no. 14 gimana ya... pake cara yaa

Tekanan

gaya berat (F) = m x g
F = 3 x 10
F = 30 N

luas bidang tekan (A) = l x t
A = 30 x 40
A = 1200 cm^2
A = 0,12 m^2

tekanan (P) = F/A
P = 30 : 0,12
P = 250 N/m^2 (C).

*semoga membantu. sukses selalu ^_^