Physics experiment, non conclusive! (1 Viewer)

[gh0stface]

Hi, i have an assessment comin up and i have to write out the practical report inclass based on a experiment done earlier (related to f=ma).

The things is, my results are nonconclusive, even after i repeat the experiment. So idk if it will affect my marks if i write the report based on nonclusive results, do results rly matter?


Please give some feedback, the assessment is comin up soon.

 

[tommykins]

They don't mark much on what you do and what not, but as long as you have the correct results (or clsoe to it) you're fine.

Results decide most of your marks in other words, a wrong result = experiment done incorrectly.

 

[gh0stface]

^ i know i did everything right. Its just that one sets of the recordings i took down were non conclusive for each of the times i did the experiment.

When you say wrong results = experiment done incorrectly, dats not necessarily true imo cos the quality of equipment may be a factor which made my results nonconclusive.

 

[Captain Gh3y]

Well

experiments are never conclusive, at best they simply fail to show that the theory is wrong

 

[gh0stface]

and by that you mean?

 

[z600]

Just write about sources of error, like friction, air resistance, incorrect timing, and moment of inertia etc....

 

[tommykins]

I know not ALWYAS wrong results = experiment done correctly, but that's the first thing you'd check if results were nowhere near as expect. In our yr level, our experiements are all pre-determined (as in, the teachers know what results to expect).

 

[gh0stface]

^My experiment was 2.3.5 in the Moving about topic.

Plan, choose equipment or resources and perform first-hand investgations to gather data and use available evidence to show the relationship between force, mass and acceleration using suitable apparatus.



Let me explain briefly: We had to show the relationship between force, mass and acceleration, so basically F=MA.

We used a trolley, ticket timer, string, pulley and weights.

So we basically have to calculate the acceleration of the trolley moving as the LOAD pulling the trolley is kept CONSTANT, while the mass put on the trolley varies. The tickettimer tape is attached at the front of the trolley so wen the trolley moves, the tape also moves and thus the tickettimer will print dots on it.

the theory is that as the load is kept constant, and the mass of weights put on trolley increases, the dots shown on the tickettimer tape will be closer together, the less weight the furthur apart the dots. -- Becos the faster it travels, the less time for the ticket timer to print dots on.


^ well when i did the experiment the first time, i tested 4 masses of weight on the trolley, the results were varying, and rejects the above theory.

the second time i did the experiment, i tested 5 masses, it was pretty consistent and conclusive until the 5th mass which was off from the rest.

______________________________________________________________

Please take the time to read this, will greatly appreciate it.

 

[z600]

^My experiment was 2.3.5 in the Moving about topic.

Plan, choose equipment or resources and perform first-hand investgations to gather data and use available evidence to show the relationship between force, mass and acceleration using suitable apparatus.



Let me explain briefly: We had to show the relationship between force, mass and acceleration, so basically F=MA.

We used a trolley, ticket timer, string, pulley and weights.

So we basically have to calculate the acceleration of the trolley moving as the LOAD pulling the trolley is kept CONSTANT, while the mass put on the trolley varies. The tickettimer tape is attached at the front of the trolley so wen the trolley moves, the tape also moves and thus the tickettimer will print dots on it.

the theory is that as the load is kept constant, and the mass of weights put on trolley increases, the dots shown on the tickettimer tape will be closer together, the less weight the furthur apart the dots. -- Becos the faster it travels, the less time for the ticket timer to print dots on.


^ well when i did the experiment the first time, i tested 4 masses of weight on the trolley, the results were varying, and rejects the above theory.

the second time i did the experiment, i tested 5 masses, it was pretty consistent and conclusive until the 5th mass which was off from the rest.

______________________________________________________________

Please take the time to read this, will greatly appreciate it.

If the weight increases, shouldn't the dots be further apart? not closer together? it falls faster therefore the more tape runs through between each clicks. And if one weight is off from the rest, just say its a outliner from the rest of the apparatus

 

[sle3pe3bumz]

If the weight increases, shouldn't the dots be further apart? not closer together? it falls faster therefore the more tape runs through between each clicks. And if one weight is off from the rest, just say its a outliner from the rest of the apparatus

That's only if you change the weights which are hanging off the table. With his experiment, he applied a load on the trolley, making it travel slower. But you would be correct if he were to change the weights.

The experiment we done at school was changing the weights rather than the load.

 

[imnotkarl]

i do physics as well, my schol do the course backwards..motion first, the world communicates second, electrical energy third and space fourth.

as i repeated yr11, this is my second year of prelim physics, from experience, teachers, nor HSC (VET for other states) markers will deduct marks for inconclusive results as long as you display the correct proceduce of operations, eg: the experiment. as long as you write up your prac report and INCLUDE a discussion on where your hypothesis went wrong or what your margins of errors were they wilkl actually, possibly award you more points.

in science its not the final answer that matters most, its the understabnding of how that answer is created. if they only wantyed final answers they would give your copious mathematics!

if your school has a dynamics cart, a set of pulleys, and some dead wheights, set itr up on a metre high bench and use accelleration due to gravity to judge. of course timeing it would be effective!

as long as you show them you understand!
i hope ive been of some help to you,
cheers,
pat

 

[misbahf]

We did this experiment at school except rather we did ours a little bit different.

1. we set the trolley up on a table and attached ticker tape to it.
2. on the opposite end of the trolley we tied string to it.
3. We tied a weight to the string (25g).
And this bit may be your error.
4. We let the weight drop off the table. This way the acceleration was constant (9.8m/s) which made it easier to find force and prove the theory.

Here is the picture i used in my experimental report if you need to clarify.

 

[misbahf]

OH just to add, you keep adding weights onto the end of the string and recording your results. Your results should be conclusive.