Physics Terms Flashcards
displacement
Change in position. How far an object is from its starting point.
average speed
distance traveled along its path divided by the time it takes to travel this distance.
Velocity
Is a vector. Has a magnitude (numerical value) and the direction in which it is moving.
average velocity
displacement divided by time elapsed
acceleration due to gravity
9.80 m/s^2
scalars
a number and unit
vectors
has direction and magnitude
examples of scalars
mass, speed, distance
examples of vectors
velocity, acceleration, momentum, weight
inertia
tendency of a body to resist a change in its motion
mass
the measure of inertia of a body
weight
the force of gravity on a body
force
Ts considered a push or a pull. It is a vector. An action that gives rise to an acceleration.
Net Force
net force on an object is the sum of all forces acting on it
What are the two types of forces?
Contact forces and Field forces.
Which is stronger? kinetic friction or static friction?
Kinetic friction is weaker. It is easier to keep an object moving than to get it started.
Horizontal
left to right or like the x-axis
Vertical
up and down or like the y-axis
What is the difference between static and kinetic friction? Which coefficient is generally larger?
Static friction is with an object not moving, kinetic friction is to keep an object moving. Static friction is generally larger.
An object acted upon by a net force will always experience a _____, which means it will either _____ and/or _____.
acceleration; speed up, change direction, and/or slow down.
Describe velocity, acceleration, and net force when an object is in translational (linear) equilibrium.
Velocity is constant
acceleration is zero
Net Force is zero
Two objects moving together (pulled by a rope or pushing each other) share the same_____
acceleration
The normal force is always _______ to the surface.
perpendicular
perpendicular
an angle 90 degrees to another line or surface
The friction force always ______ the motion (or the intent of motion) and is proportional to the ______ force.
Opposes
Normal
Given an object on an incline, list the components of its weight parallel and perpendicular to the plane.
Parallel: mg sin theta
Perpendicular: mg cos theta
While an object is in projectile motion with no air resistance…
The horizontal component of its velocity remains constant and the vertical component of the acceleration is equal to -g
A ball is tossed vertically upward. When it reaches its highest point (before falling back downward) …
The velocity is zero, the acceleration is directed downward, and the force of gravity acting on the ball is directed downward.
What are the 2 types of forces?
There are two types of forces. Contact forces are the result of two objects touching one another. Examples of
contact forces are applied forces, drag force, friction force, force normal, spring force and tension. Field forces happen
even when two interacting objects are not touching one another. Examples of Field forces are gravitational force,
magnetic force and electric force.
Tension
Tension force or the force of tension (T or FT) is the force transmitted through a rope, cable, string or wire pulled taut by forces acting on both ends.
Newton’s Third Law
Newton’s Third Law states that in every interaction, there is a pair of forces acting on the two interacting objects.
The size of the forces on the first object equals the size of the force on the second object. The direction of the force on
the first object is opposite to the direction of the force on the second object
Friction Force
The friction force is the force exerted by a surface as an object moves across it or makes an effort to move across
it.
Frictions Forces
Kinetic friction is weaker than static friction, as it is easier to keep an object sliding once it is sliding than to start
an object sliding in the first place (Newton’s 1st law). Therefore, there are two types of µ, denoted with subscripts. For a
given pair of surfaces, it is true that µk < µs.
A projectile has no horizontal acceleration and so moves at a constant velocity in the horizontal.
true
A projectile is in free fall, so its vertical acceleration is aways -10 m/s^2
true
The vertical displacement of a projectile launched and landing at the same level is aways zero
true
Forces at Angles
If the net force has both a vertical and a horizontal component, use the Pythagorean theorem to determine the magnitude of the net force, and use the tangent function to determine the direction of the net force.
Object in Free fall
When an object is in free fall, its acceleration is 10 m/s per second10 toward the ground. “Free fall” means no forces other than the object’s weight are acting on the object.
Projectile’s horizontal acceleration
A projectile has no horizontal acceleration, and so it moves at constant speed horizontally. A projectile is in free fall, so its vertical acceleration is 10 m/s per second downward
The horizontal and vertical motion charts for a projectile must use the same value for
time.
In a position-time graph, the object’s position is read from the vertical axis.
In a position-time graph, the object’s speed is the slope of the graph. The steeper the slope, the faster the object moves. If the slope is a front slash (/), the movement is in the positive direction; if the slope is a backslash (), the movement is in the negative direction.
In a velocity-time graph, the object’s speed is read from the vertical axis. The direction of motion is indicated by the sign on the vertical axis.
In a velocity-time graph, the object’s acceleration is the slope of the graph.
In a velocity-time graph, the object’s displacement is given by the area between the graph and the horizontal axis. The location of the object can’t be determined from a velocity time graph; only how far it ended up from its starting point can be determined.
