Respuesta :

indrawboy

vf²=vi²+2ad

12²=0+2.a.10

a = 7.2 m/s²

W = m.g

m = W/g = 98/9.8 = 10 kg

∑F=m.a

W-fr=m.a

fr(air friction)=W - m.a

fr = 98 - 10 x 7.2

fr = 98 - 72

fr = 26 N