Kognity IB Physics A.0 Measurements & Uncertainty (id: 294aaa607)

[单选题]
The length of a pencil is meyvr o o7f0q-e hpgt*88asured using part of a measuring tape as shown below-8ofy ph7e 80tvg*q or7 djn * t 4/m-a6h,o35vkjmjfkh r,pmwh73vnkrm j,hkwjp-a/* 4tj6m,mfd o 5.

What is the length of the pencil?

A. $4.5 \pm 0.1 \; cm$
B. $11.5 \pm 0.2 \; cm$
C. $11.5 \pm 0.3 \; cm$
D. $11.5 \pm 0.5 \; cm$


参考答案:  D


本题详细解析:
We should be looking atkv0:xw;t:z: j t qr;qg*uq0 b5rpyp7 h1y9k kj the cm scale! The uncertainty in a reading on a scale is usually taken as half the smallest division. Here the smallest division is 0.5 c p5u0qkkvb:; yzj k;g jp7: 1x* wr:qtry0ht9qm so we can read each point on the scale to an accuracy of 0.25 cm. To find the length of the pencil we must take two measurements - one for each end of the pencil. This means that we must also add the uncertainties, giving an uncertainty of 0.5cm.