WAEC and NECO CBT Software for Computers and Laptops - Candidates, Schools, Centres, Resellers - 100% Offline -Download Now
Post-UTME Past Questions - Original materials are available here - Download PDF for your school of choice + 1 year SMS alerts

The external and internal diameter of a tube are measured as (32 ± 2)mm and...

Physics
JAMB 1993

The external and internal diameter of a tube are measured as (32 ± 2)mm and (21 ± 1)mm respectively. Determine the percentage error in the thickness of the tube.

  • A. 27%
  • B. 14%
  • C. 9%
  • D. 3%
WAEC and NECO CBT Software for Computers and Laptops - Candidates, Schools, Centres, Resellers - 100% Offline -Download Now
Your School's Whatsapp Group - Join Us now
WAEC and NECO CBT App for Mobile Devices - Candidates, Schools, Centres, Resellers - 100% Offline -Download Now
Correct Answer: Option A
Explanation

The thickness of the tube is given by:

thickness = (external diameter − internal diameter) / 2  
= (32 − 21) / 2  
= 11 / 2  
= 5.5 mm

Let t = thickness = \(\frac{(D − d)}{2}\), where D = external diameter and d = internal diameter.

The absolute error in thickness is found using the rules for propagation of errors (for subtraction and division by a constant):

Δt = \(\frac{(ΔD + Δd)}{2}\) 
= \(\frac{(2 + 1)}{2}\) = \(\frac{3}{2}\)  
=1.5 mm.

The percentage error in thickness is:

Percentage error = \(\frac{Δt }{\text{t}}\) × 100%  
= (\(\frac{1.5}{ 5.5}\)) × 100%  
= (\(\frac{15}{ 55}\)) × 100%  
= (\(\frac{3}{11}\)) × 100% ≈ 27.27%


Report an Error Ask A Question Download App
Post UTME Past Questions Agent
WAEC and NECO CBT App for Mobile Devices - Candidates, Schools, Centres, Resellers - 100% Offline -Download Now
Post-UTME Past Questions - Original materials are available here - Download PDF for your school of choice + 1 year SMS alerts

Contributions ({{ comment_count }})

Please wait...

{{ settings.no_comment_msg ? settings.no_comment_msg : 'There are no comments' }}

Quick Questions

Post your Contribution

Please don't post or ask to join a "Group" or "Whatsapp Group" as a comment. It will be deleted. To join or start a group, please click here

{{ quote.posted_by.display_name }}
{{ settings.form_textarea_description }}
 
Post UTME Past Questions Agent
Post-UTME Past Questions - Original materials are available here - Download PDF for your school of choice + 1 year SMS alerts
WAEC and NECO CBT App for Mobile Devices - Candidates, Schools, Centres, Resellers - 100% Offline -Download Now
Your School's Whatsapp Group - Join Us now
WAEC and NECO CBT Software for Computers and Laptops - Candidates, Schools, Centres, Resellers - 100% Offline -Download Now
WAEC and NECO CBT Software for Computers and Laptops - Candidates, Schools, Centres, Resellers - 100% Offline -Download Now
Post UTME Past Questions Agent
WAEC and NECO CBT App for Mobile Devices - Candidates, Schools, Centres, Resellers - 100% Offline -Download Now
Your School's Whatsapp Group - Join Us now