An iron rod is 1.58 m long at 0°c. what must
be the length of a brass rod at 0°c if the
difference between the lengths of the two rods
is to remain the same at all temperatures.
linear expansivity of iron = 1.2 x 10-5 k-1
linear expansivity of brass = 1.9 x 10-5 k-1.

this urgent

does anyone know or what?

jupiter is the largest planet in our solar system, having a mass and radius that are respectively, 318 and 11.2 times that of earth. suppose that an object falls from rest near the surface of each planet and that the acceleration due to gravity remains constant during the fall. each object falls the same distance before striking the ground. determine the ratio of the time of fall on jupiter to that on earth.

3. dark matter

empty space could also be a simple vacuum