Forces, Space, and Radioactivity

Scalar

A quantity that only has magnitude, such as distance, which is the length of the path between starting and ending points.

Give an example of a scalar quantity

Speed

Vector

A quantity that has both magnitude and direction, like displacement, which is the shortest distance from starting to ending points.

Give an example of a vector quantity

Velocity

Acceleration

The change in velocity over time, a vector quantity measured in m/s².

Distance-Time Graphs

Graphs with time on the x-axis and distance on the y-axis, where the slope represents velocity.

Velocity-Time Graphs

Graphs with time on the x-axis and velocity on the y-axis, where the slope represents acceleration.

How do you calculate displacement from a velocity-time graph?

Area under the velocity-time graph

How do you calculate acceleration from a velocity-time graph?

Slope of the velocity-time graph

How do you calculate velocity from an acceleration-time graph?

Area of an acceleration-time graph

How do you calculate velocity from a distance-time graph?

Slope of the distance-time graph

What are the two types of stopping distance?

Thinking distance and braking distance

What is the thinking distance?

distance covered by the car while the driver comprehends the situation / reacts to it

What is the braking distance?

distance covered by the car from when the driver hits the brakes and the car stops.

What are crumple zones?

present at the front of the car, so that when a car crashes, the crumple zone takes the impact first

Newton’s First Law

An object stays in motion/at rest until an external force is applied, with balanced and unbalanced forces affecting motion.

Inertia

an inherent property of an object that resists motion

Newton’s Second Law

States that force causes acceleration, with F = m*a as the relationship.

Newton’s Third Law

Every force has an equal and opposite force, seen in actions like walking or rocket propulsion.

Work

Done when a force moves an object over a distance, represented by W = F*d in joules (J).

Gravitational Potential Energy

An object has gravitational potential energy when it is elevated from the ground to a certain height.

Kinetic Energy

An object has kinetic energy when it is in motion.

Elastic Potential Energy

An object has elastic potential energy when its shape is changed (eg. through stretching, compressing)

Hooke’s Law

The force needed to extend or compress a spring by some distance is proportional to that distance

Energy Efficiency

Concerns the conversion of energy in vehicles, influenced by factors like friction and air resistance.

Momentum

The tendency of a moving object to stay in motion, defined as p = m*v in kg m/s.

Conservation of Momentum

States that in a closed system, total momentum is conserved.

Comets

balls of rock and ice that orbit the sun. When they come really close to the sun, melts this ice forming an ice tail.

Asteroids

large rocks that are found between Mars and Jupiter in a belt known as the Asteroid Belt.

Hertzsprung-Russel (H-R) Diagram

A graph that represents stars according to their luminosity (y-axis) and temperature (x-axis).

Diffraction grating

A material that, when light passes through it, creates a continuous emission spectrum. Eg. a prism.

Continuous emission spectrum

a spectrum that contains all wavelengths emitted by a hot, dense light source.

Doppler Shift

when the movement of an object causes either the compression or stretching of waves.

Half-Life

The time taken for half of a radioactive substance to decay, measured in Bq, with various isotopes having different half-lives.

Atomic Number

the number of protons in an atom. It is denoted by Z.

Mass Number

the sum of protons and neutrons in an atom. It is denoted by A.

Isotope

an atom with the same number of protons but different number of neutrons. Eg. Deuterium (Protons: 1, Neutrons: 2), Tritium (Protons: 1, Neutrons: 3).

Alpha Radiation

An alpha particle consists of 2 protons, 2 neutrons, and 0 electrons.

Beta Radiation

Consists of highly energized electrons released from the nucleus, where these electrons are formed from the splitting of a neutron into a proton and an electron.

Gamma Radiation

Waves with short wavelengths of high frequency.

Chain Reaction

When neutrons released from the above reaction hit other Uranium-235 atoms, causing the splitting of nuclei.

Moderator or control rods

control the rate of a nuclear reaction in a nuclear reactor by absorbing extra neutrons to ensure only one neutron is hitting the isotope.

Containment buildings

buildings that surround nuclear reactors. Radioactive materials are contained, and protected from external or restricted use.

Nuclear Fission

The splitting of a nucleus, releasing energy and neutrons, used in nuclear reactors for power generation.

Nuclear Fusion

The combining of nuclei to release energy, as seen in stars, but currently not a sustainable energy source on Earth.