Dynamic Equilibrium

Q.

State two conditions for a body, acted upon by several forces, to be in equilibrium.

Q.

State the condition when the body is in

i) Rotational equilibrium

ii) Translational equilibrium

1. i) The resultant moment of all the forces acting on the body should be zero

   ii) The resultant of all the forces acting on the body should be zero

2. i) The resultant moment of all the forces acting on the body should be positive

   ii) The resultant of all the forces acting on the body should be non-zero

3. i) The resultant moment of all the forces acting on the body should be zero

   ii) The resultant of all the forces acting on the body should be non-zero

4. i) The resultant moment of all the forces acting on the body should be negative.

   ii) The resultant of all the forces acting on the body should be zero

Q. On being slightly disturbed from its equilibrium position, if a body

1. neutral equilibrium
2. stable equilibrium
3. unstable equilibrium

Q.

If two equal and opposite forces have the same line of action, then

1. The resultant force is zero, but the resultant moment is non-zero.

2. The resultant force is non-zero, as well as the resultant moment is non-zero.

3. The resultant force is non-zero, but the resultant moment is zero.

4. The resultant force is zero, as well as resultant moment is zero.

Q. When a body remains in the same state of motion, under the influence of several forces, it is in equilibrium.

1. static
2. dynamic
3. rotational
4. translational

Q.

For a rotational equilibrium also known as a dynamic equilibrium has ___

1. vector sum of torques is zero

2. vector sum of velocities is zero

3. scalar sum of torques is zero

4. scalar sum of angular velocities is zero

Q.

Two birds of exactly same mass are kept in two cages A and B. Cage A is made of glass and cage B is made of wire net. Both cages are kept on a weighting machine . While the birds are sitting on a bar fitted inside the cage the reading of the weighting machine is noted. If the birds now start flying and hovering in air in their cages , how do the readings in the weighting machine change.

Q.

To an observer on the ground the passengers and bus on a level road at constant velocity are an example of

1. static equilibrium.

2. rotational equilibrium

3. dynamic equilibrium

4. translational equilibrium

Q.

Question 19

Fig. shows a man with a parachute. Name the force which is responsible for his downward motion. Will he come down with the same speed without the parachute?

Q.

During a jump from the aeroplane at a particular velocity, the air drag on parachute becomes:

1. less than the weight of the jumper

2. equal to the weight of the jumper

3. greater than the weight of the jumper

4. equal to the weight of the parachute

Q. The speed of clay just before hitting the rod is

1. 10 m/s
2. 10 m/s
3. 2.5 m/s
4. 10 m/s

Q. Why does a body experiences weightless inside a spacecraft or satellite?

Q. For a moving particle, what does decrease in displacement with time indicates ?

1. The particle is moving towards its initial position
2. The particle is moving with uniform speed.
3. The acceleration of the particle is approaching zero
4. The particle is moving with uniform motion.

Q.

Can torque be balanced by a single force?explain