A train left the station at 9:00am. The next stop was 629 km south. It arrived at 2:00pm the same day. What was its speed?

Explanation:

We need to calculate the time it had travelled first:

9:00 to 12:00 = 3 hours.

12:00 to 2:00 = 2 hours

Total travel time = 5 hours.

The formula for speed is distance ÷ time (Hence, the unit for speed is m/s, kph, mph, etc.)

= 629km ÷ 5 hours

= 125.8 km/hour ~ 125.8kph

it's when something is going so fast it makes a loud noise, breaking the sound barrier, for example: a jet makes a loud noise, not only cause of the jet but because they reached a point where they went so fast that you can year the noise from various parts, kinda like a police car, lets say the car was going   so fast that you hear the siren of the cop car right next to you, but the car is probably a mile a way, it's cos the siren was next to you a few seconds if you understand me