SI base unit used to measure the amount of a substance

A Cassegrain telescope has a hole in the main mirror. This reduces the mirror area and thus the light gathering power, but how much? Suppose a ten inch diameter mirror has a one inch diameter hole in the center.

During a total lunar eclipse, the Earth, Sun, and Moon are arranged in a line, and light from the Sun is blocked out of view for a certain part of the Earth by the Moon. In what order do the Earth, Sun, and Moon line up? A. Earth, Moon, Sun B.

What does an octopus have to do with why atoms bond with other atoms?

If there are 50 grams of U-238 on day zero of radioactive decay, how much will there be after 4.5 billion years

6. A particle of mass is released from the position A of a semi-sphere and moves frictionless on its inner surface as shown in the figure. i) Plot the force - cos diagram.

Is momentum conserved in the collision?

Which of the following has more inertia: (a) a rubber ball and a stone of the same size? (b) a bicycle and a train? (c) a five-rupees coin and a one-rupee coin?

In a laboratory, you determine that the density of a certain solid is 5.23*10-6kg/mm3. Convert this density into kilograms per cubic meters.

List the solar objects in correct order from the Sun. Venus Earth Mercury Saturn Neptune Mars Jupiter Asteroid Belt The Sun Uranus

The power exerted by a muscle is the product of the force exerted and the velocity of contraction. The area of which of these shaded regions represents the power exerted while a weight is lifted at maximum speed?