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

[单选题]
The length of a pencil isueimz bs3yln*;.d0o nx 99,gf measured g96hx4jo /ujvusing part of a measuring tape as shown belowhj6vxjo/ g49u .

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 lookingibzspo 4/zh x xa78j m-r)3b0notpx ;l2l8o2q at the cm scale! The uncertainty in a reading on a scale is usually taken as ha3b2 zxb0xm) r 8hoq-z/i;8p47lasnop t x ojl2lf the smallest division. Here the smallest division is 0.5 cm 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.