When preparing a toy pistol for a shot, a spring with a stiffness of 800 N / m was squeezed by 5 cm.

When preparing a toy pistol for a shot, a spring with a stiffness of 800 N / m was squeezed by 5 cm. What speed does a ball weighing 20 g acquire when fired in a horizontal direction

Potential energy of a compressed spring:

Ep = k x ^ 2/2,

where k is the coefficient of spring stiffness, k = 800 N / m;

x is the magnitude of the compression deformation, x = 5 cm = 0.05 m.

When fired horizontally, the potential energy of the spring is converted into kinetic energy of the bullet:

Ep = Ec = m V ^ 2/2,

where m is the mass of the bullet, m = 20 g = 0.02 kg; V – bullet speed, m / s.

We get:

k x ^ 2/2 = m V ^ 2/2.

So the bullet speed is:

V = (k x ^ 2 / m) 1/2 = (800 × 0.05 ^ 2 / 0.02) 1/2 = 10.0 m / s.

Answer: 10.0 m / s.