Forces PDF

SCALAR AND VECTOR QUANTITIES Lesson Objectives: 1. I can differentiate scalar quantities from vector quantities. 2. I can describe what a force is. 3. I can classify force as a vector quantity. 4. I can describe the effects of forces on objects.  WHAT IS SCALAR QUANTITY? It is a q...

SCALAR AND VECTOR QUANTITIES Lesson Objectives: 1. I can differentiate scalar quantities from vector quantities. 2. I can describe what a force is. 3. I can classify force as a vector quantity. 4. I can describe the effects of forces on objects.  WHAT IS SCALAR QUANTITY? It is a quantity that has magnitude only and has NO DIRECTION in space. Examples: ❖ Mass ❖ Speed ❖ Time ❖ Temperature  WHAT IS SCALAR QUANTITY? It is described by a single number and unit of measurement. Examples: ❖ Mass – 20 g ❖ Speed – 13 m/s ❖ Time – 15 s ❖ Temperature – 37oC  WHAT IS VECTOR QUANTITY? It is a quantity that has BOTH MAGNITUDE AND DIRECTION in space. Examples: ❖ Velocity ❖ Acceleration ❖ Force  WHAT IS VECTOR QUANTITY? It indicates direction (head of arrow). Examples: ❖ 30 m/s, East ❖ 25 m/s, N of E SCALAR OR VECTOR 8 m/s West VECTOR  100°F SCALAR 22 m North VECTOR 2000 Joules SCALAR  5 kg SCALAR 250 kg m/s southwest VECTOR 15 km/hr SCALAR 12.0 m/s² downwards VECTOR 1,500 kg SCALAR 35 N to the right VECTOR  A force is a push or pull that can change an object's motion or shape. Effects of forces on objects A force can change the size and shape of an object. A force can make a stationary object move. A force can speed up, slow down, or stop a moving object A force can change the direction of a moving object. Types of Forces Acting Between Objects Contactforce - requires physical touch between objects Non-contact force – an act over a distance without physical touch A magnet attracting iron nails Non-contact Force  An apple falling from a tree due to Earth's gravity Non-contact Force  A car slowing down on a road due to friction between tires and the surface Contact Force  A book resting on a table, where the table exerts an upward force on the book Contact Force Pushing a shopping cart Contact Force Stretching a rubber band Contact Force A balloon sticking to a wall after being rubbed on hair Non-contact Force  BALANCED AND UNBALANCED FORCES Lesson Objectives: 1. I can differentiate balanced force from unbalanced force. 2. I can identify and describe everyday situations that demonstrate balanced and unbalanced forces. 3. I can cite some situations which involve balanced and unbalanced forces.  Balanced force Unbalanced force An object at An object acted upon An object acted upon rest stays by a balanced force by an unbalanced at rest. stays at rest. force changes speed and direction.  Unbalanced force An object at rest An object acted upon by stays at rest. an unbalanced force changes speed and direction.  Unbalanced force An object in motion An object acted upon by an unbalanced force changes stays in motion. speed and direction. A B Balanced Forces 1 Equal and Opposite Balanced forces act on an object in opposite directions and are equal in magnitude. 2 No Change in Motion When forces are balanced, the object remains at rest or continues moving at a constant speed and direction. Unbalanced Forces 1 Unequal Forces Unbalanced forces act on an object in opposite directions but are unequal in magnitude. 2 Change in Motion When forces are unbalanced, the object's motion changes, causing acceleration or deceleration. A book lying on a table Balanced Force An accelerating car Unbalanced Force Launching a rocket Unbalanced Force A box resting on an inclined plane Balanced Force A boat floating on still water Balanced Force A freely falling fruit Unbalanced Force A light source hanging at the ceiling Balanced Force  Opening a door Unbalanced Force Pushing a box across the floor Unbalanced Force A man standing still Balanced Force Summary Balanced forces occur when the forces acting on an object cancel each other out, resulting in no change in motion (the object stays at rest or moves at a constant velocity). Unbalanced forces occur when one force is stronger than the other, causing the object to accelerate, decelerate, or change direction.