Question

Two boxes, P and Q, are at rest on a frictionless horizontal surface. A light, flexible cord connects them. The mass of P is greater than the mass of Q.
(As shown in the diagram,) A horizontal force of magnitude F is applied to box Q, causing both boxes to accelerate to the right.
What best describes the magnitude of the force exerted by the connecting cord on box P?

*equal to F
*greater than F
*zero
*less than F, but greater than zero

Answer 1

The boxes are tied together, so their motions are equal ... displacement, velocity, and acceleration ... the same for both boxes once they get going.

The force (F) exerted on Q has to be enough to accelerate the mass of both boxes.

But the force of the string pulling box-P is only enough to move the mass of box-P with the same acceleration.

So the magnitude of the force exerted on box-P by the string (the tension in the string) is less than F , (but greater than zero, because it accelerates box-P).

It doesn't matter which box is heavier, lighter, more mass, or less mass.

Answer 2

the answer is less than F, but greater than zero