please again buat semuanya! deadline!! please dua2 nya kawan-kawan.

Nomor 3
k = mg / Δx
   = (2 kg)(10 m/s²) / (0,05 m) = 400 N/m

Nomor 4
EP = 1/2 kΔx²
Δx = √(2EP / k)
     = √[2(0,9 J) / (2000 N/m)] = 0,03 m = 3 cm

F = kΔx
   = (2000 N/m)(0,03 m) = 60 N