How much does a steel measuring tape expand on a hot day?

[nickb145]

Homework Statement

A 61.00m long steel measuring tape is calibrated for use at 20.0∘C. How long is this tape under the following conditions:

a hot day with 38∘C?
Express your answer using four decimal places and include the appropriate units.
i've been losing my mind over this, i swear I'm doing it correctly.

Homework Equations

ΔL/L=αΔT

The Attempt at a Solution

(38-20)=18°C

(61m)(1.2*10^-5)(18)= .01317m

Mastering physics keeps telling me that I'm inncorrrect , I swear I'm doing it how the book wants me to do it.

 

[TSny]

The Attempt at a Solution

(38-20)=18°C

(61m)(1.2*10^-5)(18)= .01317m

Is this the length of the tape or the change in the length of the tape?

 

[nickb145]

it is the change in L

 

[gneill]

(38-20)=18°C

(61m)(1.2*10^-5)(18)= .01317m

Mastering physics keeps telling me that I'm inncorrrect , I swear I'm doing it how the book wants me to do it.

it is the change in L

Does it make sense that a 61 meter long steel tape shrunk to about 1.3 cm in length?

 

[nickb145]

obviously not.

 

[gneill]

obviously not.

So. What is it that your formula is giving you?

 

[nickb145]

the amount the metal is changing in length. Silly me, i didn't add it together

 

[gneill]

the amount the metal is changing in length. Silly me, i didn't add it together

Huzzah!