Is the density of earth uniform throughout?

Density of water is

The amount of usable energy which is available for doing work, when the temperature and pressure are uniform throughout the system, is called

Is the tension in a string on either side of a pulley the same throughout its length ?if yes,under what condition?

Write True or False: Tropical evergreen forests are found in the areas with heavy rainfull throughout the year.

The gravitational force between a hollow spherical shell (of radius R and uniform density) and a point mass is F. Show the nature of F vs r graph whee r is the distance of the point form the centre of the hollow spherical shell of uniform density.

For an oscillating simple pendulum, is the tension constant throughout the oscillation ? If not when it is the least

For an oscillating simple pendulum, is the tension constant throughout the oscillation ? If not when it is the greatest.

Assuming the earth to be a sphere of uniform mass density, how much would a body weigh half way down to the centre of the earth if it weighed 250 N on the surface ?