Aprimitive space heater consists of a 10.0 cm radius iron ball through which electrical current was passed in order to heat the ball, and subsequently the surrounding air. if the temperature of the iron ball is kept at 510 k, and the room temperature is 20oc, what power is radiated into the room? assume the ball is a perfect blackbody.
a. 110w
b. 480w
c. 140w
d. 430w

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?