(a) A 4.97 kg salami is supported by a cord that runs to a spring scale, which i
ID: 582337 • Letter: #
Question
(a) A 4.97 kg salami is supported by a cord that runs to a spring scale, which is supported by another cord from the ceiling (see Figure (a)). What is the reading on the scale, which is marked in weight units? (b) In Figure (b) the salami is supported by a cord that runs around a pulley and to a scale. The opposite end of the scale is attached by a cord to a wall. What is the reading on the scale? (c) In Figure (c) the wall has been replaced with a second 4.97 kg salami on the left, and the assembly is stationary. What is the reading on the scale now?
Explanation / Answer
In all three cases ( a to c ), the scale is not accelerating. This implies that the two cords exert forces of equal magnitude on it. The scale reads the magnitude of either of these forces.
In all cases, the tension force of the cord attached to the salami must be the same in magnitude as the weight of the salami.
Thus, the scale reading is
W = mg
W = ( 4.97 kg ) ( 9.8 m/s2)
W = 48.7 N
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