Really clueless = Minimum Mass Tension Force Question

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SUMMARY

The discussion revolves around calculating the minimum mass of a fish that a fisherman yanks straight up with an acceleration of 2 m/s², using a fishing line with a test value of 50 pounds. The correct mass of the fish is determined to be 18.9 kg. Participants clarify that the acceleration due to gravity (9.81 m/s²) must be added to the upward acceleration when calculating the force exerted on the fish, leading to the formula F_max = m_fish * (2 + 9.81). The misunderstanding regarding the conversion of pounds to kilograms is also addressed, with the correct conversion being approximately 22.68 kg for 50 pounds.

PREREQUISITES
  • Understanding of Newton's second law of motion (F = ma)
  • Knowledge of gravitational acceleration (9.81 m/s²)
  • Ability to convert units (pounds to kilograms)
  • Familiarity with basic physics concepts related to tension and forces
NEXT STEPS
  • Study the application of Newton's second law in various scenarios
  • Learn about tension in strings and ropes in physics
  • Explore unit conversion techniques, especially between imperial and metric systems
  • Investigate real-world applications of forces in sports, such as tug-of-war
USEFUL FOR

Students studying physics, particularly those tackling problems involving forces and motion, as well as educators looking for practical examples to illustrate these concepts.

Pandaanli
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Homework Statement



A fisherman yanks a fish straight up out of the water with an acceleration of 2m/s^2 using very light fishing line that has a "test value" of 50 pounds. the fisherman, loses the fish as the line snaps.
What is the minimum mass of the fish?


The answer given is mass=18.9kg

No additional information is given, and it's just a question by it self, no other values attached.

Homework Equations




The Attempt at a Solution



I converted pounds into kg since they asked for mass as solution
They asked for 3 Sig Figs, so 50 pounds =22.72kg
I'm assuming the acceleration is 2m/s^2 all the way
but I'm not sure how that get me the 18.9 kg answer



I'm seriously clueless with this question, about both the concept and how the answer is gotten. Been trying to figure it out for at least 3 hours, really need your help Q__Q
Please and Thank you!
 
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Pandaanli said:
I'm assuming the acceleration is 2m/s^2 all the way
but I'm not sure how that get me the 18.9 kg answer
When a fisherman yanks a fish straight up out of the water, the acceleration of 2m/s^2 should be added to gravity acceleration (9.81m/s^2).

regards
 
Bartek said:
When a fisherman yanks a fish straight up out of the water, the acceleration of 2m/s^2 should be added to gravity acceleration (9.81m/s^2).

regards


Thanks for the reply, Bartek!

I plugged the new acceleration in, and played around with different equations
I've got many answers, but none that's 18.9kg
F= ma
= (22.72)(11.8)
= 222.656 N
How should I continue next?
 
Pandaanli said:
Thanks for the reply, Bartek!

I plugged the new acceleration in, and played around with different equations
I've got many answers, but none that's 18.9kg
F= ma
= (22.72)(11.8)
= 222.656 N
How should I continue next?
No! When line was tested a=g. So Fmax is (22.72)*9.81, not 11.81 (during test the mass of 50 pounds hanging motionless). F_max is a maximum line tension.

When fisherman yanks a fish, this Fmax should be equal to (m_fish)*(2+9.81). You can calculate m_fish.

regards

ps.
50 pounds is equal to 22,6796185 kg, How did you got 22.72?
 
Last edited:
Bartek said:
No! When line was tested a=g. So Fmax is (22.72)*9.81, not 11.81 (during test the mass of 50 pounds hanging motionless). F_max is a maximum line tension.

When fisherman yanks a fish, this Fmax should be equal to (m_fish)*(2+9.81). You can calculate m_fish.

regards

ps.
50 pounds is equal to 22,6796185 kg, How did you got 22.72?

Hahah I have no idea how did I get 22.72, probably 1kg = 2.2 lbs

Thank you so much ♥ Finally it's solved~! :D


BTW, I have another tensions concept question

Two tug-of-war teams are at opposite ends of rope. Newton's third law says that the force exerted by team A will equal the force that team B exerts, how can either team win the tug-of-war?

Does the player's mass and friction play a role?
 
Pandaanli said:
how can either team win the tug-of-war?
Imagine both teams and a rope as a one rigid body. What forces exert this "body" horizontally? When it will be moved?
 
Bartek said:
Imagine both teams and a rope as a one rigid body. What forces exert this "body" horizontally? When it will be moved?

Friction force exerts on the body horizontally, it'd move when the forces on one side is greater than the other? But what's going to trigger that unbalanced force?
 
Pandaanli said:
Friction force exerts on the body horizontally, it'd move when the forces on one side is greater than the other?
Yes.
Pandaanli said:
But what's going to trigger that unbalanced force?
muscles :biggrin:. Both teams are pushing the ground... so, ground pushing the teams. Stronger win.
 
Bartek said:
Yes.
muscles :biggrin:. Both teams are pushing the ground... so, ground pushing the teams. Stronger win.


Thank you thank you ♥
I can finally hand in my work and sleep in peace :D



PS, are you teaching physics? or just doing for fun?
 
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