4. An object is being lifted to the top of building by a light inextensible rope with a tension of 20 N at an acceleration of 1.4 m/s2. Neglecting air resistance, calculate the object’s mass.

Answer 1

F = ma = 20 N.
m*1.4 = 20.
m = 20 / 1.4 = 14.3 kg.