Question

A toy gun uses a spring to project a 4.6-g soft rubber sphere horizontally. The spring constant is 8.0 N/m, the barrel of the gun is 14 cm long, and a constant frictional force of 0.031 N exists between barrel and projectile. With what speed does the projectile leave the barrel if the spring was compressed 6.5 cm for this launch? (Assume the projectile is in contact with the barrel for the full 14 cm.)

m/s

Answer 1

initial energy = final energy

0.5*K*x^2 = f*.14 +0.5*m*v^2

0.5*8*.065^2 = .031*.14 +0.5*.0046*v^2

v = 2.336 m/sec