Question

O masina cu masa de 800 kg ruleaza cu viteza de 72 km/h.Ce enegie cinetica poseda?​

Answer 1

$v=72 \frac{km}{h} =\frac{72*1000}{3600} =20\frac{m}{s} \\E_{c} =\frac{mv^{2} }{2}\\E_{c}=\frac{800*20^{2} }{2} \\E_{c} =160000J$

Answer 2

Răspuns:

160000 J = 160 kJ

Explicație:

Ec = mv²/2

v = 72km/h = 72000m/3600s = 20 m/s

Ec = 800kg×(400m²/s²)/2 = 160000 J = 160 kJ

Obs.

1 J = kg×m²/s²