What is the radius of the circular plate of thickness 1 cm made by melting a…
2023
What is the radius of the circular plate of thickness 1 cm made by melting a sphere of radius 3 cm?
- A.
6 cm
- B.
5 cm
- C.
4 cm
- D.
7 cm
Attempted by 5 students.
Show answer & explanation
Correct answer: A
Step 1: Compute the sphere's volume. Volume of sphere = (4/3)πr^3 = (4/3)π·3^3 = (4/3)π·27 = 36π cubic cm.
Step 2: Express the plate's volume. The plate is a cylinder of thickness 1 cm, so Volume of plate = π·R^2·h with h = 1 cm, hence π·R^2·1 = π·R^2.
Step 3: Equate volumes and solve for R.
π·R^2 = 36π
R^2 = 36 ⇒ R = 6 cm
Answer: 6 cm.