A 1.0 kg ball hangs motionless from the ceiling by a light string. Four students list the forces acting on the ball.
Which list is correct?
a) Tension upward and weight downward; no other forces
b) Only its weight acting downward; no upward force because the ball is at rest
c) Tension upward, weight downward, and an additional upward inertial force balancing the weight
d) Weight downward, tension upward, and a downward reaction force exerted by the ceiling on the ball