Question

plzz answer this subject science for class 10

Answer 1

1/f=1/v+1/u
As it is a concave mirror, f=-15
u=-40
1/(-15)=1/v+1/(-40)
-1/15+1/40=1/v
(-8+3)/120=1/v
-5/120=1/v
-1/24=1/v
v=-24

When the object is displaced through a dist of 20cm towards the mirror
u=40-20=20
1/f=1/v+1/u
1/(-15)=1/v+1/(-20)
-1/15+1/20=1/v
(-4+3)/60=1/v
-1/60=1/v
v=-60

-60-(-24)=-36cm

The image distance displaces by 36cm away from the mirror.