Earth History & Extinctions
The history of life on Earth based on the traces of living things left in layers of rock.
What is the fossil record?
The energy of motion.
What is kinetic energy?
A push or a pull exerted on an object, measured in units called newtons (N).
What is a force?
The rate at which an object travels a given distance over time (Distance / Time).
What is speed?
According to Newton’s Third Law, when one object exerts a force on a second object, the second object exerts a force that is equal in strength and in this direction.
What is opposite direction (equal and opposite force pairs)?
According to the law of superposition, when looking at undisturbed rock layers, where are the older layers located?
What is at the bottom (below the newer layers)?
Stored energy that an object has based on its position, condition, or chemical composition.
What is potential energy?
Newton’s First Law states that an object at rest stays at rest, and an object in motion stays in motion with a constant velocity, unless acted on by this type of force.
What is an unbalanced force
(or net force not equal to 0N)?
The speed of an object in a particular direction.
What is velocity?
A force that opposes motion between two surfaces that are in contact, which frequently causes a moving object's kinetic energy to turn into thermal or sound energy.
What is friction?
This element, rare on Earth's surface but common in space, was found in a 66-million-year-old global clay layer and signaled an asteroid impact.
What is iridium (the iridium anomaly)?
State the formula used to calculate work, including what the variables stand for.
What is W = Fd
Work = (Force)(distance)
State Newton’s second law equation that solves for acceleration using force and mass.
What is a = F/m?
(or F = ma)
The rate at which velocity changes over time (changes in speed, direction, or both).
What is acceleration?
In the engineering design process, after engineers identify and define a problem, what are the next two key steps they take?
What are developing/testing solutions and optimizing solutions?
This method of dating rock layers involves studying radioactive isotope decay to determine the absolute age of rocks.
What is studying radioactive isotope decay (or absolute dating)?
How much work is done if a robot exerts a force of 25N to push a crate across a distance of 4 meters in the direction of the force?
What is 100 Joules
(25N)(4m)= 100Nm
If you apply a net force of 20N to a 4kg box, what will its acceleration be?
What is 5m/s^2
(20N/4kg)?
The tendency of objects to resist any change in motion.
(Hint: Mass is a direct measure of this).
What is inertia?
When a massive truck collides with a stationary bicycle, the force the truck exerts on the bike is equal in strength to the force the bike exerts on the truck. Why is the damage to the bicycle so much worse?
What is because the bike has much less mass, meaning it experiences a much greater acceleration (a = F/m) during the collision?
Why do scientists conclude that the end-Cretaceous mass extinction might have had multiple causes rather than just one?
What is because evidence shows that massive volcanic eruptions (like the Deccan Traps) occurred before, during, and after the asteroid impact, releasing climate-altering gases that also contributed to the extinction?
A roller coaster starts with potential energy at the top of a hill, transforms it into kinetic energy on the way down, but eventually stops at the end of the ride even on a flat track. What law explains where the energy went, and what form did it take?
What is the Law of Conservation of Energy
(Energy is transformed into thermal energy and sound energy due to friction)
Two teams in a tug-of-war pull on opposite ends of a rope with exactly 600N of force each. What is the net force, and will the rope accelerate?
What is a net force of 0N, meaning the forces are balanced and the rope will not accelerate?
Why does a ball thrown upward have a positive velocity on the way up, but a negative velocity when it falls back down?
What is because velocity uses positive and negative signs to indicate opposite directions of travel?
Why are crumple zones built into modern cars considered an effective engineering solution to protect passengers during high-speed crashes?
What is because allowing the car to deform extends the duration of the collision, which reduces the overall force experienced by the passengers?