Tag: motion of system of particles and rigid bodies

Quizzes (12) Questions (32)

Questions Related to motion of system of particles and rigid bodies

Multiple choice physics motion of system of particles and rigid bodies centre of gravity turning effects of forces forces - vectors and moments

What is the position of centre of gravity of a cylinder?

  1. At the center of base circle

  2. At the center of top circle

  3. Cannot be determined

  4. At the mid point on the axis of cylinder
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Centre of gravity means a point from which the weight of a body or system may be considered to act. In uniform gravity it is the same as the centre of mass. For regular shaped bodies it lies at the centre of the that particular body. Hence for a cylinder centre of gravity lies at the midpoint of the axis of the cylinder.

Multiple choice physics motion of system of particles and rigid bodies centre of gravity turning effects of forces forces - vectors and moments

In an artificial satellite, the use of a pendulum watch is discarded, because :

  1. The satellite is in a constant state of motion

  2. The effective value of $g$ becomes zero in the artificial satellite

  3. The periodic time of the pendulum watch is reduced

  4. None of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A pendulum watch relies on gravity to oscillate. Inside an orbiting satellite, objects are in a state of free fall, meaning the effective gravitational acceleration (g) is zero, causing the pendulum to stop oscillating.

Multiple choice physics motion of system of particles and rigid bodies centre of gravity turning effects of forces forces - vectors and moments

Given that there is a relationship between the orbital radius of a planet and its period of revolution and that the periods of revolution of Mercury, Earth, Jupiter and Neptune and nearly 0.24, 1, 11.8 and 165 years. It follows that the period of revolution of
1. Venus is less than 0.24 years
2. Mars is less than 12 years
3. Uranus is more than 165 years
4. Uranus is less than 165 years but more than 12 years.

  1. 1 and 3

  2. 4 only

  3. 3 o nly

  4. 2 and 4
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Kepler's third law states that the square of the orbital period is proportional to the cube of the semi-major axis (distance from the Sun). Therefore, planets further from the Sun have longer orbital periods. Mars (between Earth and Jupiter) must have a period between 1 and 11.8 years. Uranus (further than Neptune) would have a period longer than 165 years. The logic in option 2 and 4 fits the observed orbital distances.

Multiple choice rotational equilibrium option b: engineering physics motion of system of particles and rigid bodies equilibrium physics

Consider the following statements:
(a)  Change in momentum is impulse.
(b)  A body is momentarily at rest when it reverse the direction.
(c)  For stable equilibrium force has to be zero and potential energy should be minimum.
(d)  Force required to accelerate a mass in two perpendicular directions is never same.
Which of the above statements are correct?

  1. (b) and (c)

  2. (a) and (b)

  3. (a), (b) and (d)

  4. All of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

All of the above
Impulse = Force$\times$time = $m\Delta{v}$ = Momentum
A body will be at rest for a moment when it changes direction.
When a body is in equilibrium it always has minimum potential energy and no force is acting upon it.
Force is a vector quantity and hence its direction will result in different force quantity.

Multiple choice rotational equilibrium option b: engineering physics motion of system of particles and rigid bodies equilibrium physics

State whether given statement is True or False.

When any object is in equilibrium, the sum of all the forces acting on it is zero.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

When an object is not in equilibrium, net force acting on the body is not zero.
Therefore when some force acts on the object, it is in accelerated motion because, $F= ma$

Multiple choice rotational equilibrium option b: engineering physics motion of system of particles and rigid bodies equilibrium physics

When a body remains in the state of rest conditions under the influence of applied forces, the body is in 

  1. Dynamic equilibrium

  2. Static equilibrium

  3. Both

  4. None
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The equilibrium is of two types
(1) Static equilibrium
(2) Dynamic equilibrium
When a body remains in the state of rest under the influence of the applied forces, the body is in static equilibrium.

Multiple choice rotational equilibrium option b: engineering physics motion of system of particles and rigid bodies equilibrium physics

A body is in translatory equilibrium if:

  1. Resultant force on it is zero

  2. It is at rest

  3. It is in uniform motion

  4. All options are correct
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

A body is said to be in translatory equilibrium when net external force acting on it is zero.

Also if no external force is acting on the body, then the body must be at rest or moving with constant velocity i.e moves in uniform motion. Hence option D is correct.