A concave mirror with a radius of 20 cm creates a real image 30 ...

[folubunmi]

A concave mirror with a radius of 20 cm creates a real image 30 cm from the mirror. What is the object distance?
 
  A)
 
  50 cm
  B)
 
  20 cm
  C)
 
  15 cm
  D)
 
  7.5 cm
  E)
 
  5.0 cm

Question 2

You want to insert an aluminum rod, which at 20C has a radius of 1.00020 cm into a copper tube which has a radius of 1.00010 cm at the same temperature.
 
  You decide to put both of them in the refrigerator. At what temperature will the rod just fit if both are cooled to the same temperature? The coefficient of thermal expansion for aluminum is 2.4  10-5K-1, and that of copper is 1.7  10-5K-1.
  A)
 
  7.8C
 
  B)
 
  6.3C
 
  C)
 
  9.2C
 
  D)
 
  14.7C
 
  E)
 
  5.7C

[parker125]

Answer to Question 1

C

Answer to Question 2

E

[folubunmi]

Both answers were spot on, thank you once again

[parker125]

Great! Please up vote