What are the two theories developed by Albert Einstein?
Special relativity and general relativity.
What does special relativity deal with?
Inertial frames of reference where objects are moving at constant speed relative to one another.
What remains constant for all observers in special relativity?
The speed of light in a vacuum.
What is the speed of light in a vacuum?
3 × 10^8 m/s.
What is time dilation?
The phenomenon where time passes more slowly for an object moving at high velocity compared to a stationary observer.
What happens to the measurement of time for a moving observer compared to a stationary observer?
The moving observer’s clock appears to run slower.
What is the formula for time dilation?
t’ = t √(1 - v²/c²), where t’ is the time observed by the moving observer, t is the time observed by the stationary observer, v is the speed of the object, and c is the speed of light.
How does length contraction occur?
An object moving at high speed appears shorter in the direction of travel to a stationary observer.
What is the formula for length contraction?
l’ = l √(1 - v²/c²), where l’ is the length observed by the moving observer, l is the length observed by the stationary observer.
In the context of special relativity, what does ‘l’ represent?
The length of an object as observed by a stationary observer.
What is the effect of high velocity on the perception of time and length?
Time appears to pass more slowly and lengths appear contracted for stationary observers.
What practical evidence supports Einstein’s theory of special relativity?
Evidence from muons and satellite navigation systems.
What are muons and why are they significant in special relativity?
Muons are sub-atomic particles that travel near the speed of light and have a half-life that appears longer due to time dilation.
How does satellite navigation relate to special relativity?
Clocks in satellites move more slowly than clocks on Earth, leading to a time difference that must be corrected for accurate positioning.
What is the consequence of time dilation for a moving spaceship?
Time on the spaceship appears normal to its crew, but appears slower to a stationary observer.
What happens to the length of a fast-moving object as observed by a stationary observer?
The length appears shorter than when the object is at rest.
What is the relationship between speed and the effects of time dilation?
The higher the velocity, the more pronounced the effects of time dilation become.
What is the significance of the observer’s frame of reference in special relativity?
Each observer measures time and distance relative to their own frame of reference.
What is the expected number of muons reaching the Earth based on their half-life and speed?
It would be expected to be very low, but is actually much higher due to time dilation.
What is the effect of a moving clock in a satellite compared to a clock on Earth?
The satellite clock loses 7 microseconds a day due to its high speed.
What is meant by ‘all motion is relative’ in the context of special relativity?
Motion is always measured relative to a chosen frame of reference.
What happens to the magnitude of a meter on a fast-moving object as perceived by a stationary observer?
It is less than if the object were at rest.
What is the relationship between time and length for a stationary observer and a fast-moving object?
Time appears greater and length appears less for the fast-moving object compared to the stationary observer.
What is the significance of the speed of light in special relativity?
It is a universal constant that remains the same for all observers, regardless of their relative motion.
