A probe sent to the surface of Mars uncovers a pure platinum disc inscribed with the message, "We'll be right back" (in Martian, of course!). The disc is 3 inches thick and 0.8 meters in diameter. The density of platinum is 21,450 kg/m^3. What is the mass of the platinum disc in pounds (lbm)?

The Martian acceleration due to gravity is 3.61 m/s^2 while Earth's gravitational constant is 32.2 ft/s^2. What is the Earth weight of the disc in Newtons?

Question

A probe sent to the surface of Mars uncovers a pure platinum disc inscribed with the message, "We'll be right back" (in Martian, of course!). The disc is 3 inches thick and 0.8 meters in diameter. The density of platinum is 21,450 kg/m^3. What is the mass of the platinum disc in pounds (lbm)? 


The Martian acceleration due to gravity is 3.61 m/s^2 while Earth's gravitational constant is 32.2 ft/s^2. What is the Earth weight of the disc in Newtons?

anonymous · Answer

first convert everything into meters

then determine the volume of the disk
area of circle= pi/4*d^2

volume of disk= area*thickness

then multiply by density to determine mass of the disk

anonymous · Answer

now when determining weight you can just ignore the gravity on mars 

convert the gravity constant given to SI units, 

 
then multiply the mass (in kg) by the gravity constant of earth( in m/s^2) to determine the weight of the disk on earth (in newtons)