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# Tag Archives: acceleration due to gravity

## 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?

(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.

## Gravity on moon

We know that the first man to walk on moon was Neil Armstrong. it is said that there is  no force of gravity on moon. then how did Neil Armstrong moved a few steps on moon?

Who says there is no gravity in moon?

The acceleration due to gravity on moon is 1/6 that on earth.

I feel that you are confused by the concept of weightlessness in satellites.

On moon, it has its own gravity which is one sixth that on earth.

## Motion under gravity and time of fall

A body of mass m1 and another body of mass m2 are dropped from wqual heights.If time taken by the balls are t1 and t2 respectively then t1=t2. How ?

The acceleration due to gravity is independent of mass of body. When two different masses  are dropped from the  same height, they will take same time  to reach the surface of earth.

## Motion under gravity

Two stones of mass 5 kg and 10 kg are dropped from the same height above the ground level. Which one will hit the ground first? Why?

Answer: Both the stones will reach the ground simultaneously (provided we neglect the air resistance (the viscosity) and buoyant force.

This is because acceleration due to gravity is independent of mass of the freely falling body.

## How the value of acceleration due to gravity will change if the radius of earth is doubled keeping its density constant?

How the value of acceleration due to gravity will change if the radius of earth is doubled keeping its density constant?

## Acceleration due to gravity problem

A body weighs 30 kg on the surface of the earth how much would it weigh on the surface of a planet whose mass is 1/9 the mass of earth and radius is half of that of earth?

Weight on earth = 30 kg wt = 30 x g N

g on new planet, g’ = GM’/R’2=(4/9)g

Therefor weight on the new planet will be equal to 4/9 times its weight on earth

(Whereas the mass will be the same)

## Acceleration of a body on a rough surface

A black of mass 1.5kg placed on a rough horizontal surface is pulled by a constant horizontal force of 1.2kg wt. the cofficient of friction between the block and the surface is 0.3.  Find acceleration produced in terms of g.

(Posted by Ankur Srivastava)

Applied force, F=1.2 kg wt = 1.2g N (where g is the acceleration due to gravity)

Friction f=µmg=0.3 x 1.5 x g=0.45g N

The net force = ma

Therefore;

ma= F-f

=> 1.5 x a = 1.2 g -0.45g=0.8 g

or

a = (0.8/1.5)g

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