Objectives Generally describe what a force is and name some common forces. Describe a scenario that demonstrates the property of inertia. Understand the concept of action and reaction forces. Compare the effect of friction on the movement of an object over a variety of surfaces. Materials See individual activities for materials.
Vocabulary force : A push or a pull action on an object. Related Resources Pendulum of Doom When we lift a pendulum, we transfer energy to it. This energy allows it to swing back and forth when we…. Drop of Doom Inquiry In a simple one-pulley system, the heavier weight will move down and pull the lighter weight up.
When the…. A vector is a one dimensional array with elements of both magnitude and direction. The equation for force is written:. Related concepts to force include thrust, which increases the velocity of an object; drag, which decreases the velocity of an object; and torque which produces changes in rotational speed of an object.
Forces which do not act uniformly on all parts of a body will also cause mechanical stresses, a technical term for influences which cause deformation of matter. While mechanical stress can remain embedded in a solid object, gradually deforming it, mechanical stress in a fluid determines changes in its pressure and volume. Dynamics is the study of the forces that cause objects and systems to move.
To understand this, we need a working definition of force. Our intuitive definition of force — that is, a push or a pull —is a good place to start. We know that a push or pull has both magnitude and direction therefore, it is a vector quantity and can vary considerably in each regard. The top left example is that of a pulley system.
The force that someone would have to pull down on the cable would have to equal and exceed the force made by the mass the object and the effects of gravity on those object in order for the system to move up. The top right example shows that any object resting on a surface will still exert force on that surface.
The bottom example is that of two magnets being attracted to each other due to magnetic force. Examples of Force : Some situations in which forces are at play. Mass is a physical property of matter that depends on size and shape of matter, and is expressed as kilograms by the SI system.
All elements have physical properties whose values can help describe an elements physical state. Changes to these properties can describe elemental transformations. Furthermore, because forces are vectors, the effect of an individual force upon an object is often canceled by the effect of another force.
For example, the effect of a Newton upward force acting upon a book is canceled by the effect of a Newton downward force acting upon the book. In such instances, it is said that the two individual forces balance each other ; there would be no unbalanced force acting upon the book.
Other situations could be imagined in which two of the individual vector forces cancel each other "balance" , yet a third individual force exists that is not balanced by another force. For example, imagine a book sliding across the rough surface of a table from left to right. The downward force of gravity and the upward force of the table supporting the book act in opposite directions and thus balance each other. However, the force of friction acts leftwards, and there is no rightward force to balance it.
In this case, an unbalanced force acts upon the book to change its state of motion. The exact details of drawing free-body diagrams are discussed later. For now, the emphasis is upon the fact that a force is a vector quantity that has a direction. The importance of this fact will become clear as we analyze the individual forces acting upon an object later in this lesson. Physics Tutorial. My Cart Subscription Selection. Student Extras.
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