CBSE Questions for Class 11 Medical Physics Work, Energy And Power Quiz 9 - MCQExams.com

A $$4\ kg$$ particle moves along the $$X-$$axis. Its position $$x$$ varies with time according to $$x\left( t \right) = t + 2{t^3}$$ , where $$X$$ is in $$m$$ and $$t$$ is in seconds. Compute kinetic energy of the particle in time t
  • $$ KE=72t^2+24t+2$$
  • 0
  • 20t
  • 40t
A particle of mass m strikes a wall at an a wall at angle of incidence $$60^o$$ with velocity v elastically. The change in momentum is:
  • $$mv$$
  • $$m v/2$$
  • $$-2 m v$$
  • $$Zero$$
A ball is dropped from certain height, after striking the gourn it rebounds till $$\frac{2}{5}th$$ of the initial height. The ration of its speed just before and just after striking the ground is [assume no loss of energy due to air friction]
  • $$\sqrt{\dfrac{2}{5}}$$
  • $$\dfrac{2}{5}$$
  • $$\sqrt{\dfrac{5}{2}}$$
  • $$\dfrac{5}{2}$$
A horizontal $$50\ N$$ force acts on a $$2\ kg$$ crate which is at rest on a smooth horizontal surface. At the instant the particle has gone $$2\ m$$, the rate at which the force is doing work is
  • $$2.5\ W$$
  • $$25\ W$$
  • $$100\ W$$
  • $$500\ W$$
When water falls from a height, the energy changes from,
  • kinetic to potential
  • potential to kinetic
  • chemical to mechanical
  • Mechanical to chemical
A particle of mass $$4m$$ which is at rest explodes into masses $$m,m$$ & $$2m$$. Two of the fragments of masses $$m$$ and $$2m$$ are found to move with equal speeds $$v$$ each in opposite directions. The total mechanical energy released in the process of explosion is
  • $$m{v}^{2}$$
  • $$2m{v}^{2}$$
  • $$\dfrac{1}{2}m{v}^{2}$$
  • $$4m{v}^{2}$$
A particle is projected on friction less inclined plane of inclination $$90^{\circ}$$ from the horizontal, with the projection angle $$45^{\circ}$$ from the inclined plane as shown in the figure. After one collision from the plane. It reaches to its initial point of projection. Coefficient of restitution between particle and plane is
  • $$\frac{2}{3}$$
  • $$\frac{1}{3}$$
  • $$\frac{3}{25}$$
  • $$\frac{1}{\sqrt{2}}$$
If two balls each of mass 0.06 Kg moving in opposite directions with speed 4 m/sec collides and rebound with the same speed,then coefficient of restitution for the collision will be:-
  • $$ \frac { 1 }{ 4 } $$
  • $$\frac { 1 }{ 2} $$
  • 1
  • 0
A particle moves along the x- axis from x=0 to x=5 m under the influence of a force given by $$F=7-2x+3x^2$$.Work done in the process is 
  • 70
  • 270
  • 35
  • 135
A gun fires a shell of mass $$1.5 $$kg with velocity of $$150$$ m/s and recoils with a velocity of $$2.5$$ m/s. 
Calculate the mass of the gun.
  • $$20$$ kg
  • $$30$$ kg
  • $$90$$ kg
  • $$60$$ kg
At the instant t= 0 a force F=kt( k is a constant) acts on a small body of mass m resting on a smooth horizontal surface.The time,when body leaves the surface is:
  • $$mg\ k \ sin \alpha $$
  • $$\dfrac{k }{mg \ sin \alpha}$$
  • $$\dfrac{mg \ sin \alpha}{k }$$
  • $$\dfrac{mg}{k \ sin \alpha}$$
A time dependent force F = 6t acts on a particle of mass 1 kg. If the particle starts from set, the work done by the force during the first 1 sec. will be :
  • 22 J
  • 9 J
  • 18 J
  • 4.5 J
Identify the wrong statement
  • A body can have momentum without energy
  • A body can have energy without momentum
  • the momentum is conserved in an elastic collision
  • Kinetic energy is not conserved in an inelastic collision
Two identical spheres move in opposite direction with speed $$v_1$$ and $$v_2$$ and pass behind an opaque screen, where they may either cross without touching ( Event 1) or make an elastic head-on collision ( Event 2)
  • We can never make out which events has occured
  • We cannot make out which event has occured only if $$v_1= v_2$$
  • We can always make out which event has occured
  • We can make out which event has occured only if $$v_1= v_2$$
A ball of mass m approaches a wall of mass M (>> m) with the speed 4 m/s along normal to the wall. The speed of wall is 1m/s towards the ball . The speed of the ball after an elastic collision with the wall is-
  • 5 m/s away from the wall
  • 3 m/s away from the wall
  • 9 m/s away from the wall
  • 6 m/s away from the wall
A ball falls from a height such that it strikes the floor of lift at $$10\ m/s$$, if lift is moving in the upward direction with a velocity $$1\ m/s$$ , then velocity with the ball rebounds after elastic collision will be then
  • $$11\ m/s$$
  • $$12\ m/s$$
  • $$13\ m/s$$
  • $$9\ m/s$$
The $$P.E.$$ and $$K.E.$$ of a helicopter flying horizontally at a height $$400\ m$$ are in the ratio $$5:2$$. The velocity of the helicopter is:
  • $$56\ m/s$$
  • $$28\ m/s$$
  • $$14\ m/s$$
  • $$42\ m/s$$
A particle is acted upon by a force F which varies with position x as shown in the figure. If the particle at $$x=0$$ has the kinetic energy of $$25$$ J, then the kinetic energy of the particle at $$x=16$$m is?
1208470_a40f7e31514246c2ad656b86645125c1.png
  • $$45$$J
  • $$30$$J
  • $$70$$J
  • $$135$$J
The work done by a force $$\vec{F}=\left ( -6x^3\hat{i} \right )\ N$$ is displacing a particle from $$x=4\ m$$ to $$x=-2\ m$$ is

  • $$-240\ J$$
  • $$360\ J$$
  • $$120\ J$$
  • $$420\ J$$
Velocity-time graph of a particle of mass $$2\,\,kg$$ moving in a straight line as shown in figure. Work done by all the forces on the particle is :
1206603_ac526021192a4099a07c75ae23d91baa.png
  • $$400\,J$$
  • $$- 400\,J$$
  • $$- 200\,J$$
  • $$200\,J$$
A body of mass $$6\,kg$$  is under a force which causes displacement in it given by $$S = \dfrac{{{t^2}}}{4}$$  metres where $$t$$ is time. The work done by the force in $$2$$ seconds is:-
  • $$12\,J$$
  • $$9\,J$$
  • $$6\,J$$
  • $$3\,J$$
A light particle moving horizontally with a speed of $$12\ m/s$$ strikes a very heavy block moving in the same direction at $$10\ m/s$$. The collision is one-dimensional and elastic. If the speed of the block does not change after the collision, the particle will
1209463_0a3c7af683594f95823cca5c0be037db.png
  • Move at $$2\ m/s$$ in its original direction
  • Move at $$8\ m/s$$ in its original direction
  • Move at $$8\ m/s$$ opposite to its original direction
  • Move at $$12\ m/s$$ opposite to its original direction
Potential energy of a particle is given as $$U(x)=2{x}^{3}-9{x}^{2}+12x$$ where $$U$$ is in joule and $$x$$ is in metre. If the motion of a particle is S.H.M then find the approx. potential energy of the particle is:
  • $$-36J$$
  • $$4J$$
  • $$5J$$
  • None of these
Find the reading of machine. Given each box of mass$$=15 kg$$,mass of man $$ 1=30kg$$, mass of man $$2=40 kg$$ and of each weighing machine $$=5 kg$$
1190764_47b1e62228974051a1e4cd887bbca763.PNG
  • $$360/11 kg, 400/11 kg $$
  • $$330/11 kg, 440/11 kg $$
  • $$360/11 kg, 440/11 kg $$
  • $$350/11 kg, 240/11 kg $$
When a massive body suffers an elastic collision with a stationary light body, then massive body approximately comes to rest and light body- 
  • acquires velocity greater than initial velocity of massive body
  • sticks to the massive body and remains at rest.
  • acquires half the initial velocity of the massive body
  • remains at rest but does not stick to the massive body.
When a conservation force does positive work on a body then 
  • its potential energy must increase
  • its potential energy must decrease
  • its kinetic energy must increase
  • its total energy must decrease
Five equal force of $$10$$N each applied at one point and all are lying in one plane. If the angles between them are equal, the resultant force will be
  • zero
  • $$10$$N
  • $$20$$N
  • $$10\sqrt2$$
A body is moving along y-axis and force acting on it is given by F = sin Ky, where K is a constant . The work done by the force from y = 0 to y = 1 is 
  • $$\dfrac { 1 }{ K(1-sinK) } $$
  • $$\dfrac { { 2sin }^{ 2 }\dfrac { K }{ 2 } }{ K } $$
  • $$\dfrac { cosK-1 }{ K } $$
  • cos K - 1
A force $$F = -kx^3$$ is acting on a block moving along x-axis. Here, k is a positive constant. Work done by this force is:
  • positive in displacing from x = 3 to x = 1
  • positive in displacing from x = -1 to x = 3
  • negative in displacing from x = 3 to x = 1
  • negative in displacing from x = -1 to x = 3
A body of mass 'M' collides against a wall with a velocity v and retraces its path with the same speed. the change in momentum is ............. (take initial direction of velocity as positive)
  • Zero
  • 2Mv
  • Mv
  • -2 Mv
A force $$F=Kx^{2}$$ acts on a particle at angle of $$60^{o}$$ with $$x-$$ axis. The work done in displacing the particle from $$x_{1}$$ to $$x_{2}$$ will be:
  • $$\dfrac{kx^{2}}{2}$$
  • $$\dfrac{k}{6}(x_{3}^{2}-x_{1}^{3})$$
  • $$\dfrac{k}{2}(x_{2}^{3}-x_{1}^{3})$$
  • $$\dfrac{k}{3}(x_{2}^{3}-x_{1}^{3})$$
Gravel is dropped on a conveyor belt at the rate of $$2kg/s$$. The extra force required to keep the belt moving at $$3 ms^{-1}$$ is
  • $$1 N$$
  • $$3 N$$
  • $$4N$$
  • $$6 N$$
A car is travelling at 5 m/s up a gradient of 1 inThe car weight 6 tonnes and the friction is 48 kg wt. The work done per second in maintaining the motion of car up the gradient is $$(g=10ms^{-2}$$)
  • 12400 W
  • 1362 W
  • 17400 W
  • 1520 W
A force acts on a $$20g$$ particle in such a way that the position of the particle as a function of time is given by $$x=3t-4t^2+t^3$$, where x is in meters and $$t$$ is in seconds. The work done during the  first $$4sec$$ is:
  • $$-1.6J$$
  • $$-1600J$$
  • $$2.6 J$$
  • $$1600J$$
If a resultant force of $$30N$$ acts on a body of mass $$6kg$$.What is the acceleration of the body?
  • $$20m/sec^2$$
  • $$12m/sec^2$$
  • $$5m/sec^2$$
  • $$8m/sec^2$$
A body of mass 2.0 kg makes an elastic collision with another body at rest and continues to move in the original direction but with one-fourth of its original speed v. What is the mass of other body and the speed of the center of mass of two bodies ?
  • $$ 1.0 kg and \frac {2}{3}v $$
  • $$ 1.2 kg and \frac{5}{8} $$
  • $$ 1.4 kg and \frac {10}{17} v $$
  • $$ 1.5 kg and \frac {4}{7} v $$
 Work done in lifting a body is calculated by
  • Mass of the body $$ \times $$ vertical distance moved
  • Force acting on a body $$ \times $$ vertical distance moved
  • Weight acting on the body $$ \times $$ vertical distance moved
  • None of the above.
When linear momentum of a body becomes $$n$$ times, for the same applied stopping force, its stopping distance becomes 
  • $$n$$ times
  • $$\dfrac{1}{n}$$ times
  • $$n^{2}$$ times
  • $$\dfrac{1}{n^{2}}$$ times
A force is acting on a particle varies with the displacement x as $$F=ax-bx^2$$. Where a=1 N/m and $$b=1 N/m^2$$. The work done by this force for the first one meter (F is in newtons, x is in meters) is :
  • $$\dfrac{1}{6}J$$
  • $$\dfrac{2}{6}J$$
  • $$\dfrac{3}{6}J$$
  • None of these
A force $$F_1$$ on a body of 2 kg produces an acceleration of $$2.5 m/m^2$$ and other force $$F_2$$ acting on another body of mass 5 kg produces an acceleration of $$2 m/s^2$$. The ratio of $$F_2/F_1$$ is
  • $$2$$
  • $$4$$
  • $$6$$
  • $$8$$
A body of mass $$5 kg$$ under a force which causes displacement in it given $$S=\dfrac{t^2}{4}$$ meter where $$'t'$$ is time. The work done by the force in $$4 seconds$$ is:
  • $$12J$$
  • $$20 J$$
  • $$2.55 J$$
  • $$10 J$$
When the mass of body is halved and velocity is doubled, then the kinetic energy of the body 
  • remains same
  • is doubled
  • is 4 times
  • is $$\frac{1}{4}$$ th
A force $$F=Ay^{2}+By+C$$ acts on a body in the $$y$$ direction, The work done by this force during a displacement from $$y=-a$$ to $$y=a$$ is
  • $$\dfrac{2Aa^{2}}{3}$$
  • $$\dfrac{2Aa^{2}}{3}+2Ca$$
  • $$\dfrac{2Aa^{2}}{3}+\dfrac{Ba^{2}}{2}+Ca$$
  • $$None\ of\ these$$
A body of mass 0.5 kg travels in a straight line with velocity $$v=ax^{3/2}$$ where $$a=5m^{-1/2}s^{-1}$$. the work done by the net force during its displacement from $$x=0$$ to $$x=2m$$ is  
  • $$1.5J$$
  • $$50J$$
  • $$10J$$
  • $$100J$$
A body of mass $$15\ kg$$ moving with a velocity of $$10\ ms^{-1}$$ is bought to rest. The work done by the brake is
  • $$-250\ J$$
  • $$-500\ J$$
  • $$-750\ J$$
  • $$-1000\ J$$
A ball of mass $$5$$ kg experiences a force $$F=2x^{2}+x$$. Work done in displacing the ball by $$2$$ m is 
  • $$22/3$$ J
  • $$44/3$$ J
  • $$32/3$$ J
  • $$16/3$$ J
A force of $$F = 2x\hat{i} + 2\hat{j} + 3z^{2}\hat{k} N$$ is acting on a particle. Find the work done by this force in displacing the body from (1,2,3) into (3,6,1) m.
  • $$-10 J$$
  • $$100$$
  • $$10 J$$
  • $$1 J$$
Two wires of the same diameter of the same material having the length $$\ell$$ and $$2\ell$$. If the force is applied on each, the ratio of the work done in the two will be
  • $$1: 2$$
  • $$1: 4$$
  • $$2: 1$$
  • $$1: 1$$
By applying a force $$F=(3xy-5z) j +4zk$$ a particle is moved along the path $$y=x^2$$ from point $$(0,0,0)$$ to the point $$(2,4,0)$$. The work done by the F on the particle is (all values are in SI units)
1270771_88cb9d01112c47d38e7adb03c6428eff.png
  • $$\dfrac { 280 }{ 5 } J$$
  • $$\dfrac { 140 }{ 5 } J$$
  • $$\dfrac { 232 }{ 5 } J$$
  • $$\dfrac { 192 }{ 5 } J$$
Two masses $$10 \ gm$$ and $$40 \ gm$$ are moving with kinetic energies in the ratio $$9:25$$. The ratio of their linear momentum is:
  • $$5:6$$
  • $$3:10$$
  • $$6:5$$
  • $$10:3$$
0:0:1


Answered Not Answered Not Visited Correct : 0 Incorrect : 0

Practice Class 11 Medical Physics Quiz Questions and Answers