Motion and Forces

What is a FORCE? A push or pull that one object exerts on another object List 5 everyday experiences you have that you apply a force either a push or pull) to an object.

FORCES Forces can change the following 3 things: Speed of the object Direction of the object Shape of the object

BALANCED VS. UNBALANCED FORCES Balanced Force: Equal forces acting on an object. Forces that produce a net force of zero. NO motion occurs. Unbalanced Force: Unequal forces acting on an object. Forces that produce a positive net force. Motion occurs.

What is the NET FORCE? The combination of all the forces acting on an object. FORCES ALWAYS COME IN PAIRS!!!!

Calculation Net Force 100 N + 100 N = 0 N Balanced Force No Motion

75 N + 125 N = 50 N Unbalanced Force : Motion to the Left Calculating Net Force 75 N + 125 N = 50 N Unbalanced Force : Motion to the Left

Types of Forces Applied Force: A push or pull Invisible Force: Gravity: A force that pulls objects toward the Earth (or other object) Friction: The force that two surfaces exert on each other when they rub against each other Name 5 activities that are easier to do due to gravity. Name 5 activities that are harder to do due to gravity.

Friction 2 Factors that depend on force of friction: how hard the surfaces are pushing together Types of surfaces involved Provide 3 examples of friction in our daily lives.

4 Types of Friction Static Friction: Acts on objects that are not moving Provide 3 examples of static friction in the classroom.

4 Types of Friction Sliding Friction: Occurs when 2 solid objects slide over each other. Provide 3 examples of sliding friction in real life.

4 Types of Friction Rolling Friction: Occurs when an object rolls across a surface. Provide 3 examples of rolling friction in real life.

4 Types of Friction Fluid Friction: Occurs when a solid object moves through or over a fluid (liquid or gas) Provide 3 examples of fluid friction in real life.

Motion The state in which an object’s distance from another is changing Reference Point: A place or object used as a comparison to determine motion Are we moving right now?

How do we measure the rate of movement of an object? SPEED

Calculating Speed Distance Time Speed (Velocity) Rate of action or movement of an object, how fast or slow something moves Velocity = Distance Time Distance Time Speed (Velocity) Where in real life do we use speed to calculate objects.

Velocity The speed and direction of a moving object

Constant Speed Objects move the same distance during the same amount of time When a police officer pulls a person over does he measure a person’s constant speed, average speed, or instant speed?

Graphing Distance by Time NOT MOVING

Graphing Distance by Time Constant Speed

Graphing Distance by Time A steeper line indicates a larger distance moved in a given time. In other words, higher speed. Both lines are straight, so both speeds are constant.

Graphing Distance by Time This shows an increase in speed, since the line is getting steeper. In other words, in a given time, the distance the object moves is changed(getting larger). It is accelerating.

Graphing Distance vs. Time

Acceleration The rate of change of an object’s velocity (speed and direction) Speed up Slow down Change direction

Isaac Newton Found 3 Laws of Motion that explain much of the motion that happens in our lives.

Newton’s 1st Law of Motion An object at rest stays at rest, an object in motion stays in motion unless a force is applied. Law of Inertia: The resistance of wanting to change in motion. Depends on MASS Objects at rest remain at rest unless acted on by a net force. A lot of inertia! The large train resists changing its motion. Very little inertia. The small baby carriage has very little resistance to changes in motion.

Newton’s 2nd Law of Motion The amount of mass an object has affects the speed and force needed to push or pull.

Newton’s 3rd Law of Motion For every action there is an equal but opposite reaction.