Forces & Motion
What is the unit of force?
Newton (N)
What is the unit of energy?
Joule (J)
What is the unit of current?
Ampere (A)
What is the unit of frequency?
Hertz (Hz)
What force keeps planets in orbit around the Sun?
Gravity
What does a resultant force of zero mean for an object’s motion?
It is at rest or moving at constant velocity
What is the equation for kinetic energy?
Ek = 1/2(mv2)
What is the equation linking current, charge, and time?
I = Q ÷ t
What type of wave is a light wave?
Transverse
What is a star?
A massive ball of hot gas undergoing nuclear fusion
What does Newton's 2nd law state?
F = ma
What is meant by conservation of energy?
Energy cannot be created or destoyed
How does current behave in a series circuit?
It is the same throughout
What happens to wave speed when frequency increases but wavelength decreases proportionally?
It stays the same
What is the life cycle stage of a star like the Sun after the main sequence?
Red giant
What is terminal velocity?
The constant speed reached when drag equals weight
What is power?
The rate of energy transfer
How does voltage behave in a parallel circuit?
It is the same across each branch
What is refraction?
The change in direction of a wave when it enters a different medium
What is a supernova?
A massive explosion of a star
Why does an object reach terminal velocity when falling through a fluid?
Because resistive forces increase until they balance the driving force (weight), so acceleration becomes zero
Why is no energy transfer ever 100% efficient?
Some energy is always dissipated (usually as heat) to the surroundings
Why does increasing resistance reduce current (for a fixed voltage)?
Because higher resistance opposes the flow of charge more strongly
Why does a wave change direction when it enters a different medium?
Its speed changes, causing it to bend
What determines the life cycle of a star?
Its mass