Question

question 2 (1 point)
an object of mass m is hanging by a string from the ceiling of an elevator. the elevator is moving upward, but slowing down. what is the tension in the string?
less than mg
exactly mg
greater than mg
zero

Explanation:

1. First, analyze the motion of the elevator: The elevator is moving upward but slowing down, so its acceleration is downward.

• For the object of mass \( m \) hanging in the elevator, we apply Newton's second law. The forces acting on the object are the tension \( T \) upward and the weight \( mg \) downward.
• Newton's second law in the vertical direction is \( F_{net}=ma \), where the net force \( F_{net} = mg - T \) (taking downward as positive because acceleration is downward).
• Since the acceleration \( a \) is downward (the elevator is slowing down while moving upward), \( a>0 \). So \( mg - T=ma \), which can be rearranged to \( T = mg - ma \).
• Since \( ma>0 \) (because \( m>0 \) and \( a > 0 \)), we have \( T=mg - ma

Answer:

A. less than mg