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the objects described here in static equilibrium, dynamic
Chapter 18, Problem 2CQ(choose chapter or problem)
the objects described here in static equilibrium, dynamic equilibrium, or not in equilibrium at all? a. A girder is lifted at constant speed by a crane. b. A girder is lowered by a crane. It is slowing down. c. You’re straining to hold a 200 lb barbell over your head. d. A jet plane has reached its cruising speed and altitude. e. A rock is falling into the Grand Canyon. f. A box in the back of a truck doesn’t slide as the truck stops.
Questions & Answers
QUESTION:
the objects described here in static equilibrium, dynamic equilibrium, or not in equilibrium at all? a. A girder is lifted at constant speed by a crane. b. A girder is lowered by a crane. It is slowing down. c. You’re straining to hold a 200 lb barbell over your head. d. A jet plane has reached its cruising speed and altitude. e. A rock is falling into the Grand Canyon. f. A box in the back of a truck doesn’t slide as the truck stops.
ANSWER:Solution: A.object in static equilibrium do not move remains at rest.the object also cannot move in our frame of reference.a girder is lifted at constant speed by a crane is in dynamic equilibrium,because the girder motion is not acceleration,the net force on it must be zero.therefore the tension and weight must be in equilibrium in magnitude and opposite in direction. B.a girder is lowered by crane means it is not in equilibrium state,because the girder is slowing down, its acceleration is in the opposite direction from its motion.therefore the net force on girder is upward and tension i