Cart is set rolling across a level table, at the same speed on every trial. if it runs into a patch of sand, the cart exerts on the sand an average horizontal force of 6 n and travels a distance of 6 cm through the sand as it comes to a stop. if instead the cart runs into a patch of flour, it rolls an average of 18 cm before stopping. what is the average magnitude of the horizontal force the cart exerts on the flour? 2 n

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?