Advertisements
Advertisements
प्रश्न
If the external force acting on a system have zero resultant, the centre of mass
(a) must not move
(b) must not accelerate
(c) may move
(d) may accelerate.
उत्तर
(b) must not accelerate
(c) may move
If the external force acting on a system has zero resultant,
then, acceleration of centre of mass \[= \frac{\vec{F}_{net}}{M} = 0\]
However, it may move uniformly with constant velocity.
APPEARS IN
संबंधित प्रश्न
A child sits stationary at one end of a long trolley moving uniformly with a speed V on a smooth horizontal floor. If the child gets up and runs about on the trolley in any manner, what is the speed of the CM of the (trolley + child) system?
You are waiting for a train on a railway platform. Your three-year-old niece is standing on your iron trunk containing the luggage. Why does the trunk not recoil as she jumps off on the platform?
Consider the following two statements:
(A) Linear momentum of the system remains constant.
(B) Centre of mass of the system remains at rest.
Consider a system of two identical particles. One of the particles is at rest and the other has an acceleration a. The centre of mass has an Acceleration
In which of the following cases the centre of mass of a rod is certainly not at its centre?
(a) the density continuously increases from left to right
(b) the density continuously decreases from left to right
(c) the density decreases from left to right upto the centre and then increases
(d) the density increases from left to right upto the centre and then decreases.
The structure of a water molecule is shown in figure. Find the distance of the centre of mass of the molecule from the centre of the oxygen atom.
Calculate the velocity of the centre of mass of the system of particles shown in figure.
A car of mass M is at rest on a frictionless horizontal surface and a pendulum bob of mass m hangs from the roof of the cart. The string breaks, the bob falls on the floor, makes serval collisions on the floor and finally lands up in a small slot made in the floor. The horizontal distance between the string and the slot is L. Find the displacement of the cart during this process.
The balloon, the light rope and the monkey shown in figure are at rest in the air. If the monkey reaches the top of the rope, by what distance does the balloon descend? Mass of the balloon = M, mass of the monkey = m and the length of the rope ascended by the monkey = L.
Find the ratio of the linear momenta of two particles of masses 1.0 kg and 4.0 kg if their kinetic energies are equal.
Consider a gravity-free hall in which an experimenter of mass 50 kg is resting on a 5 kg pillow, 8 ft above the floor of the hall. He pushes the pillow down so that it starts falling at a speed of 8 ft/s. The pillow makes a perfectly elastic collision with the floor, rebounds and reaches the experimenter's head. Find the time elapsed in the process.
Solve the following problem.
Four uniform solid cubes of edges 10 cm, 20 cm, 30 cm and 40 cm are kept on the ground, touching each other in order. Locate centre of mass of their system.
Define centre of mass.
In system of two particles of masses 'm1' and 'm2', the first particle is moved by a distance 'd' towards the centre of mass. To keep the centre of mass unchanged, the second particle will have to be moved by a distance ______.
The centre of mass of a system of two particles divides the distance between them ______.
The radius and mass of earth are increased by 0.5%. Which of the following statements are true at the surface of the earth?
A bullet of mass 20 gram is fired from a gun of mass 2.5 kg with a speed of 750 m/s. The magnitude of recoil velocity of the gun is ______.
A mass of 1kg is suspended by a string. It is first lifted up with an acceleration of 4.9 m/s2 and then lowered down with same acceleration. The ratio of tensions in the string in the two cases, respectively is g = 9.8 m/s2 ______.
