Tag: physics

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Questions Related to physics

Multiple choice physics turning effects of forces centre of gravity forces - vectors and moments acceleration due to gravity

The centre of gravity of an object is ______ whether it is placed near the surface of the Earth or near the surface of the Moon.

  1. same

  2. different

  3. depend on the situation

  4. none
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Centre of mass is a point on a physical body which behaves as if the whole mass is concentrated over there. Whenever a force acts on a body it appears to be acting on the centre of mass. Whenever gravitational force is acting on a body it appears to be acting on a specific point on the body which is known as the centre of gravity.
 It usually coincides with the centre of mass. Earth being a larger planet than the moon, the gravitational force is more intense on earth as compared to the moon.
 The location of the centre of mass does not vary with the intensity of the force acting on the body. Similarly, centre of gravity does not vary with the intensity of the gravitational force acting on it.  Hence the centre of gravity on earth and moon will be the same

Multiple choice physics turning effects of forces centre of gravity forces - vectors and moments acceleration due to gravity

The center of gravity of an object is 

  1. the sum of its moments divided by the weight of the specific object.

  2. the sum of its moments divided by the overall weight of the object.

  3. the sum of its moments of product of the overall weight of the object.

  4. none of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The center of gravity is defined as the ratio of sum of its moments to the total weight of the object.

Mathematically, center of gravity  $x = \dfrac{m _1 g x _1 + m _2 g x _2 +....m _n g x _n}{(m _1 + m _2 + .....m _n) g}$
$\implies$  $x = \dfrac{m _1  x _1 + m _2  x _2 +.... m _n x _n}{M}$
where overall weight of object $M = m _1 + m _2 +...m _n$

Multiple choice physics turning effects of forces centre of gravity forces - vectors and moments acceleration due to gravity

The advantages of being short and stocky is that you're less likely to get knocked over. This is because

  1. The short and stocky person has a lower center of gravity

  2. The short and stocky person has a larger center of gravity

  3. They have less height and less weight

  4. None of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Since, short person has lower center of gravity hence it is difficult to knocked them out

Multiple choice physics turning effects of forces centre of gravity forces - vectors and moments acceleration due to gravity

Center of gravity is usually located where

  1. less mass is concentrated

  2. less weight is concentrated

  3. more mass is concentrated

  4. more weight is concentrated
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Centre of gravity of an object is a specific point such that the body behaves as if the entire gravitational force is acting only at that point.

Since weight means the gravitational force acting, D is the correct option.
C is not the correct option because, for very large bodies like huge mountains, it is not at the point where more mass is concentrated

Multiple choice physics turning effects of forces centre of gravity forces - vectors and moments acceleration due to gravity

Centre of gravity is the point

  1. where the weight of the object is supposed to be present or concentrated.

  2. where the weight of the object is perpendicular to the surface area of the object.

  3. where maximum no of molecules presents

  4. none of the above

Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

It is a point on which behaves as if the whole weight of the body appears to be concentrated.

Multiple choice physics turning effects of forces centre of gravity forces - vectors and moments acceleration due to gravity

One can lean further to one side or the other without creating enough turning force to tip him over. This is because 

  1. The person has low centre of gravity

  2. The person has no centre of gravity

  3. The person has high centre of gravity

  4. None of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Center of gravity is the point at which the entire weight of a body may be considered as concentrated so that if supported at this point the body would remain in equilibrium.

One can lean further to one side or other without creating enough turning force to tip him over. This is because the person has low center of gravity as having a low center of gravity decreases the torque hence the person will not tip over.

Multiple choice physics turning effects of forces centre of gravity forces - vectors and moments acceleration due to gravity

Statement related to center of gravity that is incorrect is

  1. The center of gravity of an object is defined as the point through which its whole weight appears to act.

  2. The center of gravity is sometimes confused with the center of mass.

  3. The center of gravity always lies inside the object.

  4. For an object placed in a uniform gravitational field, the center of gravity coincides with the center of mass.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In case of a ring, the centre of gravity lies at the centre of the ring. Hence option c is the incorrect option

Multiple choice physics turning effects of forces centre of gravity forces - vectors and moments acceleration due to gravity

What is the center of gravity of an object?

  1. The point where gravity appears to act.

  2. The point where gravity doesn't act.

  3. The point where the force of gravity is strongest.

  4. The point where the force of gravity is weakest.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Option A is the definition of the centre of gravity. B is a contradiction. As far as C ad D are concerned, the force of gravity is equal at all points provided the object is small as compared to the radius of the planet.