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NEET PHYSICSEasy

A car of mass mm is moving on a level circular track of radius RR. If μs\mu_s represents the static friction between the road and tyres of the car, then the maximum speed of the car in circular motion is given by:

A

μsmRg\sqrt{\mu_s mRg}

B

Rgμs\sqrt{\frac{Rg}{\mu_s}}

C

mRgμs\sqrt{\frac{mRg}{\mu_s}}

D

μsRg\sqrt{\mu_s Rg}

Step-by-Step Solution

  1. Forces on a Level Road: On a level circular road, the vertical forces (weight mgmg and normal reaction NN) balance each other, so N=mgN = mg. The necessary centripetal force required for the car to move in a circle of radius RR is provided solely by the static friction (fsf_s) between the tyres and the road.
  2. Centripetal Force Condition: The centripetal force is given by Fc=mv2RF_c = \frac{mv^2}{R}. This force must be less than or equal to the maximum static friction (fs,maxf_{s,max}) to prevent skidding. mv2Rfs,max\frac{mv^2}{R} \le f_{s,max} fs,max=μsN=μsmgf_{s,max} = \mu_s N = \mu_s mg
  3. Derivation: mv2Rμsmg\frac{mv^2}{R} \le \mu_s mg v2μsRgv^2 \le \mu_s Rg vμsRgv \le \sqrt{\mu_s Rg} Therefore, the maximum speed is vmax=μsRgv_{max} = \sqrt{\mu_s Rg}. (Reference: NCERT Class 11, Physics Part I, Chapter 5, Section 5.10, Eq. 4.18).
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