[填空题]
At the surface of a certain plaunp3 7 sve) f9gdhh/ic3koi 09net, the gravitational acceleration vk4j8::c8k t+mp2kcqo0acm ig has a magnitude of makq2co +kv 4jp8i:t0:c m8ck 12 m/s$^2$ A 21.0-kg brass ball is transported to this planet. What is (a) the mass of the brass ball on the Earth and on the planet
(b) the weight of the brass ball on the Earth and on the planet? $W_{Earth}$ $W_{planet}$
