PAPER 2 - practice questions Flashcards
explain when an object might topple over
centre of mass is the point at which the weight of an object acts through.
an object will topple over whn the centre of mass falls outside the base of the object
describe what can effect the stopping distance of a lorry
- stopping distance is thinking distance plus braking distance
- thinking - tiredness, distractions, drugs or alcohol
- breaking - condition of tyres, condition of brakes, wet/icy - less friction, heavy and fast it will take longer
explain how an egg dropped into a polystyrene foam prevents the egg from breaking
- soft foam increases the time it takes for egg to stop
- this decreases the rate momentum changes which reduces the force on the egg
- as this force is reduced the egg doesnt crack
explain in terms of conservation of energy what will happen when a person dives from a stationary boat
- momentum before is equal to the momentum after
- before mom of boat and diver is 0kgm/s so after it must be 0 too
- after driving the person has a small velocity and momentum in forwards direction
- therfore boat will have the same in the opposite direction
identify what happens to pressure with increasing altitude
- altitude increases pressure decreases
- bc pressure is molecules colliding with a surface
- and so as the altitude increases the distance between molecules increases so at a higher altitude there are fewer molecules
- so the number of collisions with the surface decreases
what happens to pressure with increasing depth
- as depth increases pressure increases
- bc increasing depth increases height of water above
- which increases the force of water from above
explain how upthrust occurs
- object in water will experince more pressure at bottom than top
- bc part thats deeper under water has a greater height of water above it exerting a force
- this difference in pressure creates a resultant force which is upthrust
compare sound waves with x rays ( any longitudinal wave with transverse)
- sound waves are longitudinal so parallel
- x rays are tranverse so perpendicular
- sound waves cant travel through a vacum but x rays can (all tranverse waves can travell throguh vacuum)
- sound waves travel slower
compare the use of x- rays and ultra violet light
- x rays detect broken bones, locate bullets and detect dental problems and kill cancer
- ultraviolet - pre natal scanning, remove plaque from teeth, steralise, give suntan, security pens
- x rays ionising and can mutate dna and damage cells - cancer
- ultra violet is the same
describe the apparenece of a red object in a room with green light only
- red object would NORMALLY appear red in white light bc it would reflect red parts of the spectrum and absorb everything eklese
- BUT IN GREEN LIGHT - it will absorb all green light and no reflect ANY LIGHT AT ALL
- so the object will apear black
explain how you could determine if a substance is magnetic or non magnetic
- put it next to a permanent magnet
1. if it has no effect then it is non megnetic
2. attracts or repels - it is megnetic
describe how to plot magnetic field patterns around a bar magnet
- put magnet of paper and outline the bar
- put a dot by a pole of magnet and put compass on dot
- put dot at tip of compass needle and move compass tail to new dot
- repeat until it reaches the other pole of magnet
- then draw lines through the dots and add arrow from north to south to show direction of field lines
- repeat starting at dif starting positions
explain why compass needles move when placed near a bar magnet
- bc the compass needle is a small bar magnet so they exert a forc on each other
- so they can attract or repel each other
explain why the wire moves when the switch is closed for the motor effect
- when switch closed the wire has current bc circuit is complete
- this creates mag field around wire
- this interacts with permanemt field of magnet
- creating a force on the wire causing it to move
describe how to build and test and electromagnet
- wrap a coil of wire around an iron nail or core
- connect wire to power supply with crocodile clips and turn it on
- to increase the strnegth - more coils, more current
- to test use paperclips and see if they stick to it and if more stick to it when you increase the strength