Question

3. A mature blue whale may have a length of 28.0 m. How far from a con-

cave mirror with a focal length of 30.0 m must a 7.00-m-long baby blue
whale be placed to get a real image the size of a mature blue whale?

Answer 1

2.00 m in front of the concave mirror with a focal length of 30.0 m

Explanation:

To find the distance from a concave mirror with a focal length of 30.0 m at which a 7.00-m-long baby blue whale must be placed to get a real image the size of a mature blue whale, we can use the mirror equation:

1/u + 1/v = 1/f

Where u is the distance between the object and the mirror, v is the distance between the image and the mirror, and f is the focal length of the mirror.

We know that v is negative because the image is real, and the same size of the mature blue whale that is 28m.

So, we can substitute the values we know into the equation:

1/u - 1/28 = 1/30

We can solve for u by multiplying both sides by 30u and getting:

30 - 28u = u

So u = 2m

Therefore, the 7.00-m-long baby blue whale must be placed 2.00 m in front of the concave mirror with a focal length of 30.0 m to get a real image the size of a mature blue whale.