Problem 62PE

Unreasonable Results

Squids have been reported to jump from the ocean and travel 30.0 m (measured horizontally) before re-entering the water. (a) Calculate the initial speed of the squid if it leaves the water at an angle of 20.0º , assuming negligible lift from the air and negligible air resistance. (b) The squid propels itself by squirting water. What fraction of its mass would it have to eject in order to achieve the speed found in the previous part? The water is ejected at 12.0 m/s ; gravitational force and friction are neglected. (c) What is unreasonable about the results? (d) Which premise is unreasonable, or which premises are inconsistent?

Solution 62 PE

a.)

Step 1 of 4

The initial speed of the squid can be calculated by using an expression for the range of a projectile which relates the initial speed with the range (horizontal distance ) .

Where, R = Range of the projectile in m = 30.0 m

vo= initial speed in m/s

g = acceleration due to gravity = 9.8 m/s2

= angle of projection = 20.0o

Solving forgives,

Substituting 9.8 m/s2 for g, 30.0 m for R and 20.0o for

=

=

=

= 21.39 m/s

Therefore, the initial speed of the squid if it leaves the water at angle of 20o is 21.39 m/s.

b.)