Defining Kinetic Energy

Q.

A running man has half the kinetic energy of that of a boy of half of his mass. The man speeds up by 1 m/s so as to have same K.E. as that of boy. The original speed of the man will be

1. 

2. 

3. 

4. 

Q.

A light and a heavy body have equal kinetic energy. Which one has a greater momentum ?

1. The light body

2. The heavy body

3. Both have equal momentum

4. It is not possible to say anything without additional information

Q.

A body of mass 10 kg at rest is acted upon simultaneously by two forces 4N and 3N at right angles to each other. The kinetic energy of the body at the end of 10 sec is

1. 100 J

2. 300 J

3. 50 J

4. 125 J

Q.

If the momentum of a body is increased n times, its kinetic energy increases

1. 3n

2. 

3. n times

4. 2n times

Q. A 1 kg block and a 0.5 kg block move together ona horizontal frictionless surface. Each block exertsa force of 6 N on the other. The blocks move witha uniform acceleration ofF1 kg 0.5 kg(1) 3 m/s2(3) 9 m/s2(2) 6 m/s2(4) 12 m/s2lt hola is nierc

Q. An electron and a proton are detected in a cosmic ray experiment, the first with kinetic energy 10 keV, and the second with 100 keV. Which is faster, the electron or the proton ? Obtain the ratio of their speeds. (electron mass = 9.11×10¯³¹ kg, proton mass = 1.67×10¯²⁷ kg, 1 eV = 1.60 ×10¯¹⁹ J).

Q. 101 two unequal and opposite force are applied tangentionally to form a uniform disc of mass m and radius r.if the disc is pivotedc at its centre and is free to rotate in its plane, the angular acceleration of the disc is ?

Q.

Two masses of 1g and 9g are moving with equal kinetic energies. The ratio of the magnitudes of their respective linear momenta is

1. 1 : 9

2. 9 : 1

3. 1 : 3

4. 3 : 1

Q. a block of mass 10 kg is held at rest against a rough vertical wall of coefficeint 0.5 under thr action a force F at an angle of 30 degree .the minimum value of F is

Q. A uniform sphere of mass M and radius R is placed on a smooth horizontal ground. The angular acceleration of sphere if force F is applied on it at a distance (7/5)R from ground level is

Q. A cube of mass 2kg is held stationary against a rough wall by a force F=40N passing through centre C . Find perpendicular distance of normal reaction between wall and cube from point C .Side of the cube is 20 cm .Take g=10 ms-2 .

Q. 48. system is shown in figure.all the surfaces are smooth.rod is moved by external agent with acceleration 9m/s2 vertically downwards.force exerted on the rod by the wedge will be

Q.

A light and a heavy body have equal momenta. Which one has greater K.E

1. The light body

2. The heavy body

3. The K.E. are equal

4. Data is incomplete

Q. A homogeneous disk with a radius R = 0.2m and a mass m = 5kg rotates about an axis passing through its center. The time dependence of the angular velocity of the disk rotation is expressed by the equation ω = A+Bt, where B = 8rad/s 2 . Assume there is no friction. 1) Calculate the angular acceleration of the disk. 2) Calculate the tangential force applied to the disk rim. 3) Draw a drawing showing all the vector and scalar quantities used in the problem.

Q. A block of mass 250g slides down an incline of inclination 37 degree with a uniform speed. Find the workdone against the friction as the block slides through 1m.

Q. A 2kg block is placed over a 4kg block and both are placed on a smooth horizontal surface The coefficient of friction between the blocks is 0.20. The acceleration of the two blocks if a horizontal force of 12N is applied to the lower block is (g=10) explain concept clearly?

Q. 46.A ball weighing 10 gram hits a hard surface vertically with a speed of 5 metre per second and rebounds with the same speed the ball remain in contact with the surface for 0.01 second the average force exerted by the surface on the ball is

Q.

A 300 g mass has a velocity of $(3\hat{i}+4\hat{j})m/s$ at a certain instant. What is its kinetic energy?

1. 1.35 J

2. 2.4 J

3. 3.75 J

4. 7.35 J

Q. Kinetic energy is the energy possessed by a body by the virtue of its motion.

1. False
2. True

Q. A force of F N is applied on a ring at a height R/2 above its centre. Find the acceleration of the centre of mass

Q. The total work done on a particle is equal to the change in its kinetic energy. This is applicable

1. always
2. only if the conservative forces are acting on it
3. only in inertial frames
4. only when pseudo forces are absent

Q. The potential energy function for a particle executing linear simple harmonic motion is given by $V\left(x\right)=k{x}^2/2$, where k is the force constant of the oscillator.

Q. 29.A rod of mass 2 kg and length 16 cm is placed horizontally inside a smooth hollow sphere of inner radius 10 cm. The magnitude of normal reaction force between sphere and rod at each end of rod is

Q.

A 300 g mass has a velocity of $(3\hat{i}+4\hat{j})m/s$ at a certain instant. What is its kinetic energy

1. 2.4 J

2. 3.75 J

3. 1.35 J

4. 7.35 J

Q. Keeping the banking angle of the road constant, the maximum safe speed of passing vehicles is to be increased by 10%. The radius of curvature of the road will have to be changed from 20 m to :-

1. 16m
2. 18m
3. 30.5 m
4. 24.20 m

Q. A particle moves on a rough horizontal ground with some initial velocity $v_0$. If ${\left(\frac{3}{4}\right)}^{th}$ of its kinetic energy is lost due to friction between the particle and the ground in time interval $t_0$, then find the coefficient of kinetic friction between the particle and ground. (Assume only kinetic friction is acting on the particle)

1. $\frac{v_0}{2g{t}_0}$
2. $\frac{v_0}{4g{t}_0}$
3. $\frac{3v_0}{4g{t}_0}$
4. $\frac{v_0}{g{t}_0}$

Q. A running man has the same kinetic energy as that of a boy of half his mass. The man speeds up by $2\text{m/s}$ and the boy changes his speed by $x\text{m/s}$ so that the kinetic energies of the boy and the man are again equal. Then $x$ in $\text{m/s}$ is

1. $3\sqrt{2}$
2. $2\sqrt{2}$
3. $\sqrt{2}$
4. $2$

Q. The momentum $P$ and kinetic energy $E$ of a body of mass $m$ are related as:

1. $P=\sqrt{2mE}$
2. $P=\frac{1}{2}mE$
3. $P=\frac{2m}{E}$
4. $P=2mE$

Q. A bomb of mass $16\text{kg}$ at rest explodes into two pieces of masses $4\text{kg}$ and $12\text{kg}$. The velocity of the $12\text{kg}$ mass is $4{\text{ms}}^{-1}$. The kinetic energy of the other mass is

1. $144\text{J}$
2. $288\text{J}$
3. $192\text{J}$
4. $96\text{J}$

Q. Two bodies of masses ${}^{\prime }{m}^{\prime }$ and ${}^{\prime }4m^{\prime }$ are having linear momentum in the ratio of $2:1$, respectively. The ratio of their kinetic energy is

1. $4:1$
2. $1:4$
3. $1:8$
4. $16:1$