Homework Help: physics

Posted by Daniel on Saturday, March 17, 2012 at 11:37pm.

A convex mirror in an amusement park has a radius of curvature of 3.00m. A man stands in front of the mirror so that his image is half as tall as his actual height. At what distance must the man focus his eyes in order to see his image?

I calculated the focal length using f=(-.5)(3.00m)

then I tried to find the image distance(di) but I get stuck.

What am I supposed to be doing here?

physics - drwls, Sunday, March 18, 2012 at 1:36am
You have correctly determined that f = -1.5 m for this mirror. From the magnification of 1/2, and the fact that it is a virtual image, you also know that
di/do = -1/2.

Therefore 1/di + 1/do = 1/di - 1/2di =
1/2di = 1/f = -2/3

Therefore di = -3/2 m and do = 3 m

Since the observer is the "object" and his image is on the other side of the mirror, he must focus his eyes 4.5 meters away.

Check my thinking. I could have made a mistake somewhere
physics - scott, Thursday, April 11, 2013 at 1:35pm
you kind of just droped 1/di there. where did it go?

I just dont get how you got to:

1/di - 1/2di

and then you went from

1/di - 1/2di = 1/2di.....you just droped 1/di. That doesnt make any since.

Answer this Question

Related Questions

College Physics - An amusement park mirror shows anyone who stands 2.5 meters in...
Physics - Mirrors & Lenses - When standing 1.25 m in front of an amusement ...
physics - An object is placed in front of a convex mirror with a 22.6-cm radius ...
physics - A person stands in front of a mirror at an amusement park. the person...
physics - A 4.5 cm tall object is placed 20 cm in front of a spherical mirror. ...
Physics - A convex mirror has a radius of curvature of 36.0 cm. When a 5.60 cm ...
physics - The radius of curvature of a convex mirror is 1.60 x 102 cm. An object...
Physics - A candle is placed 17.0 cm in front of a convex mirror. When the ...
Physics - A convex mirror forms an image of height of 2.4 cm, If the radius of ...
theoretical optics - A man 1.5meter tall stands in front of a concave mirror ...

For Further Reading

First Name:
School Subject:
Answer: