Mass And Weight
Overview
Step on a bathroom scale on Earth, then imagine doing the same on the Moon: the number would drop to about a sixth, yet you would still be made of exactly the same amount of stuff. That puzzle is the heart of this topic. Mass and weight feel like the same thing in everyday life, but in physics they are completely different quantities with different units.
Here you will learn to separate the two cleanly, define gravitational field strength, and use the equation that links weight to mass. By the end you will be able to calculate the weight of any object, explain why your mass never changes while your weight depends on where you are, and compare masses using a simple balance.
Objectives
- State that mass is a measure of the quantity of matter in an object at rest relative to the observer
- State that weight is a gravitational force on an object that has mass
- Define gravitational field strength as force per unit mass; recall and use the equation W g = m and know that this is equivalent to the acceleration of free fall
- Know that weights (and masses) may be compared using a balance
- [Supplement] Describe, and use the concept of, weight as the effect of a gravitational field on a mass
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Lesson Evaluation
Congratulations on completing the lesson on Mass And Weight. Now that youve explored the key concepts and ideas, its time to put your knowledge to the test. This section offers a variety of practice questions designed to reinforce your understanding and help you gauge your grasp of the material.
You will encounter a mix of question types, including multiple-choice questions, short answer questions, and essay questions. Each question is thoughtfully crafted to assess different aspects of your knowledge and critical thinking skills.
Use this evaluation section as an opportunity to reinforce your understanding of the topic and to identify any areas where you may need additional study. Don't be discouraged by any challenges you encounter; instead, view them as opportunities for growth and improvement.
- Which statement about mass is correct? A. it is a force measured in newtons B. it changes on the Moon C. it is the quantity of matter, measured in kilograms D. it equals weight Answer: C
- An object of mass 5 kg is on Earth where g = 9.8 N/kg. Its weight is: A. 5 N B. 0.51 N C. 49 N D. 9.8 N Answer: C
- Gravitational field strength is defined as: A. mass per unit force B. force per unit mass C. weight times mass D. mass times acceleration Answer: B
- A 10 kg mass is moved from Earth to the Moon. Which quantity stays the same? A. weight B. gravitational field strength C. mass D. the force of gravity on it Answer: C
- The unit of gravitational field strength is: A. N B. kg C. N/kg D. m/s Answer: C
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