Understanding frictional forces

A coefficient of friction μ and the angle of friction θ are related as

A) sinθ = μ

B) cosθ = μ

C) tanθ = μ

D) tanμ = θ 

A block of 1 kg is stopped against a wall by applying a force F perpendicular to the wall. If μ = 0.2, then minimum value of F will be

Maximum value of static friction is called limiting friction.

A) True

B) False

C) Ambigunous

D) Data insufficient

The work done by a frictional force is:

A) Can be zero

B) Can be positive

C) Can be negavtive

D) All of the above

The maximum static frictional force is limiting friction.

A) True

B) False

C) Ambigunous

D) Data insufficient 

A 60 kg body is pushed with just enough force to start it moving across a floor and the same force continues to act afterwards .The coefficient of static friction and sliding friction is 0.5 and 0.4 respectively. The acceleration of the body is

A car of mass m negotiating a curved path of radius of curvature r with a speed v. If μ is necessary minimum coefficient of friction between tyres of car and road so that the vehle does not skid. What is the minimum velocity for not skidding the car.

A horizontal force of 129.4 N is applied on a 10 kg block which rests on a horizontal surface. If the coefficient of friction is  0.3, the acceleration  should be

A) 9.8 m/sec²

B) 10 m/sec²

C) 12 m/sec²

D) 19.6 m/sec²

Which one of the following statement is correct.

A) Rolling friction is greater than sliding friction

B) Rolling friction is less than sliding friction

C) Rolling friction is equal to sliding friction

D) Rolling friction and sliding friction are same 

A force of 98 N is required to just start moving a body of mass 100 kg over ice. The coefficient of  stafriction is (g =10 m/sec²)

A) 0.6

B) 0.4

C) 0.2

D) 0.1

When two surfaces are coated with the lubricant, then they will:

A) Slide upon each other

B) Stick to each other

C) Roll upon each other

D) Jump upon each other

A body is moving on a surface, the force of friction is called

A) Static friction

B) dynamic friction

C) Limiting friction

D) Rolling friction

It is easier to roll a barrel then pull it along the road. This statement is

A) False

B) True

C) Uncertain

D) Not Possible

Which is the suitable method to reduce friction:

A) Ball and bearings

B) Lubrcation

C) Polishing

D) All of the above

A boy of mass 40 kg is climbing a vertical pole at a constant speed. If the coefficient of friction his palm and the pole is 0.8 and g = 10 m/sec², the horizontal force that he is applying on the pole is

A) 300 N

B) 400 N

C) 500 N

D) 600 N