Question

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

Answer 1

P=8,82 kw--->P= 8820W
m=4,5T--->m= 4500kg
h=8m
t=?
P=$\frac{L}{t}$
h(inaltimea), in cazul nostru este distanta.
L=F*h
G=m*g =>G= 4500kg*9,8N/kg= 44.100N
L=44.100N*8 m=352.800J
P= $\frac{L}{t} \ \textless \ =\ \textgreater \ t= \frac{L}{P} \ \textless \ =\ \textgreater \ t= \frac{352.800J}{8820W} =40$
t=40s