1
JEE Main 2021 (Online) 17th March Morning Shift
+4
-1
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 v. If the coefficient of static friction between the tyres and the track is $$\mu$$s, then the magnitude of negative lift FL acting downwards on the car is : (Assume forces on the four tyres are identical and g = acceleration due to gravity)

A
$$m\left( {g - {{{v^2}} \over {{\mu _s}R}}} \right)$$
B
$$- m\left( {g + {{{v^2}} \over {{\mu _s}R}}} \right)$$
C
$$m\left( {{{{v^2}} \over {{\mu _s}R}} - g} \right)$$
D
$$m\left( {{{{v^2}} \over {{\mu _s}R}} + g} \right)$$
2
JEE Main 2021 (Online) 16th March Evening Shift
+4
-1
Statement I : A cyclist is moving on an unbanked road with a speed of 7 kmh$$-$$1 and takes a sharp circular turn along a path of radius of 2m without reducing the speed. The static friction coefficient is 0.2. The cyclist will not slip and pass the curve. (g = 9.8 m/s2)

Statement II : If the road is banked at an angle of 45$$^\circ$$, cyclist can cross the curve of 2m radius with the speed of 18.5 kmh$$-$$1 without slipping.

In the light of the above statements, choose the correct answer from the options given below.
A
Statement I is incorrect and statement II is correct
B
Both statement I and statement II are true
C
Statement I is correct and statement II is incorrect
D
Both statement I and statement II are false
3
JEE Main 2021 (Online) 16th March Morning Shift
+4
-1
A block of 200 g mass moves with a uniform speed in a horizontal circular groove, with vertical side walls of radius 20 cm. If the block takes 40 s to complete one round, the normal force by the side walls of the groove is :
A
9.859 $$\times$$ 10$$-$$2 N
B
0.0314 N
C
9.859 $$\times$$ 10$$-$$4 N
D
6.28 $$\times$$ 10$$-$$3 N
4
JEE Main 2021 (Online) 26th February Morning Shift
+4
-1
A particle is moving with uniform speed along the circumference of a circle of radius R under the action of a central fictitious force F which is inversely proportional to R3. Its time period of revolution will be given by :
A
$$T \propto {R^{{4 \over 3}}}$$
B
$$T \propto {R^{{5 \over 2}}}$$
C
$$T \propto {R^{{3 \over 2}}}$$
D
$$T \propto {R^2}$$
EXAM MAP
Medical
NEET