Question

Densitatea unui corp scade prin incalzire cu 20%.Cu cat la suta a crescut volumul ?

Answer 1

q'=q-20/100*q
q'=80/100*q
q'=5/4*q
V'=$\frac{m}{q'}$=$\frac{m}{ \frac{5}{4}q }$=$\frac{5}{4}$V
$\frac{p}{100}$V=V'-V
$\frac{p}{100}$=$\frac{5}{4}$-1=$\frac{25}{100}$=25%

Answer 2

- la temperatura t0 vom avea m=ρ0·V0; la t1, t1>t0 avem m=ρ1·V1; 
ρ1=ρ0-20/100*ρ0=80/100*ρ0;
ρ0·V0=ρ1·V1 ⇒ ρ0·V0=((80/100)*ρ0)*V1 ⇒ V1=100/80*V0=1,25V0;
V1-V0=1,25V0-V0=0,25V0=25%V0