hat{i}-15.5\hat{j}
  3. (3)9.25i^+5j^9.25\hat{i}+5\hat{j}Official answer
  4. (4)2.5i^−14.5j^2.5\hat{i}-14.5\hat{j}

Official answer

Option 3

NTA final key.

Chapter
Motion in a Plane
Topic
Kinematics in 2D
Idea tested
Vector Component Resolution

Same idea in other shifts

Asked 6× in all
  1. 8 Apr 2024, Shift 1 · Q51Three vectors OP→\overrightarrow{OP}, OQ→\overrightarrow{OQ} and OR→\overrightarrow{OR} each of magnitude AA are acting as shown in figure.…EasyNumerical valueHas a figure
  2. 30 Jan 2024, Shift 2 · Q51A vector has magnitude same as that of A⃗=3i^+4j^\vec{A} = 3\hat{i} + 4\hat{j} and is parallel to B⃗=4i^+3j^\vec{B} = 4\hat{i} + 3\hat{j}. The xx and yy…EasyNumerical value
  3. 15 Apr 2023, Shift 1 · Q37A vector in x−yx-y plane makes an angle of 30° with y-axis. The magnitude of y-component of vector is 232\sqrt{3}. The magnitude of…EasySingle correct
  4. 26 Aug 2021, Shift 1 · Q18The magnitude of vectors OA→\overrightarrow{OA}, OB→\overrightarrow{OB} and OC→\overrightarrow{OC} in the given figure are equal. The…MediumDiagram basedHas a figure
  5. 4 Sep 2020, Shift 1 · Q3Starting from the origin at time t=0, with initial velocity 5j^5\hat{j} ms−1^{-1}, a particle moves in the x−yx-y plane with a constant…EasySingle correct

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. This question needs a figure we do not reproduce; it is described in words above. Lumi analyses 108 of the 174 JEE Main shifts held from 2017 to 2026.