Question

Please help on this one?

Answer 1

Answer:

(C) The speed is the spring passing the neutral point of the spring is 0.32m/s

Explanation:

We use the law of energy conservation. The potential energy stored in the spring is transformed into kinetic energy of the mass,  attaining its maximum at the neutral point of the spring (with the spring potential energy being zero there) - that is exactly the point at which we are asked to determine the velocity.

The potential energy stored in the spring compressed by 0.1m is

$U = \frac{1}{2}kl^2=\frac{1}{2}20\frac{N}{m}0.1^2m^2=0.1J$

Neglecting friction, this amount of energy will become the kinetic energy at its maximum:

$U = \frac{1}{2}mv^2\implies |v|=\sqrt{\frac{2U}{m}}=\sqrt{\frac{2\cdot0.1kg\frac{m^2}{s^2}}{2kg}}=0.32 \frac{m}{s}$

The speed is the spring passing the neutral point of the spring is 0.32m/s