required practicals p2 Flashcards
stretching a spring
acquire equiptment-clamps, clamp stand, heavy weight
next attach a metre ruler and a spring
the top of the spring must be at the zero point on the metre ruler
measure unstretched length of the spring
record, then add a 1N weight on the spring
record that down
continue adding 1n weight to the spring and reading the position of the pointer
work out the extension produced by adding each weight- unsettled minus each reading
extension is …
directly proportional to weight
adding too much weight…
to the spring causes the graph to change, by overstretching the spring we have exceeded the limit of proportionality
acceleration practical
toy car attached to a piece of string
the string is looped around a pulley and at the other end of the string is attached to a 1n weight
on the desk draw chalk lines at equal spaces eq every 10cm
hold toy car at start point and when ready let go of the car
because there is resultant force acting through the string the car will accelerate along the bench
using stopwatch record how long it takes to get to the end of the bench
repeat experiment several times and decrease the weight each time
how does newtons second law link to the practical
newton second law tells us that the acceleration of an object is proportional to the force applied
the acceleration of the car is…
is proportional to the weight on the other end of the string
what can you also investigate
how varying the mass of an object affects the acceleration produced by a constant force
how varying the mass of an object affects the acceleration produced by a constant force experiment
keep the force constant eg keep 1N weight
attach mass to the toy car eg 200g
record how long it takes the car to accelerate along the bench
repeat experimental increasing the mass attached to the toy car
as we increase the mass of the toy car, the acceleration decreases this has proven newtons second law where it states that the acceleration of an object is inversely proportional to the mass of the object
ripple tank
a ripple tank is used to observe the features of water waves
a ripple tank is a shallow tray of water. In the water is a vibrating bar
bar connected to power pack when the bar vibrates it creates waves across the surface of the water
above the ripple tank we have a lamp and below the tank we have a sheet of white paper
when light shines on the water it produces an image of the waves on the paper
record waves using a mobile phone so you are able to freeze image
with the freeze image, we can measure the distance between one wave and the ten waves
how do you find the frequency in the wave practical
we need to place a timer next to the paper and count the number of waves passing a point per second
so we calculate the no of waves in 10 secs and then divide by ten
record and watch in slow motion
equation for wave speed
fq times wl
reflection and reflection practical
use a ray box a lens and a slit this produces a narrow ray of light
1- take piece of A3 paper and a draw a straight line down the centre using a ruler
then use a protractor to draw a line at right angles. this is the normal
now place a glass block against the first line so that the normal is near the centre of the block, draw around the glass block
use ray box to direct ray of light so it hits the block at the normal- this is the incident ray
adjust ray box, at a certain angle, we can see a ray reflect from the surface of the block, and we can see the transmitted ray leave the other side of the block
mark incident reflected and transmitted ray
remove the glass block
draw a in the incident and reflected ray, draw in transmitted ray so it meets the position of the block
draw a line to show the path of the transmitted ray through the glass block
use protractor to measure both the angle of incidence and the angle of reflection and the measure angle of reflection
repeat experiment with different materials
infrared experiment
using a leslies cube
fill leslies cube with hot water
we then point an infrared detector at each of the four surfaces and record the infrared emitted
keep the same distance between leslies cube and infrared detector, this makes measurements repeatable
If you do not have infrared detector use a thermometer with the bulb painted black
what we notice is that the matte black has the highest amount of infrared emission then the shiny black surface, then the white surface,, the surface with the least amount of infrared radiation is the shiny metallic surface
resolution difference between thermometer and infrared detector
resolution of thermometer is less than infrared detector
measuring absorption of a infrared from different surfaces
we have infrared heater and on either side we have two metal plates
one plate has been painted with shiny metallic paint the other plate has been painted with matt black paint
on both of the plates on the outside of them we have vasoline to attach a drawing pin
switch on heater and start timer
the temp of the metal plates increase as they absorb infrared
we record the time it takes for the Vaseline to melt and the drawing pins to fall off
drawing pin falls off matt black surface first, because matt black surfaces absorb more infrared than shiny metallic surfaces
