Question

dau coroana!! e pana maine.​

Answer 1

Răspuns:

1. R² = F₁² + F₂² + 2F₁F₂cos60

R² = 100 + 900 + 2*10*30*1/2

R² = 1300

R = $\sqrt{1300}$ = 10$\sqrt{13}$ N varianta a.

Explicație:

2. 45km/h = 45 * 1000m/ 3600s = 12.5 m/s varianta c.

3.

d = 15 km = 15 000 m

t = 25 * 60 = 1500 s

v = d/t = 15000/1500 = 10 m/s

Pt. tren

v₁= 2v = 20m/s

t₁ = 10*60 = 600s

d₁ = v₁ * t₁ = 20 m/s * 600s = 12 000 m = 12 km varianta b.