Question

A squid weighing 1.5 kg (excluding water) accelerates by 20 m / s by ejecting 0.15 kg of water. Determine the force acting on the squid and the corresponding acceleration of the ejected water.

Answer 1

According to Newton's second law:

$$F=m_sa_s=1.5·20=30\text{ N}.$$

According to Newton's third law, the same force acts on the water. Then the acceleration of water will be

$$a=F/m_w=30/0.15=200\text{ m/s}^2.$$