There is a high-speed camera to take a picture of the moment when the bullet penetrates the apple. After zooming in, it is found that the distance between the front and back of the bullet image is about 1% - 2% of the length of the bullet in the exposure time. It is known that the flight speed of the bullet is about 500m / s, so it can be estimated that the exposure time of this picture is the closest () A) 10's negative third second B) 10's negative sixth second C) 10's negative ninth second D) 10's negative twelfth second Although this problem is completely solved, I can't understand the answer, so please do it and explain it yourself Where did the bullet come from when it was five centimeters long?

There is a high-speed camera to take a picture of the moment when the bullet penetrates the apple. After zooming in, it is found that the distance between the front and back of the bullet image is about 1% - 2% of the length of the bullet in the exposure time. It is known that the flight speed of the bullet is about 500m / s, so it can be estimated that the exposure time of this picture is the closest () A) 10's negative third second B) 10's negative sixth second C) 10's negative ninth second D) 10's negative twelfth second Although this problem is completely solved, I can't understand the answer, so please do it and explain it yourself Where did the bullet come from when it was five centimeters long?

This kind of topic, well, I'll be an expert
1) Multiple choice questions need to see the answers first
2) The four answers of ABCD tell us that this is a question of order of magnitude;
3) Common sense tells us that if we consider the order of magnitude, we can assume many conditions ourselves;
4) Assuming that the bullet is 1 meter long, it can hit the aircraft carrier. So it is still assumed that the length of the bullet is between 1cm and 10cm
5) 1% - 2% of the bullet length is 0.1cm ~ 2cm
6）.
7）.
8）.
9) OK, you can do 6, 7 and 8. The conclusion is that you should pay more attention to the problem than the condition
PS: only 5 points, too little