Tag: turning effects of forces

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Questions Related to turning effects of forces

Multiple choice physics turning effects of forces stability and centre of mass center of mass centre of mass

If a square of side $\dfrac{R}{2}$ is removed from a uniform circular disc of radius R as shown in the figure, the shift in centre of mass is 

  1. $\dfrac{R}{4 \pi - 1}$

  2. $\dfrac{R}{2(4 \pi - 1)}$

  3. $\dfrac{R}{3(4 \pi - 1)}$

  4. $\dfrac{R}{4(4 \pi - 1)}$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The shift in the center of mass is calculated using the principle of negative mass. The mass of the removed square is proportional to its area, and the shift is (m_removed * distance) / (M_total - m_removed).

Multiple choice physics turning effects of forces stability and centre of mass center of mass centre of mass

Which of the following is not correct about centre of mass ?

  1. It depends on the choice of frame of reference

  2. In centre of mass frame, momentum of a system is always zero

  3. Internal forces may affect the motion of centre of mass

  4. Centre of mass and centre of gravity coincide in uniform gravitational field
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The internal forces all balance each other so that there is no change in the mass distribution of the body, thus center of mass remains unchanged. Rest all options are correct.

Multiple choice physics turning effects of forces stability and centre of mass center of mass centre of mass

A point at which a whole weight of body act vertically downward is ________.

  1. centre of gravity

  2. centre of mass

  3. centre of force

  4. centre of acceleration
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The center of gravity is the point where the total gravitational force (weight) of a body is considered to act. While often coincident with the center of mass, the definition specifically refers to weight.

Multiple choice physics turning effects of forces stability and centre of mass center of mass centre of mass

In classical system:

  1. the varying mass system is not considered

  2. the varying mass system must be considered

  3. the varying mass system may be considered

  4. only varying of mass due to velocity is considered
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Classical mechanics is a broad framework that can accommodate varying mass systems, such as rockets or chains, through the application of Newton's second law in the form F = dp/dt.

Multiple choice physics turning effects of forces stability and centre of mass center of mass centre of mass

Statement 1: When we lean behind over the hind legs of the chair, the chair falls back after a certain angle.

Statement 2: Centre of mass lying outside the system makes the system unstable.

  1. Statement 1 is false, Statement 2 is true

  2. Statement 1 is true, Statement 2 is true; Statement 2 is a correct explanation for Statement 1

  3. Statement 1 is true, Statement 2 is true; Statement 2 is not a correct explanation for Statement 1

  4. Statement 1 is true, Statement 2 is false
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
The chair falls down after a certain angle because it becomes unstable as the normal reaction by ground on chair becomes zero.
There are several mechanical structure whose COM lies outside its body but they are quite stable.

So option D is correct.
Multiple choice physics turning effects of forces stability and centre of mass center of mass centre of mass

On a stationary sail boat, air is blown at the sails from a fan attached to the boat. The boat will

  1. remain at rest

  2. spin round

  3. move in the direction in which air is blown

  4. move in a direction opposite to that in which air is blown
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

the boat will remain at the rest  because the thrust or recoil force of fan at boat and force of air on the sails will cancel each other and boat will not at all move .

so the answer is A.

Multiple choice physics turning effects of forces stability and centre of mass center of mass centre of mass

The passengers in a boat are not allowed to stand because: 

  1. This will raise the centre of gravity and the boat will be rocked

  2. This will lower centre of gravity and the boat will rocked

  3. The effective weight of system increases

  4. Of surface tension effects
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

when passengers stands up on the boat from the sitting situation , the centre of gravity moves upwards and it increases the chances of toppling of boat .

so the answer is A.

Multiple choice physics turning effects of forces stability and centre of mass center of mass centre of mass

The point through which the total weight of an object appears to act for any orientation of the object is ______.

  1. Centre of buoyancy

  2. Centre of gravity

  3. Centre of curvature

  4. Median of a triangle
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The point through which the total weight of an object appears to act for any orientation of the object is centre of gravity.

Multiple choice physics turning effects of forces stability and centre of mass center of mass centre of mass
State whether true or false.
The position of centre of gravity of an object depends on the acceleration due to gravity at the given place.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
The center of gravity is a geometric property of any object. The center of gravity is the average location of the weight of an object with mass.
Therefore the position of centre of mass has nothing to do with the acceleration due to gravity.
So, the statement is FALSE