Presentation on theme: "المحاضرة السابعة The Laws of Motion Chapter 5 5.1 The Concept of Force The body is moving, When it change its position during a limited time."— Presentation transcript:
المحاضرة السابعة The Laws of Motion
5.1 The Concept of Force The body is moving, When it change its position during a limited time.
5.1 The Concept of Force Types of Motion:
5.1 The Concept of Force. An object accelerates due to an external force.. Force is a vector quantity
Definition of equilibrium object is in equilibrium if: The net force acting on the object is zero,. The object remains at rest.. or continues to move with constant velocity.
Measuring the Strength of a Force It is convenient to use the deformation of a spring to measure force.
Newton s laws of motion Newton s laws of motion
FIRST NEWTONs LAW SECOND NEWTONs LAW THIRD NEWTONs LAW
5.2 Newtons First Law Newtons first law (law of inertia): In the absence of external forces, an object at rest remains at rest and an object in motion continues in motion with a constant velocity (that is, with a constant speed in a straight line).
5.3 Mass. Mass (m) is that property of an object that specifies how much resistance an object exhibits to changes in its velocity.. The SI unit of mass is the kilogram (Kg).. mass is a scalar quantity
Mass and weight The Weight of an object (W):. W = the gravitational force exerted on the object. W varies with location The Mass (m):. Is the same everywhere
5.4 Newtons Second Law The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. :is the net force a : the acceleration. m: mass.
5.4 Newtons Second Law SI unit of force: CGS unit of force:
5.4 Newtons Second Law
5.5 The Gravitational Force and Weight Gravitational force Fg :The attractive force exerted by the Earth on an object.. The magnitude of Fg:. Direction: Toward the center of earth
5.5 The Gravitational Force and Weight
5.6 Newtons Third Law If two objects interact, the force F 12 exerted by object 1 on object 2 is equal in magnitude and opposite in direction to the force F 21 exerted by object 2 on object 1:
5.6 Newtons Third Law The action force is equal in magnitude to the reaction force and opposite in direction. The action and reaction forces:. act on different objects.. and must be of the same type.
5.6 Newtons Third Law
5.7 Some Applications of Newtons Laws. Tension Force. Frictional Force: (in opposite of mosion direction). Elevator. The Atwood Machine. Inclined surface
Example 5.4 A Traffic Light at Rest
One Block Pushes Another
Example 5.8 Weighing a Fish in an Elevator
The Atwood Machine
Acceleration of Two Objects Connected by a Cord