Why Do Spring Constants Differ Between Hooke's Law and Oscillation Method?

[VitaminK]

Homework Statement

calculate the spring constant

Relevant Equations

no equation

During an experiment, using Hooks law resulted in a spring constant of 7,8N/m while for the oscillation-method the constant was 8,6N/m. Could someone help me to clarify whay they differ and which vlsue is the correct one.

 

[kuruman]

The spring constant is, as the name implies, a constant that is independent of your method of measuring it. You got different values probably because of some systematic error in your measurements. Only you know what you did and how you did it, so you are best qualified to figure out which value you tthink is more accurate. Did you perform one measurement with each method or are these numbers averages of many measurements with each method? For all I know, the values that you got are within the uncertainty of your measurements.

 

[VitaminK]

The spring constant is, as the name implies, a constant that is independent of your method of measuring it. You got different values probably because of some systematic error in your measurements. Only you know what you did and how you did it, so you are best qualified to figure out which value you tthink is more accurate. Did you perform one measurement with each method or are these numbers averages of many measurements with each method? For all I know, the values that you got are within the uncertainty of your measurements.

Thanks! Yeah I just performed one measurement with each method.

 

[kuruman]

Thanks! Yeah I just performed one measurement with each method.

Which one do you trust most? Which one leaves ore room for error? Next time try to make more than one measuements. This will give you a better idea of how bunched together your measurements are.

 

[VitaminK]

Which one do you trust most? Which one leaves ore room for error? Next time try to make more than one measuements. This will give you a better idea of how bunched together your measurements are.

Well I'd say the oscillating-method is more trustworthy, since it only depends on one variable (mass) that can be measured more accurately than the elongation x in F=kx. But i don't know if this is true?

 

[archaic]

Well I'd say the oscillating-method is more trustworthy, since it only depends on one variable (mass) that can be measured more accurately than the elongation x in F=kx. But i don't know if this is true?

Don't you have to also take account of the oscillation period? For me, measuring time manually through a stopwatch, for example, is way untrustworthy than measuring a distance with a meter stick, because of our reflexes.

 

[kuruman]

Well I'd say the oscillating-method is more trustworthy, since it only depends on one variable (mass) that can be measured more accurately than the elongation x in F=kx. But i don't know if this is true?

I am guessing that for the oscillating method you also had to measure the period. How accurately did you measure that? What did you use? Depending on what you used, either method could be accurate than the other. For example, a photogate is more accurate than the timer app on your smartphone for timing oscillations; a transit level is more accurate than a meter stickr for measuring distances. Only you can estimate the accuracy what you did because you were there and I was not.

A crude way to do that would be to say something like, "I measured the length to be 10.3 cm, but it could be as little as 10.1 or as big as 10.5 because of parallax effects and because couldn't exactly gauge where the beginning and the end of the length was." Now that you have these brackets, recalculate the spring constant using the low and high value for x to find a high and low value for the spring constant. Then do the same type thing for the time measurement considering how you did it. See if there is a overlap of the values measured by the two methods.

 

[VitaminK]

I am guessing that for the oscillating method you also had to measure the period. How accurately did you measure that? What did you use? Depending on what you used, either method could be accurate than the other. For example, a photogate is more accurate than the timer app on your smartphone for timing oscillations; a transit level is more accurate than a meter stickr for measuring distances. Only you can estimate the accuracy what you did because you were there and I was not.

A crude way to do that would be to say something like, "I measured the length to be 10.3 cm, but it could be as little as 10.1 or as big as 10.5 because of parallax effects and because couldn't exactly gauge where the beginning and the end of the length was." Now that you have these brackets, recalculate the spring constant using the low and high value for x to find a high and low value for the spring constant. Then do the same type thing for the time measurement considering how you did it. See if there is a overlap of the values measured by the two methods.

I did measure the period for 10 oscillations (10T) and I used a regular timer so there are several errors here. Again thank you !