Vocabulary
velocity
rate at which an object's position changes in time
What is "dynamic equilibrium"?
What is "static equilibrium"?
dynamic: the state in which the net force acting upon a moving object is zero and the object stays in motion at a constant speed and direction.
static: when all forces acting on an object are balanced and the object stays at rest.
Give an example of non-contact force:
- gravity
- magnetic forces
- nuclear force
When graphing velocity, what does a straight line represent?
The line will be straight when velocity is changing at a constant rate (a steady speed)
Question: Which quantity is SCALAR:
a. velocity
b. energy
c. momentum
d. force
b. energy
What is Newton's Second Law of Motion?
states that the acceleration of an object is directly proportional to the force on it and INVERSELY proportional to the object's mass
...
states that net force = mass x acceleration
slope
a measure of steepness of a line, calculated by dividing the change in the y-axis by the change in the x-axis of two points
What is the equation to find force (tell me what it stands for)?
F = ma; force = mass x acceleration
You kick a soccer ball and it hits the goal post and flies back toward you. What is this an example of?
Newton's Third Law of Motion: for every action, there is an equal and opposite reaction.
On a distance vs. time graph, what should be labeled on the VERTICAL (up and down) axis?
a. distance
b. time
c. speed
a. distance
the amount or size of a force
momentum
the sum of all forces acting on an object
net force
Give an example of contact force:
- pushing an item across a table
- friction between your feet and the ground
- pulling a rope
- kicking a soccer ball
What is the relationship between the slope of the line on a velocity vs. time graph
If mass stays the same, a steeper slope means that a stronger net force is applied.
If a rock is sitting on the ground, with a mass of 20kg, how much force is being exerted from the rock to the ground beneath it? What forces are acting on the rock?
A. Gravity is still acting on the rock, at 9.8 m/s2. Use the Force formula to solve, F = ma.
F = (20kg) (9.8m/s2)
F = 196 Newtons
acceleration
Give me the formula as well!!
rate at which an object's velocity changes in time
A = change in velocity /time
what does "DELTA" mean?
change in relationship or differences between numbers
- force (mass and acceleration)
- displacement (change of position, with arrow)
- momentum (magnitude and direction to predict speed and direction)
- velocity (magnitude and direction)
DRAW a graph of velocity vs. time showing a car increasing in speed
*PICTURE*
The graph of an object's position over time is a horizontal line and "y" is not equal to 0. What must be true about the object's motion?
a. acceleration is negative
b. velocity is constant and non-zero
c. acceleration is constant and non-zero
d. velocity is zero
d. velocity is zero
What is Newton's Third Law of Motion?
for every action there is an equal and opposite reaction
Give an example of balanced force(s)
- standing still on the ground
- fruit hanging from a tree
- a book lying flat on a table
- a plane in steady flight
If a person is biking at a velocity (v) going west on top of a train while the train is going the same speed heading east, what is the state of equilibrium? Explain.
This represents a state of dynamic equilibrium because the opposing forces of the westward bike ride and the eastern train ride are balanced, and the objects that were moving are still moving.
Explain the quantitative relationship between acceleration and net force.