Have spent hours poring over this homework question but am having difficulty getting the right process going to solve the problem. I don't really know where to start, and I'd really be grateful if someone could show me the ropes (pun intended ^_^). There are two components to the question.
(a) What is the tension force $T$ in the cables at this instant (Newtons)
(b) What is the net horizontal thrust force required to produce the truck's motion? This includes drive force from the wheels, rolling resistance and air resistance.
My (flawed, obviously) attempt at A went something like this:
Draw FBD for block A
Apply Newton's Second Law, where tension in cable is constant throughout its length $F_{y,A} = 2T-m_A\cdot g = m_A\cdot a_A$
Length of cord is constant, so $L = -2X_A+X_T + C$, and $-2a_A+a_T = 0$, so the acceleration of block A is $\frac{1}{2}a_T = 1.2\text{ m/s}^2$.
Rearranging equation from (2) provides $2T = m_A*g + \frac{1}{2}m_A\cdot a_T$, and then T = 456.5N.
Part B I struggle with altogether, because I don't have a clear process in my head to tackle the problem.
Edit~ A written attempt at a solution - Not sure how to factor in the angled a(T) as proposed...
TCos(b) = Tx = Ftx+Rair+Rrolling
- "plug and chug" $\endgroup$FA = 2*T.
The Tension in your rope would simply be FA/2 or 406.7N - Draw a FBD for each pulley and remember tension is the same throughout the cable $\endgroup$