A hollow spherical ball is made of an iron material of weight 5.25grm/m³. The ball has radius of 7 m and thickness of 200 cm. Find the weight of the ball?
Answer & explanation
Correct answer: option 2
200 cm = 2 m
R = 7 m, r = 7 - 2 = 5 m
Volume of ball = \(\frac{4}{3}\) \(\pi \)(R3 - r3)
= \(\frac{4}{3}\) \(\pi \) ((7)3 - (5)3)
= \(\frac{4\;×\;22}{3\;×\;7}\) ×(218)
The weight of the spherical ball is = volume× 5.25g/m3
= \(\frac{4\;×\;22}{3\;×\;7}\) ×(218) × \(\frac{21}{4}\) = 4746 g or 4.75 kg