a green bead of mass 70 g slides along a straight wire. The length of the wire from point "A" to point "B" is 0.700 m, and point "A" is 0.400 m higher than point "B". A constant friction force of magnitude 0.020 0 N acts on the bead. If the bead is released from rest at point "A", what is its speed at point "B" ?