5. (serway 9th ed., 7-3) in 1990, walter arfeuille of belgium lifted a 281.5-kg object through a distance of 17.1 cm using only his teeth. (a) how much work was done on the object by arfeuille in this lift, assuming the object was lifted at constant speed? (b) what total force was exerted on arfeuille’s teeth during the lift? (ans. (a) 472 j; (b) 2.76 kn)

Ais useful when you need a simple machine to you separate two things. a. lever b. screw c. pulley d. wedge

While studying chemical reactions and conservation of matter, sarah's class conducted a variety of experiments. sarah and her lab partner found the mass of a wax candle and placed the candle in a flask. the students lit the candle and let it burn to completion. all that was left was wax and charred candle wick. per their teacher's instructions, the students found the mass of the products. their data can be seen in the data table. formulate a hypothesis the students could test to explain why the experiment did not support the law of conservation of matter. a) the students could repeat the experiment using different candles; there might have been a flaw in the candle. b) the experiment should be repeatable. the students should run several trials and then take an average of the after mass in each trial. c) the students should have someone in the class check their measurement skills as they repeat the experiment. they may have made an error using the balance. d) the students should burn the candle in a container that has some type of lid so that any gas that is a product of the reaction can be contained and massed. submit

What is the primary force that suspension bridges use cables to hold their spans up? a. tension force b. resistance force c. normal force d. elastic force e. applied force