3.6 Newton’s second law

Newton’s second law says:   If the sum of the external forces acting on an observed object is not zero, then the object is accelerating in the direction of the resultant of the forces acting on it.  The sum of all external forces acting on the observed object is calculated as follows: multiply the mass of […]

3.5 Newton’s third law

Newton’s third law When considering the Newton’s third law, a pair of forces between two objects is observed.     The Newton’s third law or action equals reaction says:  If one object acts on another one with a certain force, the other object acts back with an equal, but oppositely directed force. Let’s take a look […]

3.4 Newton’s first law

The Newton’s first law The first Newton’s law says: When the sum of all external forces applied on the observed object is zero, an object is standing still or moving uniformly. The external forces on the object are in balance.   Let’s take a look on the forces applied on a vase. The figure shows […]

3.3 Drawing the forces

Drawing the forces Vectors are directed lines. Also, forces are illustrated with them. On the sketches, the used agreed marking is F. The length of the vector is used to represent the magnitude of the force. The direction of the vector is used to represent the direction of the force. The point at which we […]

3.2 Measurement of forces

Measurement of forces The instruments used to measure the forces are spring scales or force meters.  A spring is used to make a force meter. The spring is stretched by the force and returns to its original shape when the force is no longer applied. The more the spring stretches, the greater the force applied […]

3.1 Description of forces

Description of forces Some of the natural phenomena are consequences of applied forces. When describing forces, first, the observed object needs to be determined. For example, a pear falls from a tree. The observed object is the pear, and everything else is the surroundings.  When a force is applied on the observed object, it can […]

3.0 Forces

Forces Forces are physical quantities used to describe the action of one object on another object. In this chapter you will learn: How to describe forces? How we measure forces? How to illustrate forces? Newton’s laws