text: how much tension must a rope withstand ...? if it is used to accelerate a 1600 kg car vertically upward at 0.70 m/s^2> _____ n the tension in the rope is providing the upward force causing the accelerating.  first you need to find the net force acting on the object. net force = mass * acceleration. you are given the acceleration and mass, so this is easy to find.  but the rope does not just need to apply the net force, it must also apply enough additional force to counteract the objects weight.  the weight of the object, weight = mass * gravity  the overall tension in the rope, tension = mg + ma or the weight of the car + the net force acting on the car.