When we say that work is done by or against some agent,what do we mean? Name some "agents'>Ħ. How is power different from work or energy?ĥ. Is work being done when a heavy weight is held motionlessoverhead? Explain.Ĥ. Define work as it is used in physical science and givean example of work.ģ. Apply conservation of energy to various physical situations Questions 1. Define the characteristics of conservative and non conservativesystemsħ. State the work energy theorem and define its applications.Ħ. Define potential energy and its variables.ĥ.
Define kinetic energy and its variables.Ĥ. Define the physical concept of work and apply it tovarious situations.ģ. Be sure to read these objectives inthe study guide and refer to them as you study the lesson.įocusing on the learning objectives will help you to study, to understand theimportant concepts and to synthesize.Ĭompare the objectives with the study questions for the lesson to be sure thatyou have the concepts under control. Look for key words and ideas as you read. Here are the objectives for today's lesson.īefore you begin to study the lesson, take a few minutes to read the objectivesand the study questions for this lesson. Find the angular momentum and torque on the mass about O.Lesson 3.4 Text References Spielberg & Anderson 111-118 Find the torque on the block about (a) the origin (b) point A.Ī conical pendulum of mass m and length L is in uniform circular motion with a velocity v (see Fig. These forces are very large such that any other forces ( \(\mathrm \) (see Fig. The linear momentum (or quantity of motion as was called by Newton) of a particle of mass m is a vector quantity defined asĪs discussed previously, when two bodies collide, they exert large forces on one another (during the time of the collision) called impulsive forces. Next, we will discuss and verify the concepts of momentum and impulse, and the law of conservation of momentum. Therefore, it is not necessary to know the exact form of the impulsive forces, which makes the problem easy to analyze. The law of conservation of momentum is especially used in analyzing collisions and is applied immediately before and immediately after the collision. These concepts enable us to analyze problems that involve collisions, as well as many other problems. Thus, new concepts known as momentum and impulse were introduced. Because these forces are complex functions of the collision time, it is difficult to find their exact form and would make it difficult to use Newton’s second law to solve such problems.
To solve collision problems by using Newton’s second law, it is required to know the exact form of the impulsive forces. This force is called an impulsive force, because it acts for a short period of time compared to the whole motion of the objects, and its value is usually large. During the collision, each body exerts a force on the other. When two billiard balls collide, in which direction would they travel after the collision? If a meteorite hits the earth, why does the earth remain in its orbit? When two cars collide with each other, why is one of the cars more damaged than the other? We will find that to answer such questions, new concepts must be introduced.Ĭonsider the situation where two bodies collide with each other.