Friction Practice Level - 1 - Class 11 MCQ

Two blocks of masses M₁ and M₂ are connected witha string which passes over a smooth pulley. The massM₁ is placed on a rough incline plane as shown in thefigure. The coefficient of friction between the block andthe inclined plane is μ. What should be the minimummass M₂ so that the block M₁ slides upwards?

A box of mass 8 kg is placed on a rough inclined planeof inclination q . Its downward motion can be preventedby applying an upward pull F and it can be made toslide upwards by applying a force 2 F. The coefficientof friction between the box and the inclined plane is

A block of mass 15 kg is resting on a rough inclinedplane as shown in figure. The block is tied by a horizontalstring which has a tension of 50 N. The coefficient offriction between the surfaces of contact is

A horizontal force Just sufficient to move a body ofmass 4 kg lying on a rough horizontal surface, is appliedon it. The coefficient of static and kinetic frictionbetween the body and the surface are 0.8 and 0.6,respectively. If the force continues to act even after theblock has started moving, the acceleration of the blockin ms^-2 is (g = 10ms^-2)

The upper half of an inclined plane with inclination f isperfectly smooth while the lower half is rough. A bodystarting from rest at the top will again come to rest atthe bottom if the coefficient of friction for the lower halfis given by

A block of mass m is placed on another block of massM, which itself is lying on a horizontal surface. Thecoefficient of friction between two blocks is μ₁ and thatbetween the block of mass M and horizontal surfaceis μ₂. What maximum horizontal force can be appliedto the lower block so that the two blocks move withoutseparation? 

Two blocks A and B of masses 6 kg and 3 kg rest ona smooth horizontal surface as shown in the figure.If coefficient of friction between A and B is 0.4,the maximum horizontal force which can make themmove without separation is

Two blocks of masses M₁ and M₂ are connected witha string passing over a pulley as shown in figure. Theblock M₁ lies on a horizontal surface. The coefficientof friction between the block M₁ and the horizontalsurface is μ. The system accelerates. What additionalmass m should be placed on the block M₁ so thatthe system does not accelerate?

A system is pushed by a force F as shown in figure. Allsurfaces are smooth except between B and C. Frictioncoefficient between B and C is μ. Minimum value of Fto prevent block B from down ward slipping is 

A body of mass M is resting on a rough horizontalplane surface, the coefficient of friction being equal toμ. At t = 0, a horizontal force F = F₀t starts acting on it,where F₀ is a constant. Find the time T at which themotion starts?

The maximum value of mass of block C so that neitherA nor B moves is (Given that mass of A is100 kg andthat of B is 140 kg. Pulleys are smooth and frictioncoefficient between A and B and between B andhorizontal surface is μ = 0.3). Take g = 10 ms^-2.

A block A of mass 2 kg is placed over another block Bof mass 4 kg, which is placed over a smooth horizontalfloor. The coefficient of friction between A and B is 0.4.When a horizontal force of magnitude 10 N is appliedon A, the acceleration of blocks A and B are

Two blocks m and M tied together with an inextensiblestring are placed at rest on a rough horizontal surfacewith coefficient of friction μ. The block m is pulled with avariable force Fat a varying angleq with the horizontal.The value of q at which the least value of F is requiredto move the blocks is given by 

A trolley A has a simple pendulum suspended from aframe fixed to its desk. A block B is in contact on itsvertical slide. The trolley is on horizontal rails andaccelerates towards the right such that the block is just prevented from falling. The value of coefficient offriction between A and B is 0.5. The inclination of thependulum to the vertical is  

A body of mass m is launched up on a rough inclinedplane making an angle 45° with horizontal. If the timeof ascent is half of the time of descent, thefrictional coefficient between plane and body is

A wooden block of mass M resting on a roughhorizontal floor is pulled with a force F at an anglefwith the horizontal. If μ is the coefficient of kineticfriction between the block and the surface, then theacceleration of the block is

A given object takes n times more time to slide down45° rough inclined plane as it takes to slide down aperfectly smooth 45° incline. The coefficient of kineticfriction between the object and the incline is