What is the Relationship Between Force and Weight?

Thread starter Northern Cardinal
Start date Oct 31, 2020
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Force Weight

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SUMMARY

The discussion clarifies the distinction between force and weight, emphasizing that weight is a force measured in Newtons, while mass is measured in kilograms. The user initially attempted to calculate the ratio of force to weight using incorrect values, leading to confusion. The correct understanding is that weight is derived from mass multiplied by the acceleration due to gravity, specifically using the formula Weight = Mass × Gravity (where gravity is approximately 9.81 m/s²). The user successfully resolved their misunderstanding by recognizing this fundamental principle.

PREREQUISITES

Understanding of Newton's Second Law of Motion
Basic knowledge of units of measurement (Newtons and kilograms)
Familiarity with the concept of gravitational acceleration
Ability to perform basic mathematical calculations

NEXT STEPS

Study the relationship between mass, weight, and gravitational force using the formula Weight = Mass × Gravity
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Students studying physics, educators teaching basic mechanics, and anyone interested in understanding the fundamental principles of force and weight relationships.

Oct 31, 2020

Northern Cardinal

Homework Statement: I need help figuring out c.

a) A 15.0-kg child is riding a playground merry-go-round that is rotating at 45.0 rpm. What centripetal force must she exert to stay on if she is 1.50 m from its center?
Correct answer: 499.649 N
b) What centripetal force does she need to stay on an amusement park merry-go-round that rotates at 3.00 rpm if she is 7.10 m from its center?
Correct answer: 10.511 N
c) Compare each force with her weight.

Relevant Equations: force from part (a) / weight = _______
force from part (b) / weight = _______

So here's what I've tried:

force from part (a) / weight = 499.649N / 15kg = 33.310
force from part (b) / weight = 10.511N / 15kg = 0.701

Apparently this wasn't correct. What am I doing wrong? I feel like I'm missing the obvious.

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Oct 31, 2020

gneill

Mentor

Mass is stated in kg. That's not weight. Weight is a force in Newtons.

Oct 31, 2020

Northern Cardinal

Thanks! I was able to figure out the correct answer.

Oct 31, 2020

gneill

Mentor

Excellent!

Thread 'Magnitude of buoyant force in fluids of different densities'

The book claims the answer is that all the magnitudes are the same because "the gravitational force on the penguin is the same". I'm having trouble understanding this. I thought the buoyant force was equal to the weight of the fluid displaced. Weight depends on mass which depends on density. Therefore, due to the differing densities the buoyant force will be different in each case? Is this incorrect?

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