Guys, please help me with this physics doubt? :(

[DC1313]

http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Physics (0625)/0625_s03_qp_3.pdf

Question 7 part c)i) how do you do it?
The mark scheme: http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Physics (0625)/0625_s03_ms_1+2+3+5+6.pdf

It says: Source and receiver arranged.
The source could be a gun or anything labelled source right?
But what is the receiver?!? Is it a human? or a sensor? LOL because later on it says record time between flash and bang. a machine cant do that, it can just record one input. i guess.

SOOO what is the receiver? Do we just draw a block and label it receiver? >.<

 

[Hamzeh S]

oh my teacher taught me this one last year you just need to draw 2 students with a distance measured between them one student with a stop watch and the other one with a device that generates light and sound at the same time and then the student with the stop watch must start the stop watch when he sees light since light travels faster than sound and the distance draw a meter rope or anything it must be a measured distance and then use the formula v = d/t i added some extra info just draw it its simple