Science 8 Forces PDF

SCIENCE 8 Does force always make objects move?  WHAT CAN WHAT ARE THESE FORCES DO? CHANGES IN MOTION? Activity 1: Effect of force on a ball TYPES OF FORCE Which of these activity shows frictional force? Non-contact forces – forces where objects do not touch or contact with each...

SCIENCE 8 Does force always make objects move?  WHAT CAN WHAT ARE THESE FORCES DO? CHANGES IN MOTION? Activity 1: Effect of force on a ball TYPES OF FORCE Which of these activity shows frictional force? Non-contact forces – forces where objects do not touch or contact with each other. These forces act over a zone or area called field. Examples of non-contact forces: 1. Gravitational (Fg) – is the force of attraction between two objects. In the case of the Earth, this gravitational force causes objects to fall down to the ground. It makes satellites and smaller objects stay in orbit near the more massive planets. Mass and distance of the two objects affect the gravitational force that holds them. The bigger the masses of the objects are, the bigger is the gravitational force between them. The closer the objects are, the greater is the gravitational force between them.  The weight of an object, denoted by W, is an example of the gravitational force of the Earth towards the object. In figure 13, the weight of a book (𝑊𝐵𝑂𝑂𝐾 ) is illustrated. However, the weight of an object depends on the mass of the celestial body where the object is attracted to. Meaning, we seem to be lighter when we are on the moon than on the Earth 2. Magnetic– are forces exerted on a field of attraction or repulsion as in the case of magnets and other magnetic materials. Magnets and magnetic materials have two poles – the north and south poles. Attraction may occur when two poles are not the same, a positive and a negative while repulsion takes place with the same poles, positive-positive and negative-negative.  Balanced Forces   Unbalanced Forces    Net force or resultant force is the sum of all forces acting on an object. Two or more forces in the same line of action exerted on an object are balanced if their effects cancel each other. When an object is at rest, a zero net force would make the object remains at rest. Moreover, when the object is moving, a zero net force would make the object maintain its velocity at a given time interval.  On the other hand, when the net force is not zero, the object’s velocity will change. A net force exerted to an object at rest may cause the object to move. In a moving object, a net force will increase its velocity when the force is in the same direction of its motion. If the net force is in the opposite direction of the object’s motion, the force will reduce the object’s velocity. When the net force acts sideways on a moving object, the direction of the object’s velocity changes.