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How do you know if an object is in motion?
An object is in motion if its distance from a reference point is changing.
What is distance?
It is the total length traveled.
What is displacement?
The distance between the starting and ending point of an object.
What is speed?
It is the rate at which an object covers distance. The SI unit is m/s.
What are the two types of speed and what to they describe?
Average Speed: The total distance/total time
Instantaneous Speed: The speed an object is traveling at a given moment in time
What is acceleration?
It is a measure of how velocity (speed and/or direction) changes in a given time.
What are some examples of acceleration?
Speeding up, slowing down, and changing direction
The SI unit is m/s/s
There is positive acceleration (speeding up) and negative acceleration (slowing down)
What does a distance/time graph show?
It shows speed - time is on the x-axis and distance is on the y-axis
What does a curved line on a distance/time graph show?
It shows acceleration (how it changes).
What does it mean when a line is super steep, medium, and horizontal on a distance time graph? How would you describe this on the test?
Super steep: Means its going super fast
Medium steep: It means that its not going super fast but still fast
Horizontal: DO NOT DESCRIBE IT AS HORIZONTAL ON THE TEST!!! Describe it as, for example, the object remained at 80m for 2 min. This line means the object is not moving.
What is mass?
It is the amount of matter in a material.
What is weight?
It is a measure of how the force of gravity acts upon the mass of the object.
What do forces do?
It can cause an object to change its motion (accelerate aka measure of changing velocity) or maintain its current motion.
What are the two types of forces? What is a common force for each one?
Contact: Friction
Non-contact: Gravity
What is friction?
It is a force that resists motion between two surfaces that are in contact with each other.
What is gravity? What does it depend on?
It is the attractive force that objects exert on each other. The force of gravity depends on the mass of the objects and the distance between them.
How are forces measured?
In Newtons (N) using a spring scale.
What is a balanced force?
It is when all the forces acting on an object are equal (there is NO CHANGE in motion aka there is a constant velocity).
What is an unbalanced force?
When one or more forces acting on an object are stronger than the others (there IS a change in motion; velocity changes).
What is net force?
The overall force acting on an object when all of the forces acting on it are combined (in other words: the leftover force). **Adding and subtracting here is common!
Sort: Friction, buoyancy, magnetism, gravity, spring, and normal into contact/non-contact forces
Friction = contact
Buoyancy = contact
Magnetism = non-contact
Gravity = non-contact
Spring = contact
Normal = contact
What is buoyancy?
The upward force exerted on an object that is placed in a fluid (liquid, gas) that opposes the object’s weight.
What is magnetism?
The force exerted between magnetic poles that either attracts them to each other or repels them from each other.
What is spring force?
The force exerted by a compressed or stretched spring on any object that is attached to it.
What is normal force?
The upward force exerted on an object that is in physical contact with another stable object, such as a table or a chair.
What is Newton’s 1st Law of Motion? (Plus an example of it)
Newton’s 1st Law is: An object at rest will remain at rest and an object will motion will stay in motion unless acted upon by an unbalanced force.
In other words: An object will maintain its current motion until an unbalanced force acts on it.
Ex: If you have a scooter and it hits gravel, causing it to slow down (in this case friction is the unbalanced force changing the scooter’s motion).
What is inertia?
The tendency of an object to do what it’s already doing.
**The amount of inertia an object has depends on its mass! (More mass - more inertia; less mass - less inertia).
What is Newton’s 2nd Law? (Plus an example)
An object’s acceleration depends on its mass and the net force acting on it.
F=ma (force = mass x acceleration)
Ex: When a baseball bat and baseball collide, the baseball will accelerate more than the bat (because the baseball has less mass)
Notes:
Applying a larger net force to an object results in a larger acceleration - this is because acceleration and force change in the same way
If an equal amount of force was applied to two objects, the object with a smaller mass will accelerate more - this is because acceleration and mass change in the opposite way
If you want two objects to accelerate at the same rate, the object with a greater mass will require greater force
What’s Newton’s 3rd Law? (Plus an example)
When one object applies a force on a second object, the second object applies a force on the first object that is equal and opposite.
AKA: Action and reaction! When an object exerts force on another object, the object will react with the same amount of force that is opposite.
Ex: When a baseball bat and baseball collide, they both exert equal and opposing forces on each other.
Note 
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