Answer:
0.77 m/s^2
Explanation:
Notice that the weight of the 7 kg mass is calculated via:
weight = m * g = 7 * 9.8 N = 68.6 N
Since the tension in the string is larger (74 N), then the elevator is moving upward and the net force on the object is equal to:
74 N - 68.6 N = 5.4 N
Which tells us that the acceleration of the object is:
F = m * a
5.4 N = 7 kg * a
a = 5.4 /7 m/s^2
a = 0.77 m/s^2
and this must be the same as the acceleration of the elevator since object and elevator are moving together.
