Calculating the Height of a Friend's Image from 4.2m Away

  • Thread starter Thread starter matt72lsu
  • Start date Start date
  • Tags Tags
    Height Image
AI Thread Summary
To calculate the height of a friend's image from a distance of 4.2 meters, the correct approach involves using the ratio of distances (di/do) multiplied by the friend's actual height. The original attempt mistakenly included an incorrect distance value of 3.5 meters, which led to an incorrect calculation. Clarification on where the image is formed, such as on the retina, was also discussed. Ultimately, the user identified their mistake and expressed gratitude for the assistance received. Understanding the correct formula and values is crucial for accurate image height calculations.
matt72lsu
Messages
94
Reaction score
0

Homework Statement


Your friend is 1.7 m tall.

What is the height of her image when she is 4.2 m from you?


Homework Equations



I used di/do and multiplied that by the height of the friend

The Attempt at a Solution


I did (4.2/3.5)(1.7) but it was wrong. Not really sure what I'm doing wrong here.
 
Physics news on Phys.org
Where the image is formed? On the retina? What is 3.5 in your attempt?
 
nevermind I found my mistake. thanks for the help though
 

Thread 'Errors and significant figures'

I multiplied the values first without the error limit. Got 19.38. rounded it off to 2 significant figures since the given data has 2 significant figures. So = 19. For error I used the above formula. It comes out about 1.48. Now my question is. Should I write the answer as 19±1.5 (rounding 1.48 to 2 significant figures) OR should I write it as 19±1. So in short, should the error have same number of significant figures as the mean value or should it have the same number of decimal places as...
View full post »
Thread 'A cylinder connected to a hanging mass'

Thread 'A cylinder connected to a hanging mass'

Let's declare that for the cylinder, mass = M = 10 kg Radius = R = 4 m For the wall and the floor, Friction coeff = ##\mu## = 0.5 For the hanging mass, mass = m = 11 kg First, we divide the force according to their respective plane (x and y thing, correct me if I'm wrong) and according to which, cylinder or the hanging mass, they're working on. Force on the hanging mass $$mg - T = ma$$ Force(Cylinder) on y $$N_f + f_w - Mg = 0$$ Force(Cylinder) on x $$T + f_f - N_w = Ma$$ There's also...
View full post »

Similar threads

Image Magnification: Find Height of Image with f=42
Replies
5
Views
1K
Solving for image height given ##h_o, d_i##, and r
Replies
1
Views
1K
Convergent lenses and calculating image position
Replies
2
Views
1K
Calculating Image Height of Flower in Convex Mirror | Homework Question
Replies
3
Views
5K
[LENS] Given focal length and height, find object distance
Replies
1
Views
3K
Light and Optics: Shoplifter's Distance and Height
Replies
1
Views
1K
Height of the image of Jupiter created by the objective lens
Replies
3
Views
1K
Compression of human bone: forces
Replies
2
Views
6K
Calculating Image Position and Height Using Two Lenses?
Replies
5
Views
3K
Swinging Tarzan: Solving for Maximum Height & Angle
Replies
3
Views
2K

Hot Threads

Recent Insights

Back
Top