CBSE Questions for Class 11 Medical Physics Work, Energy And Power Quiz 10 - MCQExams.com

A particle of mass 1 kg is projected under gravity at an angle $${ 37 }^{ o }$$ with horizontal with 50 m/s. Instantaneous power delivered by gravity at t=1s is $$\left( sin{ 37 }^{ o }=\frac { 3 }{ 5 } ,cos{ 37 }^{ o }=\frac { 4 }{ 5 }  \right) $$
  • 200 J/s
  • -200 J/s
  • Zero
  • -400 J/s
A blocks is moved from rest through a distance of $$4m$$ along a straight line path. The mass of the blocks is $$5kg$$ and the force acting on it is $$20N$$. If the kinetic energy acquired by the block be $$40J$$, at what angle to the path the force is acting-
  • $${30}^{o}$$
  • $${60}^{o}$$
  • $${45}^{o}$$
  • none of the above
Mass of $$B$$ is four times that of $$A . B$$ moves with a velocity half that of $$A$$. Then, $$B$$ has 
  • kinetic energy equal to that of $$A$$
  • half the kinetic energy of $$A$$
  • twice the kinetic energy of $$A$$
  • kinetic energy one-fourth of $$A$$
The work done in placing a charge of 8$$\times $$$${ 10 }^{ -18 }$$ coulomb on a condenser of capacity 100 micro-farad is 
  • 16$$\times { 10 }^{ -32 }$$ joule
  • 3.2$$\times { 10 }^{ -26 }$$ joule
  • 4$$\times { 10 }^{ -10 }$$ joule
  • 32$$\times { 10 }^{ -32 }$$ joule
A body of mass 1 kg begins to move under the action of a time dependent  force $$ \overrightarrow { F } =(2t\hat { i } +3t^{ 2 }\hat { j } ) $$ N, where $$ \hat { i } $$ and $$ \hat { j }  $$ are unit vectors along x and y axes. What power will be developed by the force at the time t?
  • $$ (2t^2+3t^2)W $$
  • $$ (2t^4+4t^4)W $$
  • $$ (2t^3+3t^4)W $$
  • $$ (2t^3+3t^5)W $$
A wooden plank of length $$L$$, reacts on a frictionless floor. A boy of mass $$M$$ now runs over the plank starting from its one end. If mass of wooden plank is $$M/5$$, the distance covered by the boy relative to the ground will be:
  • $$L/6$$
  • $$5L/6$$
  • $$L/5$$
  • $$4L/5$$
A block of mass 10 kg is moving up on an inclined plane with constant acceleration 2 m/sec by applying a constant force F as shown in the fig. The work done on the block by applied force F in 2 s is
1392596_8ea8b2aa4e354531ac6c0508ebcbd0e6.png
  • 480
  • 240
  • 960
  • none
$$\overrightarrow { F }  =x\hat i+y\hat j$$, is this force:
  • a non conservation
  • a conservation force
  • depends upon X
  • depends upon $$y \quad \& \quad x$$
 A force of $$1200 \mathrm { N }$$ acting on a stone by means of a rope slides the stone through a distance{ of$$ 10 \mathrm { m }$$in a direction inclined at $$ 60 ^ { \circ } $$ force. The work done by the force is
  • $$6000 \sqrt { 3 } J$$
  • 6000 J
  • 12000 J
  • 8000 J
$$\begin{array} { l } { \text { A man weighing } 80 \mathrm { kg } \text { climbs a staircase } } \\ { \text { carrying a } 20 \mathrm { kg } \text { load. The staircase has } 40 } \\ { \text { steps, each of } 25 \mathrm { cm } \text { height. If he takes } 20 } \\ { \text { seconds to climb, the work done is } } \end{array}$$
  • $$9800 \mathrm { J }$$
  • $$245 \mathrm { J }$$
  • $$98 \times 10 ^ { 4 } J$$
  • 7840 J
A variable force given by $$ F= ( 3x^2 \hat i + 4 \hat j) $$ acts on a particle. the force is in newton and x is in meter. what is the change in KE of particle as it moves from point (2, 3) to (3, 0) 
  • -7J
  • zero
  • 7J
  • 19J
A particle moves along positive X-axis from x=$$0$$ to x=$$5$$ under influence of force is given by$$F={ x }^{ 2 }-2x-8.$$ The work done by the force is 
  • -69 units
  • -23.33 units
  • -5 units
  • zero
The displacement (x) and time (t) for a particle are related as $$t=\sqrt { x } +3$$. What is the work done in the first six second of its motion?
  • 3 J
  • 4 J
  • Zero
  • 5 J
Five identical balls each of mass m and radius r are strung like beads at random and at rest along a smooth, rigid horizontal thin rod of length L, mounted between immovable supports. Assume $$10r<L$$ and that the collision between balls or between balls and supports are elastic. If one ball is struck horizontally so as to acquire a speed v, the average force felt by the support is 
1299290_d7b92577c587474fa13923eeaaeb0893.PNG
  • $$\dfrac { 5m }{ L-5r } $$
  • $$\dfrac { m{ v }^{ 2 } }{ L-10r } $$
  • $$\dfrac { 5m{ v }^{ 2 } }{ L-10r } $$
  • $$\dfrac { m{ v }^{ 2 } }{ L-5r } $$
Two bodies of masses $$4kg$$ and $$16kg$$ are at rest. The ratio of times for which the same force must act on them to produce the same kinetic energy in both of them is
  • $$1:4$$
  • $$2:1$$
  • $$1:2$$
  • $$4:1$$
does not vary from point to point in space Which pair of the following forces will never give resultant force of 2 N?
  • 1 N and 3 N
  • 2 N and 2 N
  • 1 N and 1 N
  • 1 N and 4 N
A hollow smooth uniform sphere $$A$$ of mass $$m$$ rolls without sliding on a smooth horizontal surface. It collides elastically and head-on with another stationary smooth hollow sphere $$B$$ of the same mass mm and same radius. The ratio of the kinetic energy of $$B$$ to that of $$A$$ just after the collision is 
1361865_11e6976e511a4024abd91ae2aaca3faf.PNG
  • $$1 : 1$$
  • $$2 : 3$$
  • $$3 : 2$$
  • $$\rm{None}$$
If body of mass 2 kg is moving along X axis under an external force, whose displacement is given by $$x(t) = 3t^2 - 2t + 5 m$$. Find the work done by force from t = 0 to t = 5 sec.
  • $$78\quad J$$
  • $$780\quad J$$
  • $$840\quad J$$
  • $$200\quad J$$

The work done by a force $$F=(-6x^3\hat
i)$$ in displacing a particle from $$x = 4m$$ to $$x = -2m$$ is:     
  • $$- 240$$ J
  • $$360$$ J
  • $$420$$J
  • will depend upon the path
A force $$\vec { F } = 2 x \hat { i } + 3 y ^ { 2 } \hat { j } \mathrm { N }$$ where x and y are in meter, acts upon a particle. Find work done (in J) by this force in displacing the particle from (1 m, 2 m, 5 m) to (2 m, 3 m, 2 m).
  • 24
  • 16
  • 28
  • 22
A particle moves in a potential region given by $$U = 8{x^2} - 4x + 400\,J.$$ Its state of equilibrium will be$$-$$ 
  • 8 m
  • 10 m
  • 12 m
  • 0.25 m
Work done by air when it expands from 50 litres to 150 litres at a constant pressure of 2 atmospheres is:
  • $$2\times { 10 }^{ 4 }J$$
  • $$2\times { 10 }0J$$
  • $$2\times { 10 }^{ 5 }\times 100J$$
  • $$2\times { 10 }.5\times 100J$$
Two bodies traveling with velocity $$20ms^{-1}$$ and $$40ms^{-1}$$ have same K.E. If the mass of the body having velocity $$40ms^{-1}$$ is 8 kg the mass of other body is 
  • 8 Kg
  • 16 kg
  • 24 kg
  • 32 kg
A body of mass 1 kg falls from rest through the air, a distance of 200 m and acquires a speed 50 m/s. Work done against air friction is 
  • $$750 J$$
  • $$1250 J$$
  • $$1960 J$$
  • $$3210 J$$
 A block of mass m is oscillating on smooth between two light springs of spring constant K separated by a distance I colliding elastically with the spring.If the velocity of the blocks is increased by an external impulse when it is not touching either of the spring then time period.
1568067_2320ff6e60754aa0be159a50175d380a.png
  • Increases
  • Decreases
  • Remain same
  • Time period is independent of I
How much height must an object of mass $$5kg$$ be lifted to have potential energy $$5000J$$ ?$$[g=10 m/s^2]$$
  • $$100m$$
  • $$50m$$
  • $$120m$$
  • $$110m$$
Two particle of masses $$m$$ and $$2m$$ are colliding elastically as given in figure. If $$V_1$$ and $$V_2$$ speed of particle just after collision then
1612351_adb8fe4fb251468ab03954f0581763f8.png
  • $$V_1 = 11.16 \,m/s, V_2 = 6.31 \,m/s$$
  • $$V_1 = 10.16 \,m/s, V_2 = 5.31 \,m/s$$
  • $$V_1 = 9.16 \,m/s, V_2 = 6.31 \,m/s$$
  • $$V_1 = 6.31 \,m/s, V_2 = 11.16 \,m/s$$
A perfectly elastic ball falls on a horizontal floor from a height in a time $$t$$. It will hit the floor again after a time $$t'$$. The ratio of $$t'$$ and t is 
  • $$1:1$$
  • $$1:2$$
  • $$2:1$$
  • $$1:4$$
A man of mass 20 kg is running in a straight line with velocity 10 m/s. What is value of his kinetic energy?
  • $$10\ J$$
  • $$100\ J$$
  • $$1000\ J$$
  • $$10000\ J$$
An athelete diving off a high spring board can perform a variety of physical moments in the air before entering the water below. Which one of the following parameters will remain constant during the fall? The athelete's:
  • linear velocity
  • linear momentum
  • moment of inertia
  • angular momentum
A body of mass $$3\ kg$$ is moving with a velocity of $$4\ m/s$$ towards left, collides head on with a body of mass $$4\ kg$$ moving in opposite direction with a velocity of $$3\ m/s$$. After collision the two bodies stick together and move with a common velocity, which is:
  • zero
  • $$12\ m/s$$ towards left
  • $$12\ m/s$$ towards right
  • $$\dfrac{12}{7}m/s$$ towards left
If a ball is dropped from rest, it bounces from the floor. The coefficient of restitution is $$0.5$$ and the speed just before the first bounce is $$5\ m/sec$$. The total time taken by the ball to come to rest is:
  • $$2\ sec$$
  • $$1\ sec$$
  • $$1.5\ sec$$
  • $$0.25\ sec$$
A particle of mass $$M$$ is moving in a horizontal circle of radius $$R$$ with uniform speed $$v$$. When it moves from one point to a diametrically opposite point, its:
  • momentum does not change
  • momentum changes by $$2Mv$$
  • $$KE$$ changes by $$Mv^{2}$$
  • none of the above
A gas expands from $$5\ litre$$ to $$205\ litre$$ at a constant pressure $$50\ N/m^{2}$$. The work done is
  • $$2000\ J$$
  • $$1000\ J$$
  • $$10000\ J$$
  • None of these
The block will again collide after time:
  • $$6\ sec$$
  • $$4\ sec$$
  • $$8\ sec$$
  • $$\infty$$
A ball of mass $$m_{1}$$ is moving with velocity $$v$$. It collides head on elastically with a stationary ball of mass $$m_{2}$$. The velocity of ball becomes $$\dfrac{v}{3}$$ after collision, then the value of the ratio $$\dfrac{m_{2}}{m_{1}}$$ is:
  • $$1$$
  • $$2$$
  • $$3$$
  • $$4$$
A particle , moving horizontally , collides perpendicularly at one end of a rod having equal mass and placed on a smooth horizontal surface 
1735684_d2126521ee3040fa933f77de4f3d9fb8.PNG
  • Particle comes to rest if collision is perfectly elastic and center of rod starts to move with the same velocity
  • particle continues to move along the same direction , whatever is the value of e
  • particle may get rebound back
  • velocity of mid-point of the rod will be less than $$ v_0 / 2$$ if the particle gets stuck

1735780_f338602c49d044e2a2c1558bdd188f71.PNG
  • Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
  • Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
  • Assertion is correct but Reason is incorrect
  • Assertion is incorrect but Reason is correct
A body of mass $$8\ kg$$ collides elastically with a stationary mass of $$2\ kg$$. If initial $$KE$$ of moving mass be $$E$$, the kinetic energy left with it after the collision will be:
  • $$0.80\ E$$
  • $$0.64\ E$$`
  • $$0.36\ E$$
  • $$0.08\ E$$
Percentage of energy of cylinder lost due to collision is:
  • zero
  • $$50\%$$
  • $$66.67\%$$
  • $$33.33\%$$
Mark the correct statement(s).
  • The work-energy theorem is valid only for particles
  • The work-energy theorem is an invariant law of physics
  • The work-energy theorem is valid only in inertial frames of reference.
  • The work-energy theorem can be applied in non-inertial frames of reference too.
How many collision are possible between the blocks?
  • $$2$$
  • $$4$$
  • $$27$$
  • $$infinite$$
The potential energy $$\psi$$ in joule, of a particle of mass $$1\ kg$$, moving in the $$x-y$$ plane beys the law $$\psi =3x+4y$$m, where $$(x,y)$$ are the coordinates of the particle in metre. If the particle is at rest at $$(6,4)$$ at time $$t=0$$ , then
  • The particle has constant acceleration.
  • The work done by the external forces, the position of rest of the particle and the instant of the particle crossing the $$x-$$ axis is $$25\ J$$
  • The speed of the particle when it crosses the $$y-$$ axis is $$10\ ms^{-1}$$
  • The coordinates of the particle at time $$t=4$$ are $$(-18,-28)$$
A car is accelerated on a levelled road and attains a speed of $$5$$ times its initial speed. In this process , the kinetic energy of the car:
  • does not change
  • becomes $$4$$ times that of initial kinetic energy
  • becomes $$8$$ times that of initial kinetic energy
  • becomes $$25$$ times that of initial kinetic energy
A stone is thrown upwards as shown in the diagram. When it reaches $$P,$$ which of the following has the greatest value for the stone?
1764149_46e1a30f3d4647b3b5ac1ddd2ab130c8.png
  • its acceleration
  • its kinetic energy
  • its potential energy
  • its weight
Write true or false for the following statements:
If we know the speed and mass of an object, we can find out its kinetic energy.
  • True
  • False
When a stone of mass 'm' falls through a vertical height 'd', the decrease in the gravitational energy is:
  • $$mg/d$$
  • $$mg^2/2$$
  • $$mgd$$
  • $$md/g$$
Potential energy of a person is minimum when:
  • Person is standing
  • Person is sitting on a chair
  • Person is sitting on the ground
  • Person is lying on the ground
An object of mass $$5 \,kg$$ falls from a height of $$5 \,m$$ above the ground. The loss of potential energy of the mass is:
  • $$250 \,J$$
  • $$25 \,J$$
  • $$2.5 \,kJ$$
  • $$50 \,J$$
Write true or false for each statement
A gum bottle lying on a table has no energy.
  • True
  • False
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