Question

It takes 10 seconds to send or read an SMS text message. An earthquake hits me. I want to warn my friend who is located 60 km due west of me. The earthquake epicentre was 25 km due south of me. How many seconds does my friend have to get out of the building after reading my SMS? Assume SMS transmission time is instantaneous. Assume earthquake waves go at 1 km/s.

Answer 1

Answer:

20 sec

Step-by-step explanation

Distance from epicenter to friend = 65 km

time it takes for earthquake to reach me = 25 sec

time is takes to send + read text message = 10+10 sec= 20 sec

time it takes for earthquake to reach friend = 65 sec

time left = 65-(25+20) = 20 sec