Friction Test 1

Total Questions:25 Total Time: 45 Min

Remaining:

Questions 1 of 25

Question:A force of 98 N is required to just start moving a body of mass 100 kg over ice. The coefficient of static friction is

0.6

0.4

0.2

0.1

Questions 2 of 25

Question:A block weighs W is held against a vertical wall by applying a horizontal force F. The minimum value of F needed to hold the block is

Less than W

Equal to W

Greater than W

Data is insufficient

Questions 3 of 25

Question:The maximum static frictional force is

Equal to twice the area of surface in contact

Independent of the area of surface in contact

Equal to the area of surface in contact

None of the above

Questions 4 of 25

Question:Maximum value of static friction is called

Limiting friction

Rolling friction

Normal reaction

Coefficient of friction

Questions 5 of 25

Question:Pulling force making an angle $$\theta$$ to the horizontal is applied on a block of weight W placed on a horizontal table. If the angle of friction is $$\alpha$$, then the magnitude of force required to move the body is equal to

$$\frac{{W\sin \alpha }}{{g\tan (\theta - \alpha )}}$$

$$\frac{{W\cos \alpha }}{{\cos (\theta - \alpha )}}$$

$$\frac{{W\sin \alpha }}{{\cos (\theta - \alpha )}}$$

$$\frac{{W\tan \alpha }}{{\sin (\theta - \alpha )}}$$

Questions 6 of 25

Question:When two surfaces are coated with a lubricant, then they

Stick to each other

Slide upon each other

Roll upon each other

None of these

Questions 7 of 25

Question:A 20 kg block is initially at rest on a rough horizontal surface. A horizontal force of 75 N is required to set the block in motion. After it is in motion, a horizontal force of 60 N is required to keep the block moving with constant speed. The coefficient of static friction is

0.38

0.44

0.52

0.6

Questions 8 of 25

Question:A block A with mass 100 kg is resting on another block B of mass 200 kg. As shown in figure a horizontal rope tied to a wall holds it. The coefficient of friction between A and B is 0.2 while coefficient of friction between B and the ground is 0.3. The minimum required force F to start moving B will be

900 N

100 N

1100 N

1200 N

Questions 9 of 25

Question:To avoid slipping while walking on ice, one should take smaller steps because of the

Friction of ice is large

Larger normal reaction

Friction of ice is small

Smaller normal reaction

Questions 10 of 25

Question:The maximum speed that can be achieved without skidding by a car on a circular unbanked road of radius R and coefficient of static friction $$\mu$$, is

$$\mu Rg$$

$$Rg\sqrt \mu$$

$$\mu \sqrt {Rg}$$

$$\sqrt {\mu Rg}$$

Questions 11 of 25

Question:A car is moving along a straight horizontal road with a speed $${v_0}$$. If the coefficient of friction between the tyres and the road is $$\mu$$, the shortest distance in which the car can be stopped is

$$\frac{{v_0^2}}{{2\mu g}}$$

$$\frac{{{v_0}}}{{\mu g}}$$

$${\left( {\frac{{{v_0}}}{{\mu g}}} \right)^2}$$

$$\frac{{{v_0}}}{\mu }$$

Questions 12 of 25

Question:A block of mass 5 kg is on a rough horizontal surface and is at rest. Now a force of 24 N is imparted to it with negligible impulse. If the coefficient of kinetic friction is 0.4 and $$g = 9.8\,m/{s^2}$$, then the acceleration of the block is

$$0.26\,m/{s^2}$$

$$0.39\,m/{s^2}$$

$$0.69\,m/{s^2}$$

$$0.88\,m/{s^2}$$

Questions 13 of 25

Question:A body of mass 2 kg is being dragged with uniform velocity of 2 m/s on a rough horizontal plane. The coefficient of friction between the body and the surface is 0.20. The amount of heat generated in 5 sec is $$(J = 4.2\,joule/cal$$ and $$g = 9.8\,m/{s^2})$$

9.33 cal

10.21 cal

12.67 cal

13.34 cal

Questions 14 of 25

Question:A block of mass 50 kg slides over a horizontal distance of 1 m. If the coefficient of friction between their surfaces is 0.2, then work done against friction is

98 J

72J

56 J

34 J

Questions 15 of 25

Question:On the horizontal surface of a truck ($$\mu$$ = 0.6), a block of mass 1 kg is placed. If the truck is accelerating at the rate of 5m/sec$$^{\rm{2}}$$ then frictional force on the block will be

5 N

6 N

5.88 N

8 N

Questions 16 of 25

Question:A vehicle of mass m is moving on a rough horizontal road with momentum P. If the coefficient of friction between the tyres and the road be $$\mu$$, then the stopping distance is

$$\frac{P}{{2\mu \,m\,g}}$$

$$\frac{{{P^2}}}{{2\mu \,m\,g}}$$

$$\frac{P}{{2\mu \,m{\,^2}g}}$$

$$\frac{{{P^2}}}{{2\mu \,m{\,^2}g}}$$

Questions 17 of 25

Question:A body of weight 64 N is pushed with just enough force to start it moving across a horizontal floor and the same force continues to act afterwards. If the coefficients of static and dynamic friction are 0.6 and 0.4 respectively, the acceleration of the body will be (Acceleration due to gravity = g)

$$\frac{g}{{6.4}}$$

0.64 g

$$\frac{g}{{32}}$$

0.2 g

Questions 18 of 25

Question:A body is moving along a rough horizontal surface with an initial velocity $$6\,\,m/s.$$ If the body comes to rest after travelling 9 m, then the coefficient of sliding friction will be

0.4

0.2

0.6

0.8

Questions 19 of 25

Question:Consider a car moving on a straight road with a speed of 100 m/s. The distance at which car can be stopped is $$[{\mu _k} = 0.5]$$

100 m

400 m

800 m

1000 m

Questions 20 of 25

Question:A cylinder of 10 kg is sliding in a plane with an initial velocity of 10 m/s. If the coefficient of friction between the surface and cylinder is 0.5 then before stopping, it will cover. $$(g = 10\,\,m/{s^2})$$

2.5 m

5 m

7.5 m

10 m

Questions 21 of 25

Question:When a body is lying on a rough inclined plane and does not move, the force of friction

is equal to $$\mu R$$

is less than $$\mu R$$

is greater than $$\mu R$$

is equal to R

Questions 22 of 25

Question:The upper half of an inclined plane of inclination q is perfectly smooth while the lower half is rough. A body starting from the rest at top comes back to rest at the bottom if the coefficient of friction for the lower half is given by

$$\mu$$ = sin $$\theta$$

$$\mu$$ = cot $$\theta$$

$$\mu$$ = 2 cos $$\theta$$

$$\mu$$= 2 tan $$\theta$$

Questions 23 of 25

Question:A body is sliding down an inclined plane having coefficient of friction 0.5. If the normal reaction is twice that of the resultant downward force along the incline, the angle between the inclined plane and the horizontal is [EAMCET (Engg.) 2000]

15$$^0$$

30 $$^0$$

45 $$^0$$

60 $$^0$$

Questions 24 of 25

Question:A body of mass 10 kg is lying on a rough plane inclined at an angle of 30$$^0$$ to the horizontal and the coefficient of friction is 0.5. the minimum force required to pull the body up the plane is

914 N

91.4 N

9.14 N

0.914 N

Questions 25 of 25

Question:A block of mass 1 kg slides down on a rough inclined plane of inclination 60$$^0$$ starting from its top. If the coefficient of kinetic friction is 0.5 and length of the plane is 1 m, then work done against friction is (Take g = 9.8 m/s$$^2$$)