Aporter carries a 25 kg suitcase a distance of 1 km. explain why the porter does no work

Abaseball picther can throw a ball at about 90 miles per hour, v = 40 m/s, on solid rock ground. we now put him into space. when he throws the ball, which weighs mb = 0.15 kg moves away from himat the same speed. how long does it take the ball thrown in space to travel the 30 meters to the batter? he weighs mp = 100kg

Asun-sized star will spend most of its lifetime as a: white dwarf red giant protostar main-sequence star

The earth is constantly spinning on its axis, like you might spin a basketball on your finger. it is this spinning of the earth that causes