![]() ![]() mass Mass is an intrinsic property that measures the quantity of matter in an object. They may have prior knowledge.ġ6 Weight vs. Give students a moment to answer the question. How is weight different from mass? Reinforce this idea: weight IS the force of gravity. Weight is the force of gravity acting on objects with mass. People can also apply forces by pushing or pulling on objects.ġ3 Units of force Quantitative: Force is measured in newtons.Ī useful reference: one newton of force is about equal to the weight of a stick of butter pressing down on your hand as you hold it.ġ4 Units of force When students learn Newton’s second law, F = ma, it will provide a useful tool for remembering the definition of a Newton: 1 N = (1 kg) (1 m/s2). Can you give some examples of forces? Examples of forces: weight friction tension from rope force from a spring electric force Students may also mention atomic forces, magnetic forces, gravity, air resistance, buoyancy, etc. Can you give some examples of forces? Give the students a couple minutes to name some forces they have heard about.ġ2 Types of forces The concept of force: A force is a push or a pull.įorces can cause an object to change its motion. if possible, pass around a few 1 kg masses so that students can develop a feel for this unit.ġ0 What is force? The concept of force: A force is a push or a pull.ġ1 What is force? The concept of force: A force is a push or a pull.įorces can cause an object to change its motion. These next two slides review the concept of mass, which was introduced in Chapter 2.ĩ Measuring mass The SI unit for mass is the kilogram. With your hand out the window of a moving car, you feel the mass in the air pushing against you. This can be likened to the difference in biology between the study of taxonomy and science of genetics.Ĩ What is mass? All matter has mass and takes up space.Ī solid rock has mass. In chapter 4 they will begin the work of learning how to explain WHY objects move they way they do. He based his laws of motion on two key concepts: mass force Point out to students that in chapters 2 and 3 they learned how to describe motion (using physics vocabulary like displacement, velocity, and acceleration). Isaac Newton was the first person to explain WHY objects move the way they do. The value of g varies over the surface of the Earth, from 9.78 N/kg to 9.83 N/kg, depending on latitude. The value for g here is given to two significant digits. This slide lists key vocabulary for the lesson.Ħ Equations Weight is mass multiplied by the strength of gravity.Īt Earth’ s surface the strength of gravity is 9.8 newtons per kilogram. They will be repeated at the end of the lesson, followed by the answer.ĥ Physics terms mass force weight newtons pounds These assessments are keyed to the second objective: calculate weight from mass or mass from weight. What is this weight in newtons? What is this person’s mass in kilograms? A 10 kg dumbbell resting on a table is partly supported by a spring that pulls upward with a force of 50 N. It will be repeated at the end of the lesson, followed by the answer.Ĥ Assessment What is the weight of this dumbbell, in newtons?Ī person weighs 150 lbs. This first assessment is keyed to the first objective: Explain the difference between weight and mass. Your mass increases and your weight decreases. Your mass decreases and your weight stays the same. Your mass stays the same and your weight decreases. The lesson objectives describe what the student should know or be able to do upon completion of the lesson.ģ Assessment If you take a trip from Earth to the Moon, which statement below is correct? Your mass and weight both decrease. The force of gravity is related to but distinct from the mass of an object.Ģ Objectives Explain the difference between weight and mass.Ĭalculate weight from mass or mass from weight. This lesson reinforces the fact that weight IS the force due to gravity. Students sometimes consider the force due to gravity and weight to be two different forces. This idea is made more quantitative with units of newtons and pounds. 1 Force and weight The concept of force is simply a push or pull.
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