Work and Energy — NEET Physics PYQ MCQs with Solutions

A particle is released from height $S$ from the surface of the Earth. At a certain height its kinetic energy is three times its potential energy. The height from the surface of earth and the speed of the particle at that instant are respectively

The energy required to break one bond in DNA is $10^{-20}$ J. This value (in eV) is nearly

A force $F=20+10y$ acts on a particle in $y$-direction, where $F$ is in newton and $y$ in meter. Work done by this force to move the particle from $y=0$ to $y=1$ m is

A particle of mass 10 g moves along a circle of radius 6.4 cm with a constant tangential acceleration. What is the magnitude of this acceleration, if the kinetic energy of the particle becomes equal to $8\times10^{-4}$ J by the end of the second revolution after the beginning of the motion?

A particle moves from a point $(-2\hat{i}+5\hat{j})$ to $(4\hat{j}+3\hat{k})$ when a force of $(4\hat{i}+3\hat{j})$ N is applied. How much work has been done by the force?

Two similar springs $P$ and $Q$ have spring constants $K_P$ and $K_Q$, such that $K_P>K_Q$. They are stretched, first by the same amount (case $a$), then by the same force (case $b$). The work done by the springs $W_P$ and $W_Q$ are related as, in case ($a$) and case ($b$), respectively

A block of mass 10 kg, moving in $x$-direction with a constant speed of 10 ms$^{-1}$, is subjected to a retarding force $F=0.1x$ J/m during its travel from $x=20$ m to 30 m. Its final KE will be

Two particles of masses $m_1, m_2$ move with initial velocities $u_1$ and $u_2$. On collision, one of the particles get excited to higher level, after absorbing energy $\varepsilon$. If final velocities of particles be $v_1$ and $v_2$, then we must have

A mass $m$ moves in a circle on a smooth horizontal plane with velocity $v_0$ at a radius $R_0$. The mass is attached to a string which passes through a smooth hole in the plane as shown. The tension in the string is increased gradually and finally $m$ moves in a circle of radius $\dfrac{R_0}{2}$. The final value of the kinetic energy is

A ball is thrown vertically downwards from a height of 20 m with an initial velocity $v_0$. It collides with the ground, loses 50% of its energy in collision and rebounds to the same height. The initial velocity $v_0$ is (Take, $g=10$ ms$^{-2}$)

A uniform force of $(3\hat{i}+\hat{j})$ N acts on a particle of mass 2 kg. Hence, the particle is displaced from position $(2\hat{i}+\hat{k})$ m to position $(4\hat{i}+3\hat{j}-\hat{k})$ m. The work done by the force on the particle is

The potential energy of a particle in a force field is $U=\dfrac{A}{r^2}-\dfrac{B}{r}$, where $A$ and $B$ are positive constants and $r$ is the distance of particle from the centre of the field. For stable equilibrium, the distance of the particle is

The potential energy of a system increases, if work is done

Force $F$ on a particle moving in a straight line varies with distance $d$ as shown in the figure. The work done on the particle during its displacement of 12 m is

A block of mass $M$ is attached to the lower end of a vertical spring. The spring is hung from a ceiling and has force constant value $k$. The mass is released from rest with the spring initially unstretched. The maximum extension produced in the length of the spring will be

A body of mass 1 kg is thrown upwards with a velocity $20\ \text{ms}^{-1}$. It momentarily comes to rest after attaining a height of 18 m. How much energy is lost due to air friction? (Take $g=10\ \text{ms}^{-2}$)

300 J of work is done in sliding a 2 kg block up an inclined plane of height 10 m. Taking $g=10\ \text{m/s}^2$, work done against friction is

A body of mass 3 kg is under a constant force, which causes a displacement $s$ in metre in it, given by the relation $s=\dfrac{1}{3}t^2$, where $t$ is in second. Work done by the force in 2 s is

A force $F$ acting on an object varies with distance $x$ as shown here. The force is in newton and $x$ is in metre. The work done by the force in moving the object from $x=0$ to $x=6$ m is

A bomb of mass 30 kg at rest explodes into two pieces of masses 18 kg and 12 kg. The velocity of 18 kg mass is $6\ \text{ms}^{-1}$. The kinetic energy of the other mass is

A particle of mass $m_1$ is moving with a velocity $v_1$ and another particle of mass $m_2$ is moving with a velocity $v_2$. Both of them have the same momentum, but their different kinetic energies are $E_1$ and $E_2$ respectively. If $m_1>m_2$, then

A ball of mass 2 kg and another of mass 4 kg are dropped together from a 60 ft tall building. After a fall of 30 ft each towards earth, their respective kinetic energies will be in the ratio of

If kinetic energy of a body is increased by 300%, then percentage change in momentum will be

A stone is thrown at an angle of $45^\circ$ to the horizontal with kinetic energy $K$. The kinetic energy at the highest point is

A child is swinging a swing. Minimum and maximum heights of swing from the earth's surface are 0.75 m and 2 m respectively. The maximum velocity of this swing is

Two bodies with kinetic energies in the ratio $4:1$ are moving with equal linear momentum. The ratio of their masses is

A force acts on a 3.0 g 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 metre and $t$ in second. The work done during the first 4 s is

A rubber ball is dropped from a height of 5 m on a planet where the acceleration due to gravity is not known. On bouncing it rises to 1.8 m. The ball loses its velocity on bouncing by a factor of

If the momentum of a body is increased by 50%, then the percentage increase in its kinetic energy is

The KE acquired by a mass $m$ in travelling a certain distance $d$, starting from rest, under the action of a constant force is directly proportional to