To apply the law of conservation of energy to a system, you need to carefully de

Question

To apply the law of conservation of energy to a system, you need to carefully define which objects make up the system and which belong to the environment. The tactics outlined here will help you make wise choices for systems.

In the questions that follow, identify the appropriate system for applying conservation of energy to the given situation.

a. spring b. glider c. air track d. earth

I think the glider and the spring are part of the system and the earth and the air track are part of the environment, but I'm not sure.

2. A rope and pulley are used to lift a crate upward with constant speed.

a. rope b. earth c. crate d. pulley

I know that the crate is part of the system and that the pulley is part of the environment but I'm not sure about the earth or the rope.

Any help is appreciated :)

To apply the law of conservation of energy to a system, you need to carefully define which objects make up the system and which belong to the environment. The tactics outlined here will help you make wise choices for systems. If the speed of an object or objects is changing, the system should include these moving objects because their kinetic energy is changing. If the height of an object or objects is changing, the system should include the raised object(s) plus the earth. This is because potential energy is stored via the gravitational interaction of the earth with the object(s). If the compression or extension of a spring is changing, the system should include the spring because elastic potential energy is stored in the spring itself. If kinetic or rolling friction is present, the system should include the moving object and the surface on which it slides or rolls. This is because thermal energy is created in both the moving object and the surface, and we want this thermal energy to all be within the system. In the questions that follow, identify the appropriate system for applying conservation of energy to the given situation. A spring is used to launch a glider up a frictionless air track that is inclined at a 25 angle to the horizontal. spring b. glider c. air track d. earth think the glider and the spring are part of the system and the earth and the air track are part of the environment, but I'm not sure. A rope and pulley are used to lift a crate upward with constant speed. rope b. earth c. crate d. pulley

Explanation / Answer

a. spring b. glider for the system

the potential enrgy of the spring is converted to kinetic enrgy of the glider and then to potential enrgy of the glider

the crate is the system as only the height of the crate will tells us how much energy was used to lift it up

the rope can be part of the environment if it is considered mass less if the rope has some mass and if the pulley also has mass then all theree i.e crate ,rope and pulley will form the system

this is because the crate will have potential enrgy .rope will also have PE and the pulley will have rotational KE

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