Contents

**NEET Physics Chapter Wise Mock Test – Work, Energy and Power**

**Question 1:
**A bicyclist comes to a skidding stop in 10 m. During this process, the force on the bicycle due to the road is 200 N and is directly opposed to the motion. The work done by the cycle on the road is

(a) +2000 J

(b) -200 J

(c) Zero

(d) -20000 J

**Question 2:
**

**Question 3:
**

**Question 4:
**

**Question 5:
**

**Question 6:
**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}. The work done in the process is

(a) 70 J

(b) 270 J

(c) 35J

(d) 135 J

**Question 7:
**A body of mass 10 kg is moving on an inclined plane of inclination 30° with an acceleration 2 ms

^{-2}. The body starts from rest, the work done by force of gravity in 2 s is

(a) 10 J

(b) zero

(c) 98 J

(d) 196 J

**Question 8:
**

**Question 9:
**300 J of work is done in sliding a 2 kg block up an inclined plane of height 10 m. Taking g = 10 ms

^{-2}, work done against friction is

(a) 200J

(b) 100J

(c) zero

(d) 1000J

**Question 10:
**A car moving with a speed of 50 kmh

^{-1 }can be stopped by brakes after at least 6 m. If the same car is moving with 100 kmh

^{-1}, the minimum stopping distance is

(a) 4 m

(b) 16 m

(c) 24 m

(d) 20 m

**Question 11:
**

**Question 12:
**

**Question 13:
**

**Question 14:
**When a bullet of mass 10 g and speed 100 ms

^{-1}penetrates up to distance 1 cm in a human body in rest. The resistance offered by human body is

(a) 2000 N

(b) 1500 N

(c) 5000N

(d) 1000N

**Question 15:
**The momentum of a body is increased by 20%. The percentage increase in kinetic energy is

(a) 54%

(b) 44%

(c) 100%

(d) 50%

**Question 16:
**

**Question 17:
**A block of mass 10 kg is moving in x-direction with a constant speed of 10ms

^{-1}. It is subjected to a retarding force F = – 0.1x Jm

^{-1}, during its travel from x = 20 m to x = 30 m. Its final kinetic energy will be

(a) 475 J

(b) 450 J

(c) 275J

(d) 250J

**Question 18:
**

**Question 19:
**

**Question 20:
**A man weighing 60 kg climbs a staircase carrying a 20 kg load on his hand. The staircase has 20 steps and each step has height of 20 cm. If he takes 20 s to climb, his power is

(a) 160 W

(b) 230 W

(c) 320W

(d) 80W

**Question 21:
**

**Question 22:
**

**Question 23:
**A spring of spring constant 5 x 103 Nm

^{-1}is stretched initially by 5 cm from the unstretched position. Then, the work required to stretch it further by another 5 cm is

(a) 12.50 Nm

(b) 18.75 Nm

(c) 25.00 Nm

(d) 6.25 Nm

**Question 24:
**

**Question 25:
**

**Question 26:
**For inelastic collision between two spherical rigid bodies

(a) the total kinetic energy is conserved

(b) the total mechanical energy is not conserved

(c) the linear momentum is not conserved

(d) the linear momentum is conserved

**Question 27:
**A moving neutron collides with a stationary α-particle. The fraction of the kinetic energy lost by the neutron is

(a) 16/25

(b) 9/25

(c) 3/5

(d) 2/5

**Question 28:
**

**Question 29:
**A block of mass m moving at a velocity v collides with another block of mass 2m at rest. The lighter block comes to rest after collision. Find the coefficient of restitution.

(a) 1/2

(b) 1

(c) 1/3

(d) 1/4

**Question 30:
**A particle A suffers on oblique elastic collision with a particle B that is at rest initially. If their masses are the same, then after the collision

1. their KE may be equal

2. A continuous to move in the original direction while 6 remains at rest

3. they will move in mutually perpendicular directions

4. A comes to rest and B starts moving in the direction of the original motion of A

(a) 1,3

(b) 2, 3

(c) 1,2

(d) 1,2, 3

**Question 31:
**

**Question 32:
**

**Question 33:
**A high altitude, a body explodes at rest into two equal fragments with one fragment receiving horizontal velocity of 10 m/s. Time taken by the two radius vectors connecting point of explosion of fragments to make 90° is

(a) 10 s

(b) 4s

(c) 2s

(d) 1 s

**Question 34:
**

**Question 35:
**A block of mass 10 kg, moving in x-direction with a constant speed of 10ms

^{-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

(a) 475 J

(b) 450 J

(c) 275J

(d) 250J

**Question 36:
**

**Question 37:
**

**Question 38:
**

**Question 39:
**A body of mass (4 m) is lying in xy-plane at rest. It suddenly explodes into three pieces. Two pieces each of mass m move perpendicular to each other with equal speeds v. The total kinetic energy generated due to explosion is

(a)mv

^{2}

(b) 3/2 mv

^{2}

(c) 2mv

^{2}

(d) 4mv

^{2}

**Question 40:
**A uniform force of (3i + j) N acts on a particle of mass 2 kg. Hence, the particle is displaced from position (2i + k) m to position (4i + 3j – k) m. The work done by the force on the particle is

(a) 9 J

(b) 6 J

(c) 13 J

(d) 15J

**Question 41:
**An explosion breaks a rock into three parts in a horizontal plane. Two of them go off at right angles to each other. The first part of mass 1kg moves with a speed of 12 ms-1 and the second part of mass 2 kg moves with 8 ms 1 speed. If the third part flies off with 4 ms-1 speed, then its mass is

(a) 3 kg

(b) 5 kg

(c) 7 kg

(d) 17 kg

**Question 42:
Assertion (A):** The change in kinetic energy of a particle is equal to the work done on it by the net force.

**Reason (R):**Change in kinetic energy of a particle is equal to the work done only in case of a system of one particle.

(a) If both Assertion and Reason are true and Reason is the correct explanation of Assertion

(b) Both Assertion and Reason are true but Reason is not ’ the correct explanation of Assertion

(c) If Assertion is true but Reason is false

(d) Both Assertion and Reason are false

### Answers:

### Hints And Solutions: