[Julii92]

a/ A simple pendulum consists of a small metal ball attached to a fixed point by a cord of length L centimetres. It takes T seconds to make one swing, where T=0.2√L. Find dT/dL.

b/ The cord originally has length 2.5 metres. If it is lengthened by 2 millimetres, calculate what effect this will have on the time of swing.

Finding the derivative is easy enough: 0.1/√L. Unfortunately, I don't know how to use the derivative to work out what the effect will be on the time of swing when the length is increased.

[Intriguing Alias]

(Original post by Julii92)
a/ A simple pendulum consists of a small metal ball attached to a fixed point by a cord of length L centimetres. It takes T seconds to make one swing, where T=0.2√L. Find dT/dL.

b/ The cord originally has length 2.5 metres. If it is lengthened by 2 millimetres, calculate what effect this will have on the time of swing.

Finding the derivative is easy enough: 0.1/√L. Unfortunately, I don't know how to use the derivative to work out what the effect will be on the time of swing when the length is increased.

You don't need to use the derivative.

T=0.2√L Sub in L = 2.5 to get original time, and then L = 2.502 to get the new time, then the difference is the 'effect'.

[Julii92]

(Original post by hassi94)
You don't need to use the derivative.

T=0.2√L Sub in L = 2.5 to get original time, and then L = 2.502 to get the new time, then the difference is the 'effect'.

Thanks for answering but the textbook explicitly says to find the answer using the derivative - I should have mentioned.

[Julii92]

bump