# physics

posted by .

a body of mass 1kg on the equator rotates about the axis of the earth with a period of 1 day. (mass of earth = 5.98x10^24kg n may b assumed to b concentrated at its centre n radius of earth = 6380km)
first question asks to calculate gravitational force of attraction between earth n mass....simple enuff
second qs asks to work out centripetal force on mass...easy
then it asks us to work out the difference between these two forces n use the answer as the resultant force to calucalte g at the equator using F =ma; what i've been taught is centripetal force is the resultant force so then y the need to find resultant force as the qs says. and then wat i also don't understand is why the resultant force is the difference between two forces that are acting in the same direction.
if someone cud clarify id b gr8ful

• physics -

The resultant force that they want is the modified force M g' that a scale would indicate for the object at the equator. It is less than the gravitational weight alone (M g) because

Gravity force - Indicated (scale) weight = Centripetal force
Therefore
Indicated weight = Gravity force - Centripetal force

g' = g - (V^2/R)

What you are really calculating is the resultant of the gravity force and the fictitious centriFUGAL force in the opposite direction.

## Similar Questions

1. ### Physics

The earth rotates once per day about an axis passing through the north and south poles, an axis that is perpendicular to the plane of the equator. Assuming the earth is a sphere with a radius of 6.38 106 m, determine the speed and …
2. ### physics

the earth (mass=5.98x10^24kg) rotates around the sun in a orbit that is approximately circular, with a radius of 1.5x10^11m find the orbital speed of the earth around the sun
3. ### help physics

the earth (mass=5.98x10^24kg) rotates around the sun in a orbit that is approximately circular, with a radius of 1.5x10^11m find the orbital speed of the earth around the sun
4. ### physics??

The earth rotates once per day about an axis passing through the north and south poles, an axis that is perpendicular to the plane of the equator. Assuming the earth is a sphere with a radius of 6.38 x 106 m, determine the centripetal …
5. ### Physics circular motion

The earth rotates once per day about an axis passing through the north and south poles, an axis that is perpendicular to the plane of the equator. Assuming the earth is a sphere with a radius of 6.38 x 106 m, determine the centripetal …
6. ### physics

The earth rotates once per day about an axis passing through the north and south poles, an axis that is perpendicular to the plane of the equator. Assuming the earth is a sphere with a radius of 6.38 x 106 m, determine the centripetal …
7. ### Physics

The earth rotates once per day about an axis passing through the north and south poles, an axis that is perpendicular to the plane of the equator. Assuming the earth is a sphere with a radius of 6.38 106 m, determine the speed and …
8. ### Physics

The earth rotates once per day about an axis passing through the north and south poles, an axis that is perpendicular to the plane of the equator. Assuming the earth is a sphere with a radius of 6.38 106 m, determine the speed and …
9. ### physics

The earth rotates once per day about an axis passing through the north and south poles, an axis that is perpendicular to the plane of the equator. Assuming the earth is a sphere with a radius of 6.38 x 106 m, determine the speed and …
10. ### Physics

Calculate the distance, in m, of the centre of mass of the Earth-Moon system from the centre of the Earth. Note: the mass of the Moon is 7.35x10 22kg, the mass of the Earth is 5.98x10 24kg, and their separation is 3.85x10 8m.

More Similar Questions