NEET Physics Work Energy And Power Class 11 Questions

A truck and a car moving with the same kinetic energy are brought to rest by the application of brakes which provide equal retarding forces. Which of them will come to rest in a shorter distance?

How much mass has to be converted into energy to produce electric power of 500 MW for one hour?

Identify the correct statements from the following: (A) Work done by a man in lifting a bucket out of a well by means of a rope tied to the bucket is negative. (B) Work done by gravitational force in lifting a bucket out of a well by a rope tied to the bucket is negative. (C) Work done by friction on a body sliding down an inclined plane is positive. (D) Work done by an applied force on a body moving on a rough horizontal plane with uniform velocity in zero.

When a conservative force does positive work on a body

A particle acted upon by constant forces 4î + ĵ − 3k̂ and 3î + ĵ − k̂ is displaced from the point î + 2ĵ + k̂ to point 5î + 4ĵ + k̂. The total work done by the forces in SI unit is

A pump on the ground floor of a building can pump up water to fill a tank of volume 30 m³ in 15 min. If the tank is 40 m above the ground, and the efficiency of the pump is 30%, how much electric power is consumed by the pump? (Take g = 10 m s⁻²)

A uniform chain of length 2 m is kept on a table such that a length of 60 cm hangs freely from the edge of the table. The total mass of the chain is 4 kg. What is the work done in pulling the entire chain on the table?

The power of a crane, which lifts a mass of 1000 kg to a height of 20 m in 10 s is: (g = 9.8 m/s²)

The kinetic energies of two similar cars A and B are 100 J and 225 J respectively. On applying breaks, car A stops after 1000 m and car B stops after 1500 m. If Fₐ and F_B are the forces applied by the breaks on cars A and B, respectively, then the ratio Fₐ/F_B is

A bob of heavy mass m is suspended by a light string of length l. The bob is given a horizontal velocity v₀ as shown in figure. If the string gets slack at some point P making an angle θ from the horizontal, the ratio of the speed v of the bob at point P to its initial speed v₀ is:

Two bodies A and B of same mass undergo completely inelastic one dimensional collision. The body A moves with velocity \( v_1 \) while body B is at rest before collision. The velocity of the system after collision is \( v_2 \). The ratio \( v_1 : v_2 \) is:

At any instant of time t, the displacement of any particle is given by 2t−1 (SI unit) under the influence of force of 5N. The value of instantaneous power is (in SI unit):

The potential energy of a long spring when stretched by 2 cm is U. If the spring is stretched by 8 cm, potential energy stored in it will be:

An electric lift with a maximum load of 2000 kg (lift + passengers) is moving up with a constant speed of 1.5 m s⁻¹. The frictional force opposing the motion is 3000 N. The minimum power delivered by the motor to the lift in watts is: (g = 10 m s⁻²)

Water falls from a height of 60 m at the rate of 15 kg/s to operate a turbine. The losses due to frictional force are 10% of the input energy. How much power is generated by the turbine? (g = 10 m/s²)

A mass m is attached to a thin wire and whirled in a vertical circle. The wire is most likely to break when:

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:

Body A of mass 4m moving with speed u collides with another body B of mass 2m, at rest. The collision is head on and elastic in nature. After the collision the fraction of energy lost by the colliding body A is:

When a block of mass M is suspended by a long wire of length L, the length of the wire becomes (L + l). The elastic potential energy stored in the extended wire is:

A moving block having mass m₁ collides with another stationary block having mass 4m. The lighter block comes 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 body initially at rest and sliding along a frictionless track from a height h (as shown in the figure) just completes a vertical circle of diameter AB = D. The height h is equal to

Consider a drop of rain water having mass 1g falling from a height of 1 km. It hits the ground with a speed of 50 m/s. Take ‘g’ constant with a value 10 m/s². The work done by the (i) gravitational force and the (ii) resistive force of air is:

A body of mass 1 kg begins to move under the action of a time dependent force F = (2t î + 3t² ĵ)N, where î and ĵ are unit vectors along x and y axis. What power will be developed by the force at the time t?

Two particles of masses m₁, m₂ move with initial velocities u₁ and u₂. On collision, one of the particles get excited to higher level, after absorbing energy ε. If final velocities of particles be v₁ and v₂ then we must have

A particle of mass m is driven by a machine that delivers a constant power K watts. If the particle starts from rest the force on the particle at time t is

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

A mass m moves in a circle on a smooth horizontal plane with velocity v₀ at a radius R₀. 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 \( \frac{R_0}{2} \). The final value of the kinetic energy is

A block of mass 10 kg moving in x direction with a constant speed of 10 m/s, is subjected to a retarding force F = 0.1x J/m during its travel from x = 20 m to 30 m. Its final KE is

A particle with total energy E is moving in a potential energy regions U(x). Motion of the particle is restricted to the region when:

One coolie takes 1 minute to raise a suitcase through a height of 2 m but the second coolie takes 30 s to raise the same suitcase to the same height. The powers of two coolies are in the ratio: