The maximum velocity (in ms-1) with which a car driver must traverse a flat curve of radius 150 m and coefficient of friction 0.6 to avoid skidding is
60
30
15
25
A block of 10 kg is pulled at a constant speed on a rough horizontal surface by a force of 20 N.Find the co- effecient of kinetic friction .Given that g = 10 m/s2 .
0.2
0.5
0.85
0.7
Friction is the result of
gravitational acceleration
molecular interaction
magnetic interaction
nuclear interaction
Three blocks of masses 2 kg, 3 kg and 5 kg are connected to each other with light string and are then placed on a frictionless surface as shown in figure. The system is pulled by a force F=10N, then tension T1 is
1N
5 N
8 N
10N
A weight W rests on a rough horizontal plane. If the angle of friction be θ, the least force that will move the body along the plane will be
W cosθ
W tanθ
W cotθ
W sinθ
A block of mass 2 kg rests on a rough inclined plane making an angle 300 with the horizontal. The coefficient of static friction between the block and the plane is 0.7. The frictional force on the block is
9.8 N
0.7×9.8 N
A block of mass 0.1 kg is held against a wall applying a horizontal force of 5 N on the block. If the co-efficient of friction between the block and the wall is 0.5, the magnitude of the frictional force acting on the block is
2.5 N
0.98 N
4.9 N
0.49 N
A block of metal of mass 2 kg is resting on a frictionless floor.It is struck by a jet releasing water at the rate of 1 kg/sec and at a speed of 5 m/s.What will be the initial acceleration of the block ?
3.5 m/s2
4.5 m/s2
2.5 m/s2
none of these
A marble block of mass 2 kg lying on ice, when given a velocity of 6 ms-1, is stopped by friction in 10 s. Then the coefficient of friction is
0.02
0.03
0.06
0.01
Assertion (A): Frictional forces are conservative forces.Reason(R): Potential energy can be associated with frictional forces.
Both A and R are true and R is the correct explanation of A
Both A and R are true but R is not correct explanation of A
A is true,but R is false
Both A and R are false
