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Gravity at different places on earth

The centre of earth is equator and if equator is the centre of earth and as we know the gravity is maximum at centre of the earth then why the gravity is less there?

Asked Aishwarya

Answer:

(Evidently, the question is posted out of some misconception or confusion)

Centre of earth means the centre INSIDE THE EARTH, and there the value of g is zero.

At the equator, the distance from the centre is maximum and therefore g is the minimum. Further, the effect of rotation is maximum at the equator as the distance of any particle on the surface is farthest from the axis of rotation at the equator and any object at the equator requires maximum centripetal force which is derived from the gravitational force of earth. Thus in both ways, g is minimum at the equator.

Form of Kepler’s in a different universe!

Mukta asked:

“imagine a planetary system in which gravitational force varied as 1/r instead of 1/r2 .what relation would correspond to KEPLER’S THIRD LAW (SQUARE OF TIME PERIOD / CUBE OF SEMI MAJOR AXIS.?”

(Answer)

If the gravitational force varied as 1/r instead of 1/r2 , then Kepler’s Law of periods would have to be modified accordingly and it would give T proportional to r.

Gravitational force is the weakest force in nature

Nijisha asked:

why gravitational force is considered as weak force?

Prejith Asked:

What is space time?

A question from Gravitation.

Prince Patel Asked:

“Sun have high gravitational energy ,then why planets of solar system doesn’t colloid with sun?”

Answer:

“The planets are moving around the sun and the gravitational force is used in providing the necessary centripetal force (The force required by a body to move in a circular path). As long as the planets are in motion, they will not move towards the sun. A similar explanation hold good for moon going around earth also.”

Why Earth does not collide with the sun?

If our earth rotates around sun in discrete orbits, then why it doesn’t collide with Sun because of gravitational force acting between both bodies ?

Answer:

Earth is moving around the sun in such a way that the distance to be traveled TOWARDS sun is compensated by its circular motion. Therefore, instead of “falling towards” the sun, earth “falls around” and never reaches the sun.

CENTRIPETAL FORCE MISCONCEPTION

For a circular motion centripetal force is required. Is there any other force which could replace centripetal force to obtain a circular motion? (Asked Sajin)

Answer:

centripetal forcePlease note that Centripetal Force is the net force that must be acting towards the centre of the circular path. It may be provided by one or more of the forces of different kinds. It is not a kind of force like the frictional force or gravitational force. In different cases the centripetal force is provided by different forces.

For example, when we whirl a stone tied to the end of a rope in a horizontal plane, the tension in the string provides the centripetal force. Here the real force acting is the tension in the string and its magnitude equals the centripetal force mv^2/r.

Read more at the following links

  1. http://hyperphysics.phy-astr.gsu.edu/hbase/cf.html
  2. http://en.wikipedia.org/wiki/Centripetal_force
  3. http://www.physicsclassroom.com/Class/circles/u6l1c.cfm

Motion of a charge particle in an electric field – Numerical Problem

At t=0 a very small object with mass 0.400mg and charge +9.00μC is travelling at 125 m/s in the -x-direction. The charge is moving in a uniform electric field that is in the +y-direction and that has magnitude E= 895 N/C. The gravitational force on the particle can be neglected. How far is the particle from the origin at t= 7.99 ms.

Hint for solving the above problem:

displacement along X direction; x=-uxt=125 x 7.99/1000

Displacement along Y direction, y=0.5 ay t2

ay=qE/m

s=√(x2+y2)

Just substitute the values and get the answer

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