Question

what does it mean (in physics) to say that a quantity is conserved?
it means the total amount is zero.
it means its being saved up.
it means that the quantity is not being used.
it means the total amount never changes.
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1. - / 1 points

your textbook is transported from earth to the moon. which of the following statements is true?
the mass of your textbook will change but the weight of your textbook will remain the same.
both the mass & the weight of your textbook will change.
the mass of your textbook will remain the same but the weight of your textbook will change.
both the mass & the weight of your textbook will remain the same.

Explanation:

• For the first question: In physics, when a quantity is conserved, it means that the total amount of that quantity in an isolated system never changes. It has nothing to do with the quantity being zero (e.g., energy can be conserved but non - zero), being saved up in a non - physical sense (like money in a bank), or not being used.
• For the second question: Mass is a measure of the amount of matter in an object and is an intrinsic property. It does not depend on the location. Weight is given by \(W = mg\), where \(g\) is the acceleration due to gravity. The acceleration due to gravity on the Moon (\(g_{moon}\approx1.62\ m/s^{2}\)) is different from that on Earth (\(g_{earth}\approx9.8\ m/s^{2}\)). So, when the textbook is moved from Earth to the Moon, its mass \(m\) remains the same, but its weight \(W\) (since \(W = mg\) and \(g\) changes) will change.

Answer:

• First question: It means the total amount never changes.
• Second question: The mass of your textbook will remain the same but the weight of your textbook will change.