dragomir Posted March 2, 2009 Report Share Posted March 2, 2009 First of all: hi everyone (even though I read this message board for longer time this is my first post ;d) I'm writing my physics lab report for simple experiment involving dropping the ball from particular height and measuring the height after it bounces off the ground. I've got a problem in identifying the controlled variables. It's obvious that the thing kept constant is the floor, but how to express it in the means of variables? My professor said that all variables should be physical quantities and hence saying that controlled variable would be simple the material of the floor is wrong. I can distinguish things like hardness or density but it's still not precise and surely not all of possible variables concerning the floor. Maybe I've become oversensitive due to all of this bureaucracy and requirements for internal assessments and there is no need to put any controlled variables in such a simple experiment? I dunno so I ask you - what do you think? Best regards, Tymon Reply Link to post Share on other sites More sharing options...
GNRS Posted March 2, 2009 Report Share Posted March 2, 2009 [quote name='dragomir' post='38703' date='Mar 2 2009, 06:06 PM'][...] from particular height and [...][/quote] This particular height, the distance between the ball's initial position and the floor, is a controlled variable (you have to keep it constant for getting valid results). Reply Link to post Share on other sites More sharing options...
deissi Posted March 4, 2009 Report Share Posted March 4, 2009 It is redundant to mention that the floor is a variable kept constant. IB is not that petty. It's not like you're going to say that the temperature of the air will be kept constant as well, since that does have an effect on the height through air resistance. Just forget about the floor, in the actual method you can just say use the same position when dropping the ball. Reply Link to post Share on other sites More sharing options...
IB_sucks Posted March 14, 2009 Report Share Posted March 14, 2009 if your changing the height drop of the ball, then the temperature actually could be a controlled variable because the temperture of the ball affects the height too. or if your changing the temperature of the ball, then drop height should be the controlled variable. Reply Link to post Share on other sites More sharing options...
Joey Posted March 22, 2009 Report Share Posted March 22, 2009 The acceleration on the ball is constant. Mass of the ball and shape of the ball is constant, as well as material Force you're throwing it to the ground (I'm assuming you're jsut letting go meaning it = 0) Thats it I think. Reply Link to post Share on other sites More sharing options...
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