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###### A Level Physics Further Mechanics home work help please

Reply 2

5 months ago

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

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 ?

and is my 4th column answers correct ?

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

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.

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 )

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)

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.

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. )

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. )

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

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.

Reply 8

5 months ago

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 )

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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