Posts

For a two body system in absence of external forces, the kinetic energy as measured from ground frame is 𝐾_0 and from centre of mass frame is 𝐾_𝐶𝑀. Pick up the CORRECT statement. 1. The kinetic energy as measured from center of mass frame is least 2. Only the portion of energy 𝐾_𝐶𝑀 can be transferred from one form to another due to internal changes in the system. 3. The system always retains at least 𝐾_0- 𝐾_𝐶𝑀 amount of kinetic energy as measured from ground frame irrespective of any kind of internal changes in the system. 4. The system always retains at least K c m 𝐾 𝑐 𝑚 amount of kinetic energy as measured from ground frame irrespective of any kind of internal changes in the system.

Education is a part of Life
Post a Comment
WE COME TO NXT WEB

A man of mass `80 kg` stands on a plank of mass `40 kg`. The plank is lying on a smooth horizontal floor. Initianlly both are at rest. The man starts walking on the plank towards north and stops after moving a distance of `6 m` on the plank. Then 1. The centre of mass of plank-man system remains stationary 2. The plank will slide to the north by a dsitance `4m` 3. The plank will slide to the south by a distance `4 m` 4. The plank will slide to the south by a distance `12 m`

Education is a part of Life
Post a Comment
WE COME TO NXT WEB

Assuming potential energy ‘U’ at ground level to be zero. All objects are made up of same material. UP = Potential energy of solid sphere UQ = Potential energy of solid cube UR = Potential energy of solid cone US = Potential energy of solid cylinder US > UP  (B) UQ > US  (C) UP > UQ (D) US > UR

Education is a part of Life
Post a Comment
WE COME TO NXT WEB

The centre of mass of a system of particles is at the origin. Which of the following statement is incorrect . The number of particle to the righ of the origin is equal to the number of particles to the left The total mass of the particles to the right of the origin is same as the total mass to the left of the origin The number of particles on X-axis should be equal to the number of particles on Y-axis If there is a particle on the positive X-axis, there must be at least one particle on the negative X-axis.

Education is a part of Life
Post a Comment
WE COME TO NXT WEB

A rocket of mass 4000 kg is set for vertical firing. How much gas must be ejected per second so that the rocket may have initial upwards acceleration of magnitude 19.6 m/s2 . [Exhaust speed of fuel = 980 m/s.]. (1) 240 kg s –1  (2) 60 kg s –1  (3) 120 kg s –1  (4) 130 kg s –1 

Education is a part of Life
Post a Comment
WE COME TO NXT WEB

A balloon having mass 'm' is filled with gas and is held in hands of a boy. Then suddenly it gets released and gas starts coming out of it with a constant rate. The velocity of the ejected gas is 2m/s with respect to the balloon. Find out the velocity of the balloon when the mass of gas is reduced to half :( neglect gravity) ln2 2ln4 2ln2 None of these

Education is a part of Life
Post a Comment
WE COME TO NXT WEB

A wagon filled with sand has a hole so that sand leaks through the bottom at a constant rate λ. An external force 𝐹 ⃗ acts on the wagon in the direction of motion. Assuming instantaneous velocity of the wagon to be 𝑉 ⃗ and initial mass of system to be m0, the force equation governing the motion of the wagon is 𝐹 ⃗ = 𝑚_0 (𝑑𝑉 ⃗" " )/𝑑𝑥 + λ𝑉 ⃗ 𝐹 ⃗ = 𝑚_0 (𝑑𝑉 ⃗" " )/𝑑𝑥 - λ 𝑉 ⃗ 𝐹 ⃗ = (𝑚_0−"λ " 𝑡)(𝑑𝑉 ⃗" " )/𝑑𝑥 (𝑚_0−"λ " 𝑡)(𝑑𝑉 ⃗" " )/𝑑𝑥 + λ 𝑉 ⃗

Education is a part of Life
Post a Comment
WE COME TO NXT WEB

The carriage of mass M has constant initial velocity u along a straight horizontal track when at t=0. it starts raining. The rain drops have a vertical velocity u′ and result into addition of mass in per second to the carriage. The velocity of ear after T second of start of rain is (Asume frictionlews surface): see the sheet

Education is a part of Life
Post a Comment
WE COME TO NXT WEB

An open water tight railway wagon of mass 5 × 〖"10" 〗^"3" kg coasts at an initial velocity 1.2 m/s without friction on a railway track. Raindrops fall vertically down wards into the wagon. The velocity of the wagon after it has collected 〖"10" 〗^"3" kg of water will be 0.5 m/s  (B) 2 m/s  (C) 1 m/s  (D) 1.5 m/s

Education is a part of Life
Post a Comment
WE COME TO NXT WEB

A bead of mass m and diameter d is sliding back and forth with velocity v on a wire held between two right walls of length L. Assume that th ecollisions with the wall are perfectly elastic and there is no friction. The average force that the bouncing bead exerts on the one of the walls is : mv^2/(𝑙−𝑑) mv^2/(𝑙+𝑑) 〖2mv〗^2/(𝑙−𝑑) 〖2mv〗^2/(𝑙+𝑑)

Education is a part of Life
Post a Comment
WE COME TO NXT WEB