Answer:
T = 35.4 + 3.60t
Substitute the time in seconds to get the value for t.
Explanation:
Since the box has a velocity function V(t) which changes with time the box is accelerating
a= dv/dt = 2.00 + 1.20t (obtained by differentiating with respect to t.)
There are two forces acting on the box which are the tension in the string and the weight of the string mg.
From Newtown's second law,
T – mg = ma
T = ma + mg
Substituting the value for a into the equation,
T = m(2.00 + 1.20t + 9.8)
= m(11.8 + 1.20t)
Given m = 3.00kg
T = 3(11.8 + 1.20t)
= 35.4 + 3.60t