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Saturday, 31 October

JEE Main 2021 · PhysicsMultiple choiceDiagram basedMediumApplication

JEE Main 17 March 2021, Shift 1, Physics Q2

Question 2 of 90 in this shift, Physics question 2 of 30, Section A.

A modern grand - prix racing car of mass m is travelling on a flat track in a circular arc of radius R with a speed vv. If the coefficient of static friction between the tyres and the track is μs\mu_s, then the magnitude of negative lift FLF_L acting downwards on the car is : (Assume forces on the four tyres are identical and g = acceleration due to gravity)

The figure, in words

Part of a circular track drawn as two concentric arcs (a curved track strip) with a centre point; a dashed radius labelled R runs from the centre to the track, a solid horizontal line from the centre also labelled R, and an arrow labelled v at the top of the arc pointing tangentially along the track.
  1. (1)m(v2μsR+g)m\left(\frac{v^2}{\mu_sR}+g\right)
  2. (2)m(g−v2μsR)m\left(g-\frac{v^2}{\mu_sR}\right)
  3. (3)m(v2μsR−g)m\left(\frac{v^2}{\mu_sR}-g\right)Official answer
  4. (4)−m(g+v2μsR)-m\left(g+\frac{v^2}{\mu_sR}\right)

Official answer

Option 3

NTA final key.

Chapter
Laws of Motion
Topic
Circular Motion
Idea tested
Banking of Roads

Same idea in other shifts

Asked 2× in all
  1. 27 Jan 2024, Shift 1 · Q34A train is moving with a speed of 12 m/s on rails which are 1.5 m apart. To negotiate a curve of radius 400 m, the height by which the…MediumSingle 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.