Question

有一块重3N的木块,把它放在水中静止时,2/5的体积浮出水面.

Answer 1

(1)受到浮力即重力,为3N

(2)ρ(H2O)*g* (3/5)V(木)=ρ(木)*g*V(木)

得 ρ(木)=3/5ρ(H2O)

5/3ρ(木)=ρ(H2O)

(3)F = ρ(H2O)*g*V(木)-ρ(木)*g*V(木)

= 2/5ρ(H2O)*g* V(木)

= 2/3ρ(木)*g*V(木)

= (2/3)*3N

= 2N