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A Level Physics Further Mechanics home work help please

How do I work out the uncertainty in T Squared please including formula ? Mass spring system

and is my 4th column answers correct ?


(edited 5 months ago)
Reply 1
Looks like its for 0.6 kg for instance
0.45^2-0.39^2
right so when you want to find the uncertainty in t squared. when you are multiplying/dividing any two values in physics, you add their percentage uncertainties together. when you add/subtract any two values in physics, you add their absolute uncertainties together

so for the second row, they got the answer by:
finding the percentage uncertainty in t by 0.06/0.35, then x100 for % = 17.14%

x the percentage uncertainty by 2 (because you are multiplying t by t, so you add 17.14 to 17.14 = 34.29

now you know the percentage uncertainty in t squared, you can find the absolute by working out what 34.29% of 0.12 is = 0.04

ps please bare in mind any exam board differences, i do aqa physics but maybe yours does it differently so maybe do check a textbook if this seems right

also i realise i was saying t and t squared instead of t/s and t squared/ s squared but it doesn’t affect the maths so
Original post by Cam06
How do I work out the uncertainty in T Squared please including formula ? Mass spring system

and is my 4th column answers correct ?


Reply 3
Original post by MiscellaneousTSR
right so when you want to find the uncertainty in t squared. when you are multiplying/dividing any two values in physics, you add their percentage uncertainties together. when you add/subtract any two values in physics, you add their absolute uncertainties together

so for the second row, they got the answer by:
finding the percentage uncertainty in t by 0.06/0.35, then x100 for % = 17.14%

x the percentage uncertainty by 2 (because you are multiplying t by t, so you add 17.14 to 17.14 = 34.29

now you know the percentage uncertainty in t squared, you can find the absolute by working out what 34.29% of 0.12 is = 0.04

ps please bare in mind any exam board differences, i do aqa physics but maybe yours does it differently so maybe do check a textbook if this seems right

also i realise i was saying t and t squared instead of t/s and t squared/ s squared but it doesn’t affect the maths so


Thank you so much!! that helped me a lot.
Reply 4
could you help me with 1 more Questions please.

k= 131.6 Nm ^-1 +/- ( i need to find out the percentage , how do i work this out please . I'm having a brain block and maybe just need a reminder on how )
(edited 5 months ago)
Reply 5
Original post by Cam06
could you help me with 1 more Questions please.

k= 131.6 Nm ^-1 +/- ( i need to find out the percentage , how do i work this out please . I'm having a brain block and maybe just need a reminder on how )

You must have the basic formula
T = 2pi sqrt(m/k)
so rearrange for k and sub the range as per #2 so T+/-0.03 for the uncertainty, though it could be done a bit more efficiently.

Also in the OP 0.058 is not to 2dp, thats 2 sig fig.
(edited 5 months ago)
Reply 6
Original post by mqb2766
You must have the basic formula
T = 2pi sqrt(m/k)
so rearrange for k and sub the range as per #2 so T+/-0.03 for the uncertainty, though it could be done a bit more efficiently.

Also in the OP 0.058 is not to 2dp, thats 2 sig fig.

Also in the OP 0.058 is not to 2dp, thats 2 sig fig (would be 0.06 which corrected after i posted my OP )

the basic formula doesn't really help me ( it being too hot may be why. :confused: )
Reply 7
Original post by Cam06
Also in the OP 0.058 is not to 2dp, thats 2 sig fig (would be 0.06 which corrected after i posted my OP )

the basic formula doesn't really help me ( it being too hot may be why. :confused: )


What are you confused about with the basic formula, you know T, m and want to find k so just rearrange. Then sub T+/-0.03 to get the uncertainty.
Original post by Cam06
could you help me with 1 more Questions please.

k= 131.6 Nm ^-1 +/- ( i need to find out the percentage , how do i work this out please . I'm having a brain block and maybe just need a reminder on how )


Hi, I know it may be a bit late. How do you find k?
Are you asking for percentage uncertainty or uncertainty?

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