Newton’s 1st Law & Friction
Newton’s 1st Law states that if the net force on an object is zero, this happens to its motion.
It does not change (stays at rest or moves at a constant velocity).
According to the 2nd Law, acceleration is equal to net force divided by this.
Mass
This law states that when one object applies a force on a second object, the second object applies an equal force back in the opposite direction.
Newton’s 3rd Law.
This is the name for the force a surface applies to push back on an object; it is always perpendicular to the surface.
Normal Force
This is the sum of all forces acting on an object.
Net Force
This term describes the tendency of an object to resist a change in its motion—it's why you keep moving forward when a car stops suddenly.
Inertia.
True or False: Acceleration always moves in the same direction as the net force.
True
If you push on a wall with 50N of force, the wall pushes back on you with this much force.
50N
"Perpendicular" means the Normal Force always acts at this specific angle to the surface.
90 degrees
If a 5N force pushes right and a 5N force pushes left, the forces are considered __________.
Balanced
This contact force always acts in the opposite direction of a sliding object's motion.
Friction.
This is the standard unit used to measure Force in physics.
Newtons (N)
Force pairs do not cancel each other out because they act on different ___________.
Objects
This simple drawing uses arrows to show every individual force acting on an object.
Free-Body Diagram
Acceleration is a measure of the change in ________ during a period of time.
Velocity
To get a heavy dresser to start moving, your push must be stronger than this specific force holding it back.
Static Friction.
If you double the force applied to an object but keep the mass the same, what happens to the acceleration?
It doubles (Direct Relation).
When you jump, your legs push down on the Earth. What is the reaction force that actually moves you upward?
The Earth pushing up on your feet.
If a book is sitting on a table, the two forces acting on it are gravity (pulling down) and this (pushing up).
Normal Force
These are the three ways an object can accelerate.
Speed up, slow down, or change direction.
This occurs when the upward force of air resistance perfectly matches the downward force of gravity on a falling object.
Terminal Velocity.
A 2kg ball is pushed with a net force of 10N. What is the acceleration?
5 m/s² (10 / 2 = 5).
In this type of collision, objects hit each other and then stick together, moving as one.
Inelastic Collision
On a Free-Body Diagram, what does the length of the arrow represent?
The strength or magnitude of the force.
A 10kg box is being pushed right with 50N and pulled left by friction with 20N. What is the acceleration?
3 m/s² (Net Force is 30N; 30 / 10 = 3).