No one has been there yet
        
             
        
        
        
Answer:
using the lens formula: 1/f = 1/u + 1/v
focal length f = -30 (negative because it is concave lens)
object distance u = 60
image distance v= unknown
1/-30 = 1/60 + 1/v
v = -20
So, the image is 20cm from lens (on the same side along with the object), and it is virtual (because of negative sign) and erect (concave lens must produce erect images).
 
        
             
        
        
        
Answer:
D, rubber
Explanation:
Metals have free electrons, and are very bad as insultators. Metals conduct electricity very well. On the other hand, rubber has no free electrons and does not conduct electricity very well
 
        
                    
             
        
        
        
Answer:
Part a)

Part b)

Part c)

Part d)

Explanation:
Part a)
As we know that speed of package is same as that of helicopter in horizontal direction
So after time "t" the velocity in x direction will remain constant while in Y direction it will go free fall
So we have



Part b)
Distance from helicopter is same as the distance of free fall
so we will have

Part c)
If helicopter is rising upwards with uniform speed
then final speed of the package after time t is given as


Part d)
distance from helicopter
