CBSE Questions for Class 11 Engineering Physics Laws Of Motion Quiz 5 - MCQExams.com

A stone of mass $$1\;kg$$ is tied to the end of a string of $$1\;m$$ long. It is whirled in a vertical circle. If the velocity of the stone at the top be $$4\;m/s$$. What is the tension in the string?
  • $$\;6\;N$$
  • $$\;16\;N$$
  • $$\;5\;N$$
  • $$\;10\;N$$
Figures $$I, II, III\ and\ IV$$ depicts variation of force with time. In which situation impulse will be maximum?

281425_86d30fb9ba1e405e9e4b8911098920ec.png
  • $$I \&II$$
  • $$III \& I$$
  • $$III \& IV$$
  • $$Only\ IV$$
A particle of mass $$'m'$$ describes a circle of radius $$(r)$$. The centripetal acceleration of the particle is $$\displaystyle\frac{4}{r^2}$$. The momentum of the particle:
  • $$\;\displaystyle\frac{2m}{r}$$
  • $$\;\displaystyle\frac{2m}{\sqrt{r}}$$
  • $$\;\displaystyle\frac{4m}{r}$$
  • $$\;\displaystyle\frac{4m}{\sqrt{r}}$$
A mass tied to a string moves in a vertical circle with a uniform speed of $$5\;m/s$$ as shown. At the point $$P$$ the string breaks. The mass will reach a height above $$P$$ of nearly: $$(g=10\ m/s^{2})$$
281289_9e5aee9304574026bff2f5a8515de9e6.png
  • $$\;1\;m$$
  • $$\;0.5\;m$$
  • $$\;1.75\;m$$
  • $$\;1.25\;m$$
In a vertical circle of radius $$(r)$$, at what point in its path a particle may have tension equal to zero:
  • highest point
  • lowest point
  • at any point
  • at a point horizontal from the centre of radius
A stone attached to one end of a string is whirled in a vertical circle. The tension in the string is maximum when
  • the string is horizontal
  • the string is vertical with the stone at highest position
  • the string is vertical with the stone at the lowest position
  • the string makes an angle of $$45^{\circ}$$ with the vertical
A particle is moving in a vertical circle, the tension in the string when passing through two position at angle $$30^{\circ}$$ and $$60^{\circ}$$ from vertical from lowest position are $$T_1$$ and $$T_2$$ respectively, then 
  • $$T_1 = T_2$$
  • $$T_1 > T_2$$
  • $$T_1 < T_2$$
  • $$T_1\ge T_2$$
A pendulum bob has a speed $$3\;m/s$$ while passing through its lowest position, length of the pendulum is $$0.5\;m$$ then its speed when it makes an angle of $$60^{\circ}$$ with the vertical is
  • $$\;2\;m/s$$
  • $$\;1\;m/s$$
  • $$\;4\;m/s$$
  • $$\;3\;m/s$$
In the given figure a block of weight $$10 N$$ is resting on a horizontal surface. The coefficient of static friction between the block and the surface is $$\mu_s = 0.4$$. A force of $$3.5 N$$ will keep the block in uniform motion, once it has been set in motion. A horizontal force of $$3 N$$ is applied to the block, then the block will

282246_7768c93851604cd9a150f4752e5e9a53.png
  • move over the surface with constant velocity.
  • move having accelerated motion over the surface.
  • will not move.
  • first it will move with a constant velocity for some time and then it will have an accelerated motion.
A bob hangs from a rigid support by an inextensible string of length $$\ell$$. If it is displaced through a distance $$\ell$$ (from the lowest position) keeping the string straight, & then released. The speed of the bob at the lowest position is:
293402.png
  • $$\sqrt{g\ell}$$
  • $$\sqrt{3g\ell}$$
  • $$\sqrt{2g\ell}$$
  • $$\sqrt{5g\ell}$$
A metal block is resting on a rough wooden surface. A horizontal force applied to the block is increased uniformly. Which of the following curves correctly represents velocity of the block ?
A ball of mass 50 gm is dropped from a height h = 10 m. It rebounds losing 75 percent of its kinetic energy. If it remains in contact with the ground for At =0.01 sec, the impulse of the impact force is
(take 9 = 10 $$m/s^2$$)
  • 1.3 N - s
  • 1.06 N - s
  • 1300 N - s
  • 105 N - s
A block of mass $$2 kg$$ is placed on the floor. The coefficient of static friction is $$0.4$$. Force of $$2.8N$$ is applied on the block. The force of friction between the block and the floor is (Taken $$g = 10m/s^2$$)
  • 2.8 N
  • 8 N
  • 2.0 N
  • zero
A particle slides from rest from the topmost point of a vertical circle of radius ($$r$$) along a smooth chord making an angle $$(\theta)$$ with the vertical the time of decent is 
  • Least for $$\theta=0^{\circ}$$
  • Maximum for $$\theta=0^{\circ}$$
  • Least for $$\theta=45^{\circ}$$
  • Independent of $$\theta$$
A body of mass M is kept on a rough horizontal surface (friction coefficient =$$\mu$$ ). A person is trying to pull the body by applying a horizontal force but the body is not moving. The force by the surface on A is F where
  • $$F=Mg$$
  • $$F=\mu Mg$$
  • $$Mg\leq F\leq Mg\sqrt {1+\mu^2}$$
  • $$Mg\geq F\geq Mg\sqrt {1-\mu^2}$$
A rod of weight $$w$$ is supported by two parallel knife edges $$A$$ & $$B$$ and is in equilibrium in a horizontal position. The knives are at a distance $$d$$ from each other. The center of mass of the rod is at a distance $$x$$ from $$A.$$ The normal reactions at $$A$$ and $$B$$ will be
  • $$N_A \, =\, 2w (1\, -\, x/d),\, N_B\, =\, wx/d$$
  • $$N_A\, =\, w\, (1\, -\, x/d),\, N_B\, =\, wx/d$$
  • $$N_A\, =\, 2w(1\, -\, x/d), N_B\, =\, 2wx/d$$
  • $$N_A\, =\, w(2\, -\, x/d), N_B\, =\, wx/d$$
A hammer weighing 3 kg, moving with a velocity of 10 m/s, strikes against the head of a spike and drives it into a block of wood. If the hammer comes to rest in 0.025 s, the impulse associated with the spike will be :
  • 30 Ns
  • -30 Ns
  • 15 Ns
  • -15 Ns
A bead is free to slide down a smooth wire tightly stretched between points $$A$$ and $$B$$ on a verticle circle of radius $$R$$. If the bead starts from rest at '$$A$$', the highest point on the circle, its velocity when it arrives at $$B$$ is

298025.png
  • $$2\sqrt{gR}$$
  • $$2\sqrt{gR} \cos{\theta}$$
  • $$\displaystyle \dfrac{2\sqrt{R}}{g}$$
  • None of the above
Physical independence of force is a consequence of _____.
  • first law of motion
  • second law of motion
  • third law of motion
  • all ofthese laws
The change in momentum of a vehicle weighing 2000 kg when its speed increases from 36 km/h to 72 km/h uniformly is :
  • 15000 kg.m/s
  • 4000 kg.m/s
  • 20000 kg.m/s
  • 7200 kg.m/s
A stationary ball weighing 0.25 kg acquire a speed of $$10\:m/s$$ when hit by a hockey stick. The impulse imparted to the ball is:
  • $$0.25\:N\times s$$
  • $$2.5\:N\times s$$
  • $$2\:N\times s$$
  • $$0.5\:N\times s$$
A body of mass 'm' and velocity 'u' strikes a wall and rebounds with velocity 'v'. The change in momentum is:
  • $$m(v-u)$$
  • $$m(u-v)$$
  • $$-m(v+u)$$
  • none of these
A stationary ball weighing 0.25 kg acquires a speed of 10 m/s when hit by a hockey stick. The impulse imparted to the ball is :
  • 2.5 Ns
  • 2.0Ns
  • 1.5 Ns
  • 0.5Ns
A ball weighing $$10  g$$ hits a hard surface vertically with a speed of $$5  {m}/{sec}$$ and rebounds with the same speed. The ball remains in contact with the surface for $${1}/{100}  sec$$. The average force exerted by the surface on the ball is
  • $$100 N$$
  • $$10 N$$
  • $$1 N$$
  • $$0.1 N$$
A boat at rest has two persons of unequal weights seated at either end. If they walk across the boat and interchange their positions,
  • The boat will move in the direction of walking of the lighter person
  • The boat will move in the direction of walking of the heavier person
  • The boat will not move at all
  • The boat will oscillate about a mean position and stop once the persons have moved to the new positions
  • None of these
Two forces act on either side of rigid body of negligible mass suspended by string as shown in the figure. If R is the resultant force the tension of the string T = _____ gwt.
401161_a68d740cd8754787ac5356d5dce3c3d4.png
  • $$26$$
  • $$41$$
  • $$82$$
  • $$16$$
Every action has reaction. These action-reaction are 
  • Equal, opposite and acting on the same body
  • Equal, in the same direction and acting on same body
  • Equal, opposite and acting on different bodies
  • Equal, in same direction and acting on different bodies.
The effect of an impulse force on the body is measured only in terms of its
  • Force
  • Moment of momentum
  • Impulse
  • None of these
Friction is a/an
  • self-adjusting force
  • necessary evil
  • important force in daily life
  • all the above
A rubber of mass $$200$$ g hits a wall normally with a velocity of $$\displaystyle { 10\ ms }^{ -1 }$$  and bounces back with a velocity of $$\displaystyle { 8\ ms }^{ -1 }$$. The impulse is _____ Ns. 
  • $$-0.5$$
  • $$+0.5$$
  • $$-3.6$$
  • $$+3.6$$
If the momentum of a body is doubled, the kinetic energy is
  • Halved
  • Unchanged
  • Doubled
  • Becomes 4 times
A disc of mass 10 g is kept floating horizontally by throwing 10 marbles per second against it from below. The marbles strike the disc normally and rebound downwards with the same speed. If the mass of each marble is 5 g, the velocity with which the marbles are striking the disc is $$\displaystyle \left( g=9.8{ m }/{ { s }^{ 2 } } \right) $$
  • $$\displaystyle 0.98m/s$$
  • $$\displaystyle 9.8m/s$$
  • $$\displaystyle 1.96m/s$$
  • $$\displaystyle 19.6m/s$$
A ball is moving in a circular path of radius $$5m$$. If tangential acceleration at any instant is $$10\ m/s^2$$ and the net acceleration makes an angle $$30^o$$ with the centripetal acceleration, then the instantaneous speed is.
  • $$50\sqrt{3}m/s$$
  • $$9.3\ m/s$$
  • $$6.6\ m/s$$
  • $$5.4\ m/s$$
An aircraft executes a horizontal loop with a speed of $$150$$ m/s with its wings banked at an angle of $$\displaystyle { 12 }^{ o }$$. The radius of the loop is $$\displaystyle \left( g=10{ m }/{ { s }^{ 2 } } \right) $$
  • 10.6 km
  • 9.6 km
  • 7.4 km
  • 5.8 km
A stone ties to a rope is rotated in a vertical circle with uniform speed. If the difference between the maximum and minimum tension in the rope is $$20\  N$$, mass of the stone in $$kg$$ is:
 ($$\displaystyle g=10{ ms }^{ -2 }$$)
  • $$1.0$$
  • $$1.5$$
  • $$0.5$$
  • $$0.75$$
In vertical circular motion, the ratio of kinetic energy to potential energy at the horizontal position is ____________.
  • $$5:2$$
  • $$2:1$$
  • $$3:2$$
  • $$2:3$$
A stone tied to a string is rotated in a vertical plane. If mass of the stone is $$m$$, the length of the string is $$r$$ and the linear speed of the stone is $$v$$,When the stone is at its lowest point, then the tension in the string will be :
  • $$\displaystyle \frac { m{ v }^{ 2 } }{ r } +mg$$
  • $$\displaystyle \frac { m{ v }^{ 2 } }{ r } -mg$$
  • $$\displaystyle \frac { mv }{ r } $$
  • $$\displaystyle mg$$
If the string were to break at point II, what would be the path of the ball?
485593_b6c13b64e3094f35845dd994f15ac3dc.png
  • None of these
A $$50 kg$$ acrobat is swinging on a rope with a length of $$15 m$$ from one horizontal platform to another. Both platforms are at equal height.
If the maximum tension the rope can support is $$1200 N$$, which of the following answer best represents the maximum velocity the acrobat can reach without breaking the rope?
  • $$25 {m}/{s}$$
  • $$19 {m}/{s}$$
  • $$20 {m}/{s}$$
  • $$15 {m}/{s}$$
  • $$5 {m}/{s}$$
Which of the following statements is true?
485590_be3171b356084855bdbe0f0c72be3059.png
  • The tension in the string is greater at points III than at point I
  • The tension in the string is greater at points I than at point III
  • The tension at point I is equal to the tension at point III
  • The tension in the string is greatest at point II
  • The tension in the string is same at points I, II and III
A ball of mass $$m$$ is attached with the string of length $$R$$, rotating in circular motion, with instantaneous velocity $$v$$ and centripetal acceleration $$a$$.
Calculate the centripetal acceleration of the ball if the length of the string is doubled?
  • $${a}/{4}$$
  • $${a}/{2}$$
  • $$a$$
  • $$2a$$
  • $$4a$$
A uniform rod of mass 1 kg is hanging from a thread attached at the midpoint of the rod. A block of mass $$m$$=3kg hangs at the left end of the rod and block of mass $$M$$ hangs at the right side at 80 cm from block $$m$$. If system is in equilibrium. Calculate $$M$$.

480165_a722630effbe44769ecb73c9ddbf2120.png
  • 4 kg
  • 5 kg
  • 6 kg
  • 8 kg
  • 9 kg
The given rod is uniform and has a mass m. Find the tension in the string.
480278.jpg
  • $$\dfrac { \left( mg\sin { \theta } \right) }{ 2 } $$
  • $$\dfrac { mg\sin { } }{ 2 } $$
  • $$\dfrac { \left( mg\cos { \theta } \right) }{ 2 } $$
  • $$\dfrac { mg }{ 2 } $$
  • $$mg$$
A $$110 kg$$ panda is riding on a $$3.0 m$$ long swing whose mass can be considered negligible. The highest point of its arc occurs when the swing makes a $${20}^{o}$$ angle with the vertical.
What is the magnitude of the total tension in the ropes of the swing at that point?
495418.jpg
  • $$0N$$
  • $$103 N$$
  • $$369 N$$
  • $$1013 N$$
  • $$1078 N$$
A uniform bar is lying on a flat horizontal table. The bar is acted upon by $${F}_{1}$$ and $${F}_{2}$$,besides the gravitational and normal forces (which cancel),   $${F}_{1}$$ and $${F}_{2}$$ are parallel to the surface of the table. If the net force on the rod is zero, then which one of the following statement is true?
  • The net torque on the bar must also be zero
  • The bar can accelerate translationally if $${F}_{1}$$ and $${F}_{2}$$ are not applied at the same point
  • The net torque will be zero if $${F}_{1}$$ and $${F}_{2}$$ are applied at the same point
  • The bar cannot accelerate translationally or rotationally
  • None of the above
Two objects rest on a seesaw. The first object has a mass of 3 kg and rests 10 m from the pivot. The other rests 1 m from the pivot. What is the mass of the second object if the seesaw is in equilibrium? 
491581_aa9b435a7caf43aa869b842507ec400f.png
  • 0.3 kg
  • 3 kg
  • 10 kg
  • 30 kg
  • 50 kg
The catcher prepares to receive a pitch from the pitcher. As the ball reaches and makes contact with his glove, the catcher pulls his hand backward. This action reduces the impact of the ball on the catcher's hand because:
  • The energy absorbed by his hand is reduced
  • The momentum of the pitch is reduced
  • The time of impact is increased
  • The time of impact is reduced
  • The force exerted on his hand remains the same
A person is moving on a rough horizontal surface towards east. Then the direction of friction force is towards
  • west
  • east
  • north
  • cant say depends on the situation.
A plane travelling at $$300 {m}/{s}$$ banks its wings to enter into a horizontal circular turn. The circular path has a radius of $$2.7 km$$.
Which of these values best represents the angle of the wings relative to the horizontal if the plane experiences no change in its altitude during the turn?
  • $${8}^{o}$$
  • $${16}^{o}$$
  • $${20}^{o}$$
  • $${25}^{o}$$
  • $${32}^{o}$$
A ball of mass 100 g is moving with a velocity of 10 m $$s^{-1}$$. The force of the blow by the bat acts for 0.01 seconds. What is the force exerted on the ball by the bat if the ball retraces its path with same speed?
  • 100 N
  • 200 N
  • 300 N
  • 400 N
0:0:1


Answered Not Answered Not Visited Correct : 0 Incorrect : 0

Practice Class 11 Engineering Physics Quiz Questions and Answers