Question

1.Avem o forta de 1200N care efectueaza un lucru mecanic de 126KJ. Aflati deplasarea.
2.Un copil cu masa de 50kg efectueaza un lucru mecanic de 5,2KJ ducand un sac de 15kg. Afla deplasarea.

Answer 1

$F=1200\: N$

$L=126\:KJ\implies 126\:KJ=126\cdot 1000\:kg=126\,000\:J$

$L=F\cdot d \implies d=\frac{L}{F}$

$d=\frac{L}{F} \implies d=\frac{126\,000\:J}{12000\,N} ^{(1000}=\frac{126\,N\cdot m}{12\,N} =10,5 \,m$

_______________________________________________

$L=5,2\,KJ=5,2\cdot1000\,kg=5200\,J$

$m_1=50\,kg$

$m_2=15\,kg$

$\implies G_1=m_1 \cdot g=50\,kg \cdot10\frac{N}{kg} =500\,N$

$\implies G_2=m_2\cdot g=15\,kg \cdot10\frac{N}{kg} =150\,N$

$\implies F=G_1+G_2=500\,N+150\,N=650\,N$

$L=F\cdot d \implies d=\frac{L}{F}$

$\implies d=\frac{5200\,J}{650\,N} ^{(10}=\frac{520\,N\cdot m}{65\,N} =8\,m$

Answer 2

126KJ=126000J

L=F×d deci d=L/F => d=126000/12000=10,5 m

_____

5,2KJ=5,2×1000=5200J

m1=50kg=>G=m×g=50×10=500N

m2=q5kg=>G=m×g=15×10=150

=>G1+G2=150N+500N=650N

d=L/F=> d=5200J/650N = 8m