Physics 2

• Describe the forces acting on a main sequence star

  Inward gravitational force is equal to the outward force caused by nuclear fusion i.e. the forces are balanced.
• what is the relationship kinetic energy and work done by the brakes?

  The work done by the brakes is equal to the reduction in kinetic energy
• State factors that may affect a vehicle‘s breaking distance

  adverse road and weather conditions, poor condition of vehicle, speed
• what is meant by the conservation of momentum?

  In a closed system, the total momentum before an event is equal to the momentum after.
• State Newton’s third law


  Whenever two objects interact, the forces they exert on each other are equal and opposite
• State Newton‘s second law

  The acceleration of an object is proportional to the resultant force acting on the object and inversely proportional to the mass of the object (F=ma)
• State Newton’s first law


  If the resultant force on an object is zero, and the object is stationary, it will remain stationary. If the object is moving, it will continue to move at the same velocity.
• what is the difference between distance and displacement?

  Distance is, how far is something moves (not including direction). Displacement is measured in a straight line from start points to finish point and includes direction.
• How do unlike poles interact?

  They attract
• define longitudinal waves


  The oscillations are parallel to the direction of travel
• what is the acceleration of a falling object near earth?

  9.8 m/s squared
• define contact and noncontact forces and give examples

  Contact forces are objects physically touching e.g. friction or air resistance.

  Non-contact forces are when the objects are physically separated, e.g. a falling object.
• give me equation that links moment, force and distance

  Moment = force x distance
• describe the relationship between emission and absorption of radiation from an object (body), increasing temperature


  The object (body) absorbs radiation faster than it emits radiation
• give the equation that links change in momentum, time and force

  Force = change momentum/time taken for change
• why is iron used in the construction of a transformer


  As it is easily magnetised
• what does The Big Bang Theory suggest?

  The universe began from a small region that was extremely hot and dense.
• what name is given to the turning effect caused by a force

  Moment
• what states can fluid be?

  Liquid or gas?
• stick the range of normal human hearing

  20 Hz to 20kHz
• List the uses of each part of the electromagnetic spectrum

  Radio waves: television and radio

  Microwaves: satellite communications and cooking food

  Infrared radiation: electrical heaters, cooking food and infrared cameras

  Visible light: fibre optic communications

  Ultraviolet: energy-efficient lamps, sun tanning

  X-rays and gamma: medical imaging and treatments
• keep the equation for calculating speed

  Speed = distance/time
• what is an induced magnet?


  A material that becomes a magnet when placed inside a magnetic field
• give the wave speed, equation state, the units

  Wave speed (m/s) = frequency (Hz) x wavelength (m)
• how does altitude affect atmospheric pressure?

  Decreases with altitude
• State the unit for moment

  Newton-meter
• what is meant by resultant force?


  The remaining force when forces in all directions have cancelled each other out.
• why does a light ray change direction during refraction?

  Due to change in wave speed
• how do you like poles interact

  they repel
• in what direction do magnetic fields run?


  North to south
• describe Flemings left hand rule


  Thumb, first finger and second finger are held mutually at right angles. The thumb points in the direction of the motion (Force), the first finger in the direction of the magnetic field, the second finger in the direction of the current.
• what name is given to reflection from a rough surface?


  Diffuse reflection
• Our solar system is part of which galaxy?

  Milky Way
• State the unit for pressure

  Pascals
• when will an object appear black


  When all wavelengths are absorbed equally
• what name is given to the reflection from a smooth surface?

  Specular reflection
• describe the relationship between a mission and absorption of radiation for an object (body) at constant temperature

  The object (body) is absorbing and emitting radiation at the same rate
• which three types of waves can harm human body tissues?

  Ultraviolet, x-ray, gamma rays
• name the area of force around a magnet

  Magnetic field
• give the equation that links magnification, image height and object height

  Magnification = image height/object height