A body of mass m is pulled by a rope which makes an angle with horizontal. The coefficient of friction between body and ground is u then tension on rope to make the body just to move is umg (b)

d) physical means can be used to separate the components of air.

that tool is called an altimeter which measures your altitude which can be used to tell which atmosphere you are currently in, including the stratosphere.

hope this ! : )

the answer is f1 and d2 because if you put equal force on those two points the beam would balance trust me on this