Question

O macara cu puterea 8, 82 kW a ridicat un corp cu masa 4, 5 t la o inaltime de 8 m.In cat timp a facut aceasta lucrare?

Se da g=9, 8 N/kg.

Answer 1

P=8,82 kW=8820 W=8820 J/s
m=4,5 t=4500 kg
h=8m

F=m*g=4500*9,8=44100 N
L=F*h=44100*8=352800 N*m=352800 J

P=L/t=, deci
t=L/P=352800:8820=40 s