NEET Work Energy and Power MCQs & PYQs

Q: If the kinetic energy of a body is increased by 300%, its momentum will increase by :

Relation between Kinetic Energy and Momentum is P = √(2mK) When kinetic energy is increased by 300 % it becomes 4K so new momentum is P1= √(2m.4K) =2P

Q: If the kinetic energy of a body is increased by 3%, its momentum will increase by :

K = P²/2m so, ∇K/K=2∇P/P Solving We get , ∇P/P = 1.5%

Q: A man pulls a bucket full of water from h metre deep well. If the mass of rope is m and mass of bucket full of water is M, then work done by the man is

Bucket of mass M will rise by a distance of h. While center of mass of the rope rises by height of h/2. So, Work Done = (M+m/2).g.h

Q: In a conservative field, the potential energy U as a function of position x is given by U = x². Then the corresponding conservative force is given by

By definition Force F = -dU/dx, so F = - d(x²)/dx= -2x

Q: An engine pumps 400 kg of water through height of 10 m in 40 s. Find the power of the pump (g = 10 m/s²).

Power = Work Done / Time Taken Here , Work Done = 400 ×10 ×10 J = 40000 J Time Taken = 40 sec , So, Power = 40000/40 = 1000 W= 1 KW

Practice NEET Work Energy and Power Questions

Question 11:

moderate

Two masses of 1 g and 4 g are moving with equal kinetic energies. The ratio of the magnitudes of their linear momenta is

Kinetic Energy is given by K = ½mv² and Momentum is P=m.v, relation between kinetic energy and momentum is

K= P²/2m so P=√(2mK)

So P1/P2= √(m1)/√(m2)= √1/√4 = 1:2

💬 Discuss this Question

Question 12:

moderate

If the kinetic energy of a body is increased by 300%, its momentum will increase by :

Relation between Kinetic Energy and Momentum is

P = √(2mK)

When kinetic energy is increased by 300 % it becomes 4K so new momentum is

P1= √(2m.4K) =2P

💬 Discuss this Question

Question 13:

moderate

If the kinetic energy of a body is increased by 3%, its momentum will increase by :

K = P²/2m so,

∇K/K=2∇P/P

Solving We get , ∇P/P = 1.5%

💬 Discuss this Question

Question 14:

easy

A cubical vessel of height 1 m is full of water. The minimum work done in taking water-out from vessel will be

As side length of cubical tank is 1 m. Volume is 1 m³. Volume of water in 1 m³ is 1000 lit and mass will be 1000 kg.

Height of center of mass of the tank will be 1/2 m.

Potential Energy = 1000 ×10 × 1/2 = 5000 J

💬 Discuss this Question

Question 15:

moderate

A man pulls a bucket full of water from h metre deep well. If the mass of rope is m and mass of bucket full of water is M, then work done by the man is

Bucket of mass M will rise by a distance of h.

While center of mass of the rope rises by height of h/2.

So, Work Done = (M+m/2).g.h

💬 Discuss this Question

Question 16:

moderate

Potential energy of a particle at position x is given by U = x² – 5x. Which of the following is equilibrium position of the particle?

For Equilibrium,

dU/dx = 0

⇒ d(x²-5x)/dx=0

⇒ 2x-5 = 0

⇒ x =2.5 m

💬 Discuss this Question

Question 17:

moderate

In a conservative field, the potential energy U as a function of position x is given by U = x². Then the corresponding conservative force is given by

By definition Force F = -dU/dx, so

F = - d(x²)/dx= -2x

💬 Discuss this Question

Question 18:

easy

Select correct statement regarding stable equilibrium

All the statements are true regarding stable equilibrium

💬 Discuss this Question

Question 19:

moderate

In a certain field, the potential energy is U = ax² – bx³, where a and b constants. The particle is in stable equilibrium at x equal to

Potential Energy is U = ax² – bx³. For Equilibrium F = -dU/dx

⇒ dU/dx= 2ax- 3bx²=0

⇒ x = 2a/3b

💬 Discuss this Question

Question 20:

easy

An engine pumps 400 kg of water through height of 10 m in 40 s. Find the power of the pump (g = 10 m/s²).

Power = Work Done / Time Taken

Here , Work Done = 400 ×10 ×10 J = 40000 J

Time Taken = 40 sec , So,

Power = 40000/40 = 1000 W= 1 KW

💬 Discuss this Question