A spring scale is used to measure the weight of travel bags at the airport. A weight of 15n causes its spring to extend by 3cmFormula 1( force =elastic constant k × extension x)Formula 2( weight w =mass m × gravity g), where value of g =x10 m/ s2

Convection currents are caused by differences in what two things?

State the below theories and give the name of the writer of the theory 1. wave theory 2. quantum theory 3. corpuscular theory 4. electromagnetic theory

You have two photos of a person walking. one shows the person at the corner of third and main streets, the other shows the person at the corner of tenth and main streets. there are lampposts at every corner in this town, and the first picture shows it to be 10: 32: 00 exactly. the second picture shows it to be 10: 49: 30. you know three facts: (1) all of the clocks are synchronized; (2) there are exactly 12 equal-sized blocks per kilometer in this town; and (3) the streets that cross main in this area are numbered consecutively, with no interruptions. what is the person’s average speed in kilometers per hour?