A squid ejects a bolus of water in order to escape a predator. The squid has a mass of 0.4 kg with its water cavity empty, and needs to escape with a speed of at least 0.8 m/s. If the ejected water has a mass of 0.1 kg, how fast must it be ejected in order for the squid to escape?
A)4.0 m/s
B)3.2 m/s
C)1.6 m/s
D)0.8 m/s

Question

Quizplus · Accepted Answer

Using conservation of momentum, the momentum of the squid and water system before and after ejection must be equal. The initial momentum is zero, so 0.4 kg * 0.8 m/s = 0.1 kg * v. Solving for v gives v = 3.2 m/s.

A Squid Ejects a Bolus of Water in Order to Escape