4.
a)OA-modulul vitezei initiale a mobilului 3
OB-modulul vitezii initiale a mobilului 2
OC-modulul vitezii finale a mobilului 3
b)a=Δv/Δt=(v-v0)/t, Δt e in general t-t0, dar in grafie t0=0 pentru toti
Din grafic:
Primul corp:
v01=0m/s
v1=10m/s
t=6s
a=[tex]\displaystyle \frac{0-10}{6}=-\frac 53[/tex] m/s²
Al doilea corp:
v02=3m/s
v2=10m/s
t2=6s
a=[tex]\displaystyle \frac{10-3}{6}=\frac 76[/tex] m/s²²
Al treielea corp:
v03=10m/s
v3=0m/s
t=10s
a=[tex]\displaystyle \frac {10-0}{10}=1[/tex] m/s²
c)v(t)=v0+a*t
d(t)=v0*t+at²/2
Inlocuim v0 si a pentru cele trei corpuri:
1)v1(t)=[tex]\displaystyle -\frac 53t[/tex] m/s
d1(t)=[tex]\displaystyle -\frac {5t^2}6[/tex]
2)v2(t)=[tex]\displaystyle 3+\frac 76t[/tex]
d2(t)=[tex]\displaystyle 3t+\frac{7t^2}{12}[/tex]
3)v3(t)=[tex]\displaystyle 10+t[/tex]
d3(t)=[tex]\displaystyle 10t+\frac{t^2}{2}[/tex]
5.
[tex]\displaystyle \text{Se da:}\\ \\
t=15s\\ \\
v=100\frac ms\\ \\
a=\frac m{s^2}\\ \\
d=?m\\ \\ \\
Formule:\\ \\
a=\frac vt\\ \\ \\
d=\frac {v\times t}2\\ \\ \\
Calcule:\\ \\
a=\frac{100}{15}\approx 6,67\frac m{s^2}\\ \\
d=\frac{100\times 15}{2}=750m[/tex]
6.
[tex]\displaystyle \text{Se da:}\\ \\
v_0=1000\frac ms\\ \\
t=0,001s\\ \\
v=200\frac ms\\ \\
d=?m\\ \\ \\
Formule:\\ \\
d=\frac{v+v_0}{2}\times t\\ \\ \\
Calcule:\\ \\
d=\frac{1000+200}{2}\times 0,001=0,6m[/tex]
