Xét một cái hộp trượt có ma sát trên một bề mặt nằm ngang. nếu hệ là bề mặt nằm ngang thì hệ là a) không cô lập
b) cô lập
c) không thể xác định được

Hydrogen and helium are both members of?

Why is the energy that results from a roller coaster's position at the top of a hill referred to as potential energy?

Aboat radioed a distress call to a coast guard station. at the time of the call, a vector a from the station to the boat had a magnitude of 45.0 km and was directed 15.0° east of north. a vector from the station to the point where the boat was later found is = 30.0 km, 15.0° north of east. what are the components of the vector from the point where the distress call was made to point where the boat was found? in other words, what are the components of vector c = b - a?