FCAT Review - 9 Forces & Motion

1 - What is FORCE? Force- a push or a pull that one object exerts on another object with or without direct contact All forces have both direction and size

2 - What are the two main categories of forces? Contact Force (must be touching) Non-contact forces (act at a distance) *Air resistance *Friction *Gravity *Electrical force *Magnetic force

A) Contact Forces Contact force- type of force that result when two objects are physically contacting each other Air resistance Friction

A) Contact Forces Air resistance

A) Contact Forces Friction

Balanced vs. Unbalanced Balanced forces- forces that are equal in size but opposite in direction Results in no movement

Balanced vs. Unbalanced Unbalanced forces- forces that are unequal in size and may or may not be opposite in direction Results in acceleration

Why is the motion towards the right in the bottom picture above?

Net Force Net force is the total of all forces acting on an object. If the net force is zero, the forces are balanced. If the net force is not zero, the forces are unbalanced.

Net Force Examples Which direction will the ball move and with how much force?

Practice!

B) Non-Contact Forces Push or pull without touching Electrical force- force between two charged objects Static cling Magnetic force- attraction or repulsion of two magnetic poles Magnets Gravitational force- the force that pulls objects straight down toward the center of the earth A dropped object falling to the ground

Factors Affecting Gravity Law of Universal Gravitation Mass -- The more mass an object has, the greater the gravitational force between it and other objects. Distance As distance increases, gravitational force decreases.

Mass vs. Weight Weight - the amount of gravitational pull on an object Mass - the amount of matter in an object

2 - Speed & Direction Speed – the rate of motion Speed = Distance ÷ Time

3 - Speed & Direction Acceleration – a change in speed or direction Positive acceleration – speeding up Negative acceleration – slowing down When an object moves either at a constant speed or is stationary, the forces are balanced.

Distance vs. Time Graph Ashley is drawing a graph that shows four different objects and the distance each object travels in 5 seconds. Which line on the graph shows the object that is traveling with the fastest constant speed? A. Line A B. Line B C. Line C D. Line D

Distance vs. Time Graph Which line on the graph shows the object that is traveling with a changing speed? A. Line A B. Line B C. Line C D. Line D

3 - Newton’s Laws of Motion

An object’s acceleration depends on the mass of the object and the force applied to it

For every action, there is an equal and opposite reaction. https://www.youtube.com/watch?v=mn34mnnDnKU For every action, there is an equal and opposite reaction.