### NEET Physics - New - Work, Energy and Power

#### Question - 1

A bullet of mass m fired at 30° to the horizontal leaves the barrel of the gun with a velocity v. The bullet hits a soft target at a height h above the ground while it is moving downward and emerges out with half the kinetic energy it had before hitting the target. Which of the following statements is correct in respect of bullet after it emerges out of the target?

• A The velocity of the bullet remains the same.
• B The velocity of the bullet will be reduced to half its initial value.
• C The velocity of the bullet will be more than half of its earlier velocity
• D The bullet will continue to move along the same parabolic path.

#### Question - 2

A spherical ball A of mass 4 kg, moving along a straight line strikes another spherical ball B of mass 1 kg at rest. After the collision, A and B move with velocities VI m S-1 and V2 m S-I respectively making angles of 30° and 60° with respect to the original direction of motion of A. The ratio $\frac { { v }_{ 1 } }{ { v }_{ 2 } }$ will be

• A $\frac { \sqrt { 3 } }{ 4 }$
• B $​​\frac { 4 }{ \sqrt { 3 } }$
• C $\frac { 1 }{ \sqrt { 3 } }$
• D $\sqrt { 3 }$

#### Question - 3

The potential energy function for a particle executing linear SHM is given by V(x) = $\frac{1}{2}$ where k is the force constant of the oscillator. For k = 0.5 Nm-1 , the graph of V(x) versus x is shown in the figure. A particle of total energy E turns back when it reaches x = ±xm. If V and K indicate the potential energy and kinetic energy, respectively of the particle at x = +xm' then which of the following is correct?

• A V= 0, K= E
• B V= E,K= 0
• C V < E, K = 0
• D V=0,K<E

#### Question - 4

A moving block having mass m, collides with another stationary block having mass 4m. The lighter block fomes to rest after collision. When the initial velocity of the lighter block is v, then the value of coefficient of restitution (e) will be:

• A 0.8
• B 0.25
• C 0.5
• D 0.4

#### Question - 5

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 12m is:

• A 18 J
• B 21 J
• C 26 J
• D 13 J

#### Question - 6

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?

• A 8 J
• B 11 J
• C 5 J
• D 2 J

#### Question - 7

Two identical balls A and B having velocities of 0.5 m/s and - 0.3 m/s respectively collide elastically in one dimension. The velocities of  B and A after the collision respectively will be :

• A - 0.5 m/s and 0.3 m/s
• B 0.5 m/s and - 0.3 m/s
• C - 0.3 m/s and 0.5 m/s
• D 0.3 m/s and 0.5 m/s

#### Question - 8

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

• A 0.2 m/s2
• B 0.1 m/s2
• C 0.15 m/s2
• D 0.18 m/s2

#### Question - 9

Two spherical bodies of mass M and 5M and radii Rand 2R respectively are released in free space with initial separation between their centres equal to 12R. If they attract each other due to gravitational force only, then the distance covered by the smaller body before collision is:

• A 7.5 R
• B 4.5 R
• C 2.5 R
• D 1.5 R

#### Question - 10

On a frictionless surface, a block of mass M moving at speed v collides elastically with another block of same mass M which is initially at rest. After collision the first block moves at an angle $\theta$ to its initial direction and has a speed v/3. The second block's speed after the collision is:

• A $\sqrt{3}/2v$
• B $2\sqrt{2}/3v$
• C 3/4v
• D $3/\sqrt{2}$v