A man stands in front of a large plane mirror as shown in the figure. How far must he walk before he is 5 m away from his image?
A. 7.5 m
B. 8.5 m
C. 7.5 cm
D. 7 m
Answer:A
A man stands in front of a large plane mirror as shown in the figure. How far must he walk before he is 5 m away from his image?
A. 7.5 m B. 8.5 m C. 7.5 cm D. 7 m
Explanation: As the distance between the man and the mirror is 10 m, the distance between man and his image is 10 + 10 or 20 m, as image distance and object distance are equal. Distance between the man and his image is 5 m when the man is 2.5 m away from the mirror. Therefore, the man has to walk 10 m – 2.5 m = 7.5 m towards the mirror.