What is the length of Joe's image in the mirror?

  • Thread starter Thread starter jcvince17
  • Start date Start date
  • Tags Tags
    Image Mirror
Click For Summary
SUMMARY

Joe, who is 1.6 meters tall, encounters a large convex mirror with a radius of curvature of 30 meters. When calculating the length of his image after falling forward, the correct approach involves using the mirror equation and magnification principles. The calculations yield a height of 0.98 meters for Joe's image when he is parallel to the mirror's axis. This solution clarifies the importance of considering the orientation of the object in relation to the mirror.

PREREQUISITES
  • Understanding of convex mirrors and their properties
  • Familiarity with the mirror equation: 1/f = 1/s' + 1/s
  • Knowledge of magnification concepts: m = y'/y = s'/s
  • Basic principles of optics related to image formation
NEXT STEPS
  • Study the derivation and applications of the mirror equation in optics
  • Explore the effects of object orientation on image characteristics in convex mirrors
  • Learn about the differences between real and virtual images in curved mirrors
  • Investigate advanced optics concepts such as ray diagrams for convex mirrors
USEFUL FOR

Students studying physics, particularly those focusing on optics, as well as educators seeking to explain image formation in convex mirrors.

jcvince17
Messages
40
Reaction score
0

Homework Statement



A guy named Joe, who is 1.6 meters tall, enters a room in which someone has placed a large convex mirror with radius of curvature equal to 30 meters. The mirror has been cut in half, so that the axis of the mirror is at ground level. As Joe enters the room, he is 5 meters in front of the mirror, but he is looking the other way, so he fails to see it. When he turns around, he is startled by his own image in the mirror. ( i calculated 8.75m for this answer and its correct.)
NOW:
Joe is so startled by his image that he falls forward. (Assume that his feet stay at the same position.)

Now what is the length (i.e., the distance from head to toe) of Joe's image


Homework Equations



1/f = 1/s' + 1/s

m = y'/y = s'/s

The Attempt at a Solution



f = 15m

I calculated 1.2 and got this as a reply to my wrong answer:
This was Joe's height when standing. Since he has fallen, his length is now parallel to the axis of the mirror instead of perpendicular. Therefore, the normal magnification equation does not apply. See the hint for help

I now have two chances left for a correct answer. I do not know what I am doing wrong. I am sure I am just not thinking of something simple again.

please help.

here is picture:
101033B.jpg

 
Physics news on Phys.org
Hi jcvince17!
jcvince17 said:
1/f = 1/s' + 1/s

Just use that equation twice: once for his feet, and once for his head. :wink:
 
tiny-tim said:
Hi jcvince17!


Just use that equation twice: once for his feet, and once for his head. :wink:


doing so i get:

1/-15 = 1/s' + 1/3.4
s' (head) = -2.77

1/-15 = 1/s' + 1/5
s' (feet) = -3.75

so i subtract these two numbers and have an answer of 0.98 m

Thank You!
 
Last edited:

Similar threads

  • · Replies 2 ·
Replies
2
Views
1K
  • · Replies 11 ·
Replies
11
Views
1K
  • · Replies 16 ·
Replies
16
Views
2K
  • · Replies 5 ·
Replies
5
Views
3K
Replies
6
Views
2K
Replies
14
Views
4K
  • · Replies 3 ·
Replies
3
Views
4K
Replies
5
Views
2K
Replies
9
Views
3K
  • · Replies 1 ·
Replies
1
Views
2K