Definitions Flashcards
What is a wave?
A wave can transfer energy without transferring matter
What is a wavefront?
The peaks of transverse waves
The compressions of a longitudinal wave
Used to illustrate wave motion
Giga- (G)
x10^9
Mega- (M)
x10^6
Kilo- (k)
x10^3
Centi- (c)
x10^-2
Milli- (m)
x10^-3
Micro- (µ)
x10^-6
Nano- (n)
x10^-9
Describe the process of terminal velocity
Weight acts downwards
Drag acts upwards
Person accelerates downwards
Eventually weight = drag
No resultant force, no acceleration, forces are balanced
Terminal velocity (constant velocity) is reached
What is stopping distance?
The distance travelled by a vehicle after a hazard has been spotted until it comes to a complete rest (thinking distance + braking distance)
What factors affect braking distance?
Condition of road, tyres and breaks
What factors affect thinking distance?
Tiredness, drink and drugs
What is conservation of energy?
Energy cannot be created or destroyed, it can only be converted from one form into another
Describe the changes in the way energy is stored when an object is projected upwards
KE —> GPE
Describe the changes in the way energy is stored when a moving object hits an obstacle
KE of object —> KE in obstacle —> heat energy and sound energy
Infrasound
Below human hearing (20Hz)
Ultrasound
Above human hearing (20,000Hz)
How do optical fibres work
Total internal reflection
Core of fibre made of glass with high refractive index
Classing is made of glass with lower refractive index
Light entering core is at an angle greater than the critical angle so light is TIR
Examples of optical fibres
Endoscope - used in keyhole surgery
Communication as less energy is lost when compared to using copper wiring
Electromagnetic spectrum
Radio waves, microwaves, infrared, visible light, UV, X-ray, gamma ray
