It takes force of 15 N to stretch an ideal spring of negligible mass 3.0 cm. The spring is placed on a frictionless horizontal tabletop with one end fixed. A small 50-g metal ball is placed at the free end.
By how much should the spring be compressed to set the ball in motion horizontally at a speed of
4.5 m/s?
A) 21 cm
B) 4.5 cm
C) 2.1 cm
D) 9.0 cm
E) 4.2 cm

Aliquid is an answer i hope this

Answer: a charge of -1.0  × 10⁻⁴ c must be placed  at x = 26 m.the sign of the charge will be the same sign as the  -4.0  µc charge.======electricstatic force between two point charges  is given by    where k is coulomb's constant,  8.99×10⁹  n·m²/c², q₁ and q₂ are the point charges, and r is the distance between the two point charges.assign positive to q₁let q₁ =  6.0 µc, q₂ = -4.0  µc, q₀ represent the charge at the origin, and q₃ represent this new charge to place.the charge at the origin q₀ would experience the following force f₀₁ from q₁, with r = 6.0 m (note that 1  µc = 10⁻⁶ c)    the force from q₂    the force from q₃    the net force on the origin charge, q₀, has to be zero for no electrostatic forcehaving an equation where k and q₀ can be divided out of the equation will allow us to solve for q₃    isolating:     a charge of -1.0  × 10⁻⁴ c must be placed  at x = 26 m.the sign of the charge will be the same as the  -4.0  µc charge

B. elliptical. as in oval. 0 (==