required practicals Flashcards
Describe a method that can be used to measure the speed of ripples on a water surface:
measuring the density of the liquid
measuring the density of a solid
force v extention
1) measure the natural length of the spring (when no load is applied) with a millimeter ruler clamped to the stand.
2) make sure you take the reading at Eye Level and add a marker eg a thin strip of tape to the bottom of the spring to make the reading more accurate
3) add a mass to the spring and allow the spring to come to rest
4) record the mass and measure the new length of the spring the extension is the change in length
5) repeat the process until you have enough measurements no fewer than 6
force v extention graph
Once you’ve collected your results, you can plot a force-extension graph of your results. It will only start to curve if you exceed the limit of proportionality.
When the line of best fit is a straight line it means there is a linear relationship between force and extension (they’re directly proportional, see previous page).
F = ke, so the gradient of the straight line is equal to k, the spring constant.
When the line begins to bend, the relationship is now non-linear between force and extension - the spring stretches more for each unit increase in force.
f = ma practical
1) Set up the apparatus shown above. Set up the trolley so it holds a piece of card with a gap in the middle that will interrupt the signal on the light gate twice. If you measure the length of each bit of card that will pass through the light gate and input this into the software, the light gate can measure the velocity for each bit of card. It can use this to work out the acceleration of the trolley.
2) Connect the trolley to a piece of string that goes over a pulley and is connected on the other side to a hook (that you know the mass of and can add more masses to).
3) The weight of the hook and any masses attached to it will provide the accelerating force, equal to the mass of the hook (m) x acceleration due to gravity (g).
4) The weight of the hook and masses accelerates both the trolley and the masses, so you are investigating the acceleration of the system (the trolley and the masses together).
5) Mark a starting line on the table the trolley is on, so that the trolley always travels the same distance to the light gate.
6) Place the trolley on the starting line and hold it in place. You should let the hook and any masses on the hook hang so the string is taut (not loose and touching the table). Then, release the trolley.
7) Record the acceleration measured by the light gate as the trolley passes through it. This is the acceleration of the whole system.
8) Repeat this twice more to get an average acceleration.
f = ma practical - effect of mass
f = ma practical - effect of force
f = ma practical - explanation of results
Newton’s Second Law Can Explain the Results
1) Newton’s Second Law can be written as F = ma. Here, F = weight of the hanging masses, m = mass of the whole system and a = acceleration of the system.
2) By adding masses to the trolley, the mass of the whole system increases, but the force applied to the system stays the same. This should lead to a decrease in the acceleration of the trolley, as a = F ÷ m.
3) By transferring masses to the hook, you are increasing the accelerating force without changing the mass of the whole system. So increasing the force should lead to an increase in the acceleration of the trolley.
refraction
reflection practical
SHC
effectiveness of insulators
leslie cube ir radiation emmision
leslie cube ir radiation absorbtion
waves in a solid
https://www.youtube.com/watchv=ZXAmiRC0GBo&list=PL9IouNCPbCxXmYRj7CIRPeogyK04tWoml&index=4
masses on a string to affect the string tension
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