Physics

Friction and Inclined Planes

63 Questions

Friction and inclined plane problems focus on calculating forces, coefficients of static and kinetic friction, and motion on rough surfaces. Questions cover blocks on horizontal tables, angled planes, and simple harmonic motion systems. These physics concepts are strictly evaluated in engineering entrance and civil services tests.

Static friction coefficientKinetic friction forceInclined plane blocksDamped vibrations systemHorizontal table motion

Friction and Inclined Planes Questions

Multiple choice physics heat energy transfers heat energy heat, internal energy and work internal energy

A block of mass $100\ g$ slides on a rough horizontal surface. If the speed of the block decreases from $10\ m/s^{-1}$ to $5\ m/s^{-1}$, the thermal energy developed in the process is:

  1. $3.75\ J$
  2. $37.5\ J$
  3. $0.375\ J$
  4. $0.75\ J$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Given:
The mass of the block is $100\ g$
The initial speed of the block is $10\ m/s$
The final speed of the block is $5\ m/s$

The thermal energy developed in the process is due to the lowering of the speed i.e. the reduction in the kinetic energy of the block.

Thermal energy = loss in kinetic energy
$=\dfrac{1}{2}m(v^2 _1-v^2 _2)$

$=\dfrac{1}{2}100\times 10^{-3}(10^2-5^2)$

$=3.75J$
Multiple choice physics free, damped and forced oscillations forced vibration forced vibrations free, forced and damped oscillations

A highly rigid cubical block A of small mass M and side L is fixed rigidly on another cubical block B of the same dimensions and of low modulus of rigidity $\eta $ such that the lower face of A completely covers the upper face of B.  The lower face of B is rigidly held on horizontal surface.  A small force is applied perpendicular to the side faces of A.  After the force is withdrawn, block A executes small oscillations the time period of which is given by 

  1. $2\pi \sqrt{M\eta L}$
  2. $2\pi \sqrt{\frac{M-\eta }{L}}$
  3. $2\pi \sqrt{\frac{M-L}{\eta }}$
  4. $2\pi \sqrt{\frac{M-N}{\eta L}}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Multiple choice physics friction advantages and disadvantages of friction merits and demerits of friction and methods to reduce it friction: a necessary evil

_______ helps in writing with a pen or pencil on a paper.

  1. Magnetic force

  2. Electric charge

  3. Chemical force

  4. Frictional force
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The irregularities between the paper and the pen or pencil create friction. Due to friction, the particles of ink or lead stick to the paper and get locked in its irregularities. If there would be no friction between the paper and pen or pencil, the ink/lead would not stick to the paper and we would not be able to write.

Multiple choice power work and power work, energy and power physics energy and its forms

A rectangular block of dimensions $6m\times 4m\times 2m$ and of density $1.5\ gm/c.c$ is lying on horizontal ground with the face of large area in contact with the ground. The work done in arranging it which its smallest area in contact with a ground is, $(g=10ms^{-1})$

  1. $2880\ kJ$
  2. $1440\ kJ$
  3. $3800\ kJ$
  4. $720\ kJ$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

m=v*density

m=$6\times 4\times 2\times 1.5\times 10^3=72\times 10^3$kg
when face with large area is in contact with the ground its height is 2m
Centre of mass is at a height of 1m

when face with small area is in contact with the ground its height is 6m
Centre of mass is at a height of 3m
W=$72\times 10^4(3-1)=1440 kJ$

Multiple choice power work and power work, energy and power physics energy and its forms

A small body of mass $m$ is located on a horizontal plane. The body acquires a horizontal velocity ${v} _{0}$. Find mean power developed by the frictional force, during the whole time of its motion. Coefficient of friction is $\mu$

  1. $\cfrac { -\mu mg{ v } _{ 0 } }{ 3 } $
  2. $\cfrac { -\mu mg{ v } _{ 0 } }{ 2 } $
  3. $\cfrac { -\mu mg{ v } _{ 0 } }{ 5 } $
  4. $\cfrac { -\mu mg{ v } _{ 0 } }{ 6 } $
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The body decelerates due to friction: a = -mu * g. Final velocity is 0. Time taken t = v0 / (mu * g). Displacement s = v0^2 / (2 * mu * g). Work done = -mu * m * g * s = -m * v0^2 / 2. Mean power = Work / t = (-m * v0^2 / 2) / (v0 / mu * g) = -mu * m * g * v0 / 2.

Multiple choice horizontal oscillations of a mass attached to a spring oscillations due to a spring simple harmonic motion oscillations physics

Two blocks m and m each of mass 3kg is connected with spring of constant 50 N/m. The coefficient of friction between m and ground is 0.4. The maximum amplitude of m during its oscillation, so that m does not move, is 

  1. 24 cm

  2. 12 cm

  3. 2.4 cm

  4. 6 cm
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

For the block not to move, the maximum spring force must be less than or equal to the limiting friction. k*A <= mu*m*g. 50 * A <= 0.4 * 3 * 10. 50 * A <= 12. A <= 12/50 = 0.24 m = 24 cm.

Multiple choice physics newton's laws of motion weightlessness application of newton's law of motion escape velocity

The backside of a truck is open and a box of 40kg is placed 5m away from the rear end.The coefficient of friction of the box with the surface of the truck is 0.15.The truck starts from rest with $2m/s^2$ acceleration.Calculate the distance covered by the truck when the box falls off

  1. 20m

  2. 30m

  3. 40m

  4. 50m
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The box experiences a pseudo-force F = m*a = 40 * 2 = 80N. The friction force is f = mu * m * g = 0.15 * 40 * 10 = 60N. The net force on the box is F_net = F - f = 80 - 60 = 20N. Acceleration of the box relative to the truck is a_rel = F_net / m = 20 / 40 = 0.5 m/s^2. Time to fall off: s = 0.5 * a_rel * t^2 => 5 = 0.5 * 0.5 * t^2 => 5 = 0.25 * t^2 => t^2 = 20 => t = sqrt(20). Distance covered by truck: S = 0.5 * a_truck * t^2 = 0.5 * 2 * 20 = 20m.

Multiple choice physics turning effects of forces centre of gravity forces - vectors and moments acceleration due to gravity

A book is lying on a table, what is the angle between the book on the table and the weight of the book?

  1. $0^o$
  2. $45^o$
  3. $90^o$
  4. $180^o$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Weight always point towards the center of the earth that is perpendicular to the surface of the earth that is towards the table and $perpendicular$ to surface of the table.


Now as the book is lying on the table i.e. book is $parallel$ to the table and the weight is perpendicular to the table so the required angle is $90^0$
Option C is correct.

Multiple choice physics force and newton's laws of motion first law of motion newton's first law of motion momentum and newton's laws

A block is moved from rest through a distance of 4m along a straight line path.The mass of the block is 5 kg,and the  force acting on it is 20 N.If the kinetic energy acquired by the block be 40J,at what angle to the path the force is acting:

  1. $30^o$
  2. $60^o$
  3. $45^o$

  4. none of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
From work Energy theorem 
$ \triangle w = \triangle KE $ 
$ F.S = K.E $
$ F.S cos\theta = KE  $
$ cos\theta = \frac{KE}{FS} $
$ cos\theta = 1/2 $
$ \theta = 60^{\circ} $ 
Multiple choice physics along with motion what forces can do? force and it's unit force and its effects

An iron block of sides $50 cm\times 8 cm\times 15 cm$ has to be pushed along the floor. The force required will be minimum when the surface in contact with ground is

  1. $8 cm\times 15 cm $surface
  2. $50 cm\times 15 cm $surface
  3. $8 cm\times 50 cm $surface

  4. Force is same for all surfaces.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Force will be same for all the surfaces.
Hence, the correct option is $(D)$

Multiple choice physics simple machine common machines terms related to machines introduction to simple machines

The mechanical advantage of inclined plane of angle of inclination $60^{\circ}$ is equal to :

  1. $\dfrac{2}{\sqrt{3}}$
  2. $cosec 30^o$

  3. both (1) and (2)

  4. none of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Mechanical advantage of an inclined plane at an angle $\theta$ is  $ \dfrac{Length }{height}$$ = \dfrac{l}{h} = \dfrac{1}{sin \theta}$


$ = cosec \theta = cosec 60^o = \dfrac{1}{sin 60^o} = \dfrac{2}{\sqrt{3}}$

Multiple choice chemistry substances in the surroundings - their states and properties measurement of density properties of substances fundamental and derived units

A rectangular block 5m x 4m x 2m lies on a table with its largest surface in contact with the table. The work done to keep it so that the block rests on the smallest surface is, if its density is 600 k $m ^ { - 3 }$

  1. $352800 \mathrm { J }$

  2. zero
  3. $376000 \mathrm { J }$
  4. $24,0000 \mathrm { J }$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The volume of Rectangular block $ = 5m \times 4m \times 2m$

$ = 40\,\,{m^3}$
Mass = Volume $ \times$ Density
$\begin{array}{l} =40\, \, { m^{ 3 } }\times 600\, \, k{ m^{ -3 } } \ =24,000=2.4\times { 10^{ 4 } }\, \, hg \end{array}$
Potential energy of block when it is lying on its largest surface $= mgh$
$ = 2.4 \times {10^4} \times 9.8 \times 1\,\,joule$
Potential energy of the block when it is lying on 
$ = mgh = 2.4 \times {10^4} \times 9.8 \times 2.5$
Work done = difference in potential energy
$\begin{array}{l} =\left( { 2.4\times { { 10 }^{ 4 } }\times 9.8\times 2.5-2.4\times { { 10 }^{ 4 } }\times 9.8\times 1 } \right) joule \ =2.4\times { 10^{ 4 } }\times 9.8\times 1.5\, \, joule \ =352800\, \, joule \end{array}$
Option A

Multiple choice

The coefficient of friction is a dimensionless quantity that represents the ratio of the force of friction to the normal force between two surfaces.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The coefficient of friction is a property of the materials in contact and is independent of the area of contact.

Multiple choice

In a physics-based puzzle game, a player character pushes a crate with a mass of 50 kg across a horizontal surface with a coefficient of kinetic friction of 0.2. If the player applies a force of 100 N to the crate, what is the acceleration of the crate?

  1. 1.6 m/s^2

  2. 2.4 m/s^2

  3. 3.2 m/s^2

  4. 4.0 m/s^2
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The force of kinetic friction (F_k) is given by the equation: F_k = μ_k * N, where μ_k is the coefficient of kinetic friction and N is the normal force. Since the crate is on a horizontal surface, the normal force is equal to the weight of the crate: N = m * g, where m is the mass and g is the acceleration due to gravity. Plugging in the values, we get: F_k = 0.2 * 50 kg * 9.8 m/s^2 = 98 N. The net force acting on the crate is the force applied by the player minus the force of kinetic friction: F_net = 100 N - 98 N = 2 N. Using Newton's second law: F = m * a, where F is the net force, m is the mass, and a is the acceleration, we can calculate the acceleration of the crate: a = F_net / m = 2 N / 50 kg = 1.6 m/s^2.