The weight of an object is the force of gravity on the object and may be defined as the mass times the acceleration of gravity, w = mg. Since the weight is a force, its SI unit is the newton. Density is mass/volume.
COMBINED FORCES
When forces act in the same direction, they combine to make a bigger force. When they act in opposite directions, they can cancel one another out. If the forces acting on an object balance, the object does not move, but may change shape.Weight is a force which is a vector and has a magnitude and direction. Mass is a scalar. Weight and mass are related to one another, but they are not the same quantity. `
If N is the number of forces acting on a body, the net force formula is given by,
- FNet = F1 + F2 + F3…. + FN.
- FNet = Fa + Fg.
- FNet = Fa + Fg + Ff + FN.
The sum of all the forces acting on an object is the net force or resultant force. If all the forces cancel out, the resultant force is zero, else, the unbalanced force will cause acceleration of the object. Force is a vector and hence has both a direction and magnitude.
A push is the force that moves an object away from something, like when you push a plate of Brussels sprouts away in disgust. A push and a pull are opposite forces, meaning they move objects in different directions. Therefore, a pull is the force of bringing an object closer.
Static friction is strongest, followed by sliding friction, and then rolling friction, which is weakest.
Balance forces are two forces acting in opposite directions on an object, and equal in size. Anytime there is a balanced force on an object, the object stays still or continues moving continues to move at the same speed and in the same direction.
Gravity is a force of attraction that exists between any two masses, any two bodies, any two particles. Gravity is not just the attraction between objects and the Earth. It is an attraction that exists between all objects, everywhere in the universe.
How to find force of friction
- Choose the normal force acting between the object and the ground. Let's assume a normal force of 250 N.
- Determine the friction coefficient.
- Multiply these values by each other: 250 N * 0.13 = 32.5 N .
- You just found the force of friction!
Free-body diagrams are diagrams used to show the relative magnitude and direction of all forces acting upon an object in a given situation. A free-body diagram is a special example of the vector diagrams that were discussed in an earlier unit. These diagrams will be used throughout our study of physics.
The normal force is the support force exerted upon an object that is in contact with another stable object. For example, if a book is resting upon a surface, then the surface is exerting an upward force upon the book in order to support the weight of the book.
Lesson: In Statics the Sum of the Forces is Equal to Zero. The term statics refers to an object or system in static equilibrium. The sum of the forces is equal to the mass times the acceleration. The 2nd law tells us that if the object or system is motionless, the acceleration is equal to zero.
Two types of multiplication involving two vectors are defined: the so-called scalar product (or "dot product") and the so-called vector product (or "cross product"). When two arbitrary vectors are multiplied, the scalar product has a similar meaning, but the magnitude of the number is a little different.
Graphically, we add two vectors a and b by positioning the tail of b at the head of a and then creating a new vector starting from the tail of a and ending at the head of b. Subtracting vectors follows basically the same procedure as addition, except the vector being subtracted is "reversed" in direction.
Vectors. Two vectors are equal if they have the same magnitude and direction. They are parallel if they have the same or opposite direction. We can combine vectors by adding them, the sum of two vectors is called the resultant.
A vector is a quantity or phenomenon that has two independent properties: magnitude and direction. Examples of vectors in nature are velocity, momentum, force, electromagnetic fields, and weight. (Weight is the force produced by the acceleration of gravity acting on a mass.)
Although vectors and scalars represent different types of physical quantities, it is sometimes necessary for them to interact. While adding a scalar to a vector is impossible because of their different dimensions in space, it is possible to multiply a vector by a scalar.
FORCES ARE VECTORS. This means they have both SIZE and DIRECTION. When adding forces, we must add them like lines, taking LENGTH and ANGLE into account. Adding forces is the same as combining them.
No, in general you cannot divide one vector by another. It is possible to prove that no vector multiplication on three dimensions will be well-behaved enough to have division as we understand it.
Magnitude and Direction
| From Polar Coordinates (r,θ) to Cartesian Coordinates (x,y) | From Cartesian Coordinates (x,y) to Polar Coordinates (r,θ) |
|---|
| x = r × cos( θ ) y = r × sin( θ ) | r = √ ( x2 + y2 ) θ = tan−1 ( y / x ) |
