Calculation of Image Speed:
- The speed of an image formed by a concave mirror is given by the formula:
Image Speed = - (magnification) x (object speed)
- The magnification (m) of an image formed by a concave mirror can be calculated using the formula:
m = - (image distance) / (object distance)
- Given that the object distance (u) is 9 m and the focal length (f) is 1 m, we can calculate the image distance (v) using the mirror formula:
1/f = 1/v + 1/u
1/1 = 1/v + 1/9
v = 9/10 = 0.9 m
- Now, we can calculate the magnification:
m = -0.9 / 9 = -0.1
- Substituting the magnification and object speed (5 m/s) into the image speed formula:
Image Speed = -(-0.1) x 5 = 0.5 m/s

Explanation of Average Speed:
- The average speed of the image can be calculated by using the total distance travelled by the image and the total time taken.
- Since the image is moving towards the mirror, the distance travelled by the image is the sum of the object distance (9 m) and the image distance (0.9 m), which is 9.9 m.
- The time taken for the image to travel this distance can be calculated using the formula:
Time = Distance / Speed
Time = 9.9 / 0.5 = 19.8 s
- Therefore, the average speed of the image is the total distance travelled (9.9 m) divided by the total time taken (19.8 s), which is:
Average Speed = 9.9 / 19.8 = 0.5 m/s