A boy is on a sled moving down a hill at 20 m/s. The combined mass of the sled and child is 100 kg. The momentum of the child and sled is
A. 5 kg. m/s
B. 20 kg. m/s
C. 1000 kg. m/s
D. 2000 kg. m/s

One hectometer is a) 1/1000 of a meter. b) 1/100 of a meter. c) 10 meters. d) 100 meters. e) 1000 meters.

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Agroup of student volunteers participates in a study designed to assess several behavioral interventions for improving output in a repetitive task. prior to the beginning of the study, all volunteers unknowingly observed, and their output is measured. at the beginning of the study, prior to any intervention, the volunteers perform the same task under the observation of a study administrator, and their overall output increases. which of the following terms describes this phenomenon? a. simpson's paradox b. hawthorne effect are d. novelty effect d. pygmalion effect e. observer-expectancy effect