Final answer:
To stop the salmon, the fishing line needs to exert a force of -1,335.9375 N in the opposite direction of motion.
Step-by-step explanation:
In order to stop the 19 kg salmon swimming at 4.5 m/s in a distance of 0.12 m, we can use the equation: force = mass × acceleration. Since the salmon is already moving, we need to calculate the deceleration it experiences. The initial velocity is 4.5 m/s, the final velocity is 0 m/s (as it comes to a stop), and the distance traveled is 0.12 m.
Using the equation of motion v² = u² + 2as, we can rearrange it to solve for acceleration: a = (v² - u²) / (2s). Plugging in the given values, we get: a = (0 - (4.5)²) / (2 × 0.12). Solving this equation gives us a deceleration of -70.3125 m/s².
Finally, we can determine the force exerted by the fishing line using the equation force = mass × acceleration. Plugging in the mass of the salmon (19 kg) and the acceleration (-70.3125 m/s²), we get a force of -1,335.9375 N. The negative sign indicates that the force is in the opposite direction of motion, which is what we expect when stopping the salmon.
Learn more about force needed to stop a moving object