Respuesta :
Complete Question:
As a fish jumps vertically out of the water, assume that only two significant forces act on it: an upward force F exerted by the tail fin and the downward force due to gravity. A record Chinook salmon has a length of 1.50 m and a mass of 48.0 kg. If this fish is moving upward at 3.00 m/s as its head first breaks the surface and has an upward speed of 6.30 m/s after two-thirds of its length has left the surface, assume constant acceleration and determine the following. (a) the salmon's acceleration m/s2 upward (b) the magnitude of the force F during this interval N
Answer:
(a) acceleration = 15.3 msâťÂ˛
(b) Magnitude of net force = 734.4 N
Magnitude of upward force exerted by tail fin = 1204.8 N
Explanation:
Mass of the salmon fish = 48 kg
Length of the Salmon Fish = 1.5 m
g = 9.8 msâťÂ˛
(a) salmon's acceleration during the time interval N:
Downward Force on the fish is equal to the Force due to gravity and is given as:
Fâ = mg
= 48 * 9.8
= 470.4 N
The direction of movement of the fish is upward and the acceleration is constant. We are given two different velocities of fish at two different instances.
- When the head breaks out of the water surface first:
Initial velocity = vâ = 3 m/s
- When two third of its body length is out = d = 1 m
 Final Velocity = vâ = 6.3 m/s
Using the third equation of motion:
2*a*d = vâ² - vâ²
a = (6.3² - 3²)/2*1
a = 15.3 msâťÂ˛
(b) magnitude of force F during this interval N = ?
We are assuming that F is the net force consisting of both the upward and the downward force.
According to Newton's 2nd law of motion, Force is given as:
F = ma
F = 48 kg * 15.3
F = 734.4 N
Magnitude of upward Force = Fâ
Force Fâ exerted by the tail fin of the fish is given by
F = Fâ - Fâ
That is the net force is the sum of the upward and downward forces acting on the fish body. Fâ is positive because it is in upward direction and Fâ is negative because it is in downward direction. F which is the net force here is positive as Fâ > Fâ.
=> Â Fâ = F + Fâ
Fâ = 734.4 + 470.4
Fâ = 1204.8 N