[填空题]
At the surface of a h 63;kxrhgeuob; t/29* h/ad myb4xh acertain 9p f ce2,kpr/(8bbj erp+uye*planet, the gravitational acceleration g has a magnitude of 1pj8+brep c9b, upekr* e(f/2y 2 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? $W_{Earth}$ $W_{planet}$
