a train traveling at 72 km/h crosses a platform in 30 seconds what is the length of the platform in meters

Three archers each fire four arrows at a target. joe’s four arrows hit at points 10 cm above, 10 cm below, 10 cm to the left, and 10 cm to the right of the center of the target. all four of moe’s arrows hit within 1 cm of a point 20 cm from the center, and flo’s four arrows hit within 1 cm of the center. the contest judge says that one of the archers is precise but not accurate, another archer is accurate but not precise, and the third archer is both accurate and precise. which description applies to which archer? explain

How is sound energy produced a. vibrating objects b. objects being heated c. temperature differences d. stationary objects

Air is contained in a variable-load piston-cylinder device equipped with a paddle wheel. initially, air is at 400 kpa and 17°c. the paddle wheel is now turned by an external electric motor until 75 kj/kg of work has been transferred to air. during this process, heat is transferred to maintain a constant air temperature while allowing the gas volume to triple. calculate the required amount of heat transfer in kj/kg.