Squid usually move by using their fins, but they can utilize a form of \"jet pro

Question

Squid usually move by using their fins, but they can utilize a form of "jet propulsion," ejecting water at high speed to rocket them backward, as shown in the figure. A 4.0kg squid can slowly draw in and then quickly eject 0.30kg of water. The water is ejected in 0.10s at a speed of 10m/s. This gives the squid a quick burst of speed to evade predators or catch prey.

A) What is the squid's approximate acceleration in g?

B) This form of locomotion is speedy, but is it efficient? The energy that the squid expends goes two places: the kinetic energy of the squid and the kinetic energy of the water. Think about how to define "what you get" and "what you had to pay"; then calculate an efficiency for this particular form of locomotion. (You can ignore biomechanical efficiency for this problem.)

Explanation / Answer

a) Conserving momentum,

4v-0.3*10=0

v=0.75m/s

b)accleration=v/t=0.765g

c)F=p/t=mv/t=0.3*10/0.1=30N

d)efficiency=0.5*4*0.752/(0.5*4*0.752+0.5*0.3*102)=6.98%

Clearly, this is very inefficient.

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