Tuesday, January 8, 2019

The sides of a cube are measured with calipers. The measured length of each side is (30.0 ± 0.1) mm.


Question 14
The sides of a cube are measured with calipers.

The measured length of each side is (30.0 ± 0.1) mm.

The measurements are used to calculate the volume of the cube.

What is the percentage uncertainty in the calculated value of the volume?
A 0.01%                      B 0.3%                        C 1%               D 3%





Reference: Past Exam Paper – June 2018 Paper 11 Q5





Solution:
Answer: C.

Length L = (30.0 ± 0.1) mm


Volume V = L3
Volume V = 303 = 27 000 mm3  


Since V = L3,
ΔV / V = 3 × ΔL / L

Percentage uncertainty in V = (3 × ΔL / L) × 100%
Percentage uncertainty in V = (3 × 0.1/30) × 100%

Percentage uncertainty in V = 1 %
at

8 comments:

  1. PlatinumApril 2, 2019 at 5:30 PM

    Uh I think you did 14 wrong.

    ReplyDelete
    Replies
    1. AdminApril 3, 2019 at 11:23 PM

      what is wrong?

      Delete
    2. AnonymousMay 11, 2019 at 7:08 AM

      It's just the answer at the end. It is supposed to be 1 % but you, by mistake have written .01%. -Thanks for the concept, helped me a lot

      Delete
    3. AdminMay 11, 2019 at 9:12 PM

      thanks. it has been corrected

      Delete
  2. AnonymousJune 27, 2019 at 3:51 PM

    9702 w18 qp11.The force resisting the motion of a car is proportional to the square of the car’s speed. The
    magnitude of the force at a speed of 20.0 m s–1 is 800 N.
    What useful output power is required from the car’s engine to maintain a steady speed of
    40.0 m s–1?

    ReplyDelete
    Replies
    1. AdminJune 27, 2019 at 9:42 PM

      go to
      http://physics-ref.blogspot.com/2019/06/the-force-resisting-motion-of-car-is.html

      Delete
  3. PrisonmikeJune 16, 2021 at 3:45 PM

    the length of a strip is measured by a metre scale as 3.4 cm if the same length is measured by a vernier calliper then reading is

    ReplyDelete
    Replies
    1. AdminJune 16, 2021 at 9:24 PM

      3.40 cm as a vernier can give a more precise value

      Delete

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