2nd Law: F, m, a Relationship
Unbalanced forces cause objects to accelerate:
ΣFnet = ma
Fnet = Resultant Force
Mass lifted upwards
T - mg = ma
T = m(g + a)
Mass accelerated downwards
T = m(g - a)
Two Masses Connected by a String
When two masses (A and B) are connected:
Top String (TA):
TA = mAg + mBg
Bottom String (TB):
TB = mBg
Conceptual Check
"Which cart is slowing down as it travels to the right?"
Answer: Choice 2