81.4k views
4 votes
A uniform sphere of m = 0.85 kg and radius r = 4.2 cm:

a) Compute its volume
b) Determine its density
c) Calculate its gravitational potential energy
d) Find its moment of inertia

User Heinrisch
by
8.6k points

1 Answer

4 votes

Final answer:

a) The volume of the sphere is 310 cm^3. b) The density of the sphere is approximately 0.0027 kg/cm^3. c) The gravitational potential energy of the sphere is 0.35 J. d) The moment of inertia of the sphere is approximately 0.006 J.

Step-by-step explanation:

a) The volume of a sphere is given by the formula V = 4/3πr^3, where r is the radius. Plugging in the given radius of 4.2 cm, we can calculate the volume:

V = 4/3 * 3.14 * (4.2 cm)^3 = 310 cm^3

b) Density is defined as mass divided by volume. Given that the mass is 0.85 kg and the volume is 310 cm^3, we can calculate the density as follows:

Density = mass / volume = 0.85 kg / 310 cm^3 = 0.0027 kg/cm^3

c) The gravitational potential energy of an object near the Earth's surface is given by the formula PE = mgh, where m is the mass, g is the acceleration due to gravity (9.8 m/s^2), and h is the height. Since the sphere is uniform, we can take the height as the radius. Plugging in the given values:

PE = 0.85 kg * 9.8 m/s^2 * (4.2 cm / 100) = 0.35 J

d) The moment of inertia of a solid sphere is given by the formula I = (2/5)mr^2, where m is the mass and r is the radius. Plugging in the given values:

I = (2/5) * 0.85 kg * (4.2 cm / 100)^2 = 0.006 J

User Ron Wertlen
by
8.6k points