Answer:
500 [J].
Explanation:
1) the rule is: W=E₂-E₁, where W - required work, E₂ - energy after lifting, E₁ - energy before lifting;
2) energy: E=mgh, where m - mass, g≈10 [N/kg], h - height;
3) then the required work:
W=mgh₂-mgh₁=m*g*(h₂-h₁), where (h₂-h₁)=10 [m.]
finally, W=5*10*10=500 [J].
