estimate the total mass of the earth's atmosphere? (the radius of the earth is 6.37 106 m, and atmospheric pressure at the surface is 1.01 105 n/m2.)

The image shows a pendulum in simple harmonic motion the pendulum starts at a and swing to e

Which changes of state do the labels represent? a: b: c:

Asolid cylinder and a cylindrical shell have the same mass, same radius, and turn on frictionless, horizontal axles. the cylindrical shell has light-weight spokes connecting the shell to the axle. a rope is wrapped around each cylinder and tied to blocks of equal masses that are held the same height above the ground. both blocks are released simultaneously. the ropes do not slip. which block hits the ground first? or is it a tie?