A section of cuboid wood is 1.2 meters long. If you want to cut it short by 2 cm, its volume will be reduced by 40 cubic cm

A section of cuboid wood is 1.2 meters long. If you want to cut it short by 2 cm, its volume will be reduced by 40 cubic cm

1.2 m = 120 cm, 40 △ 2 × 120 = 20 × 120 = 2400 (cubic cm); a: the original volume of this section of wood is 2400 cubic cm

The density of silver is 10.5 times 10 cubic kg / m
The mass of a silver medal is 160g
If a bronze medal is the same size as it
And the density of copper is 8.9 times 10 cubic kg / m
Ask for the quality of this bronze medal

ρ silver = 10.5 * 10 & # 179; kg / M & # 179; = 10.5g/cm & # 179;
Mgag = 160g
V Ag = m / ρ = 160g / 10.5G = 15.24cm & # 179;
V Cu = V Ag = 15.24cm;
M copper = ρ v = 15.24cm & #179; * 8.9 * g = 135.636g

If m ^ 2-2m = 1, then the value of 2m ^ 2-4m + 2010

m²-2m=1
2m^2-4m+2010
=2(m²-2m)+2010
=2+2010
=2012