The force the box is exerting on Manuel is the weight of the box, downward:

and this force is perfectly balanced by the constraint reaction applied by Manuel's hand, pushing upward.
<span>an apparatus for producing gas, steam, or another product. here is what it means sorry if i couldn't help. </span>
If<span> The </span>Sun<span> Went Out, How Long </span>Could<span> Life On </span>Earth<span> Survive? ... (which is actually physically impossible), the </span>Earth would stay<span> warm—at least ... from the planet's core </span>would<span> equal the</span>heat<span> that the </span>Earth<span> radiates into space, ... Photosynthesis </span>would<span> halt immediately, and </span>most<span> plants</span>would<span> die </span>in<span> a few </span>weeks<span>.</span>
Answer:
False statement = There must be a non-zero net force acting on the object.
Explanation:
An object is moving at a constant speed along a straight line. If the speed is constant then its velocity must be constant. We know that the rate of change of velocity is called acceleration of the object i.e.

a = 0
⇒ The acceleration of the object is zero.
The product of force and acceleration gives the magnitude of force acting on the object i.e.
F = m a = 0
⇒ The net force acting on the object must be zero.
So, the option (a) is not true. This is because the force acting on the object is zero. First option contradicts the fact.