Answer:
<h3>Ion beams and Electrochemical are two examples of direct current electricity.</h3>
CORRECT ANSWER:
a- Cell-surface receptors bind polar signaling molecules; intracellular receptors bind nonpolar signaling molecules.
STEP-BY-STEP EXPLANATION:
The complete question from book is
According to Figure 9.6, what is a key difference between cell signaling by a cell-surface receptor and cell signaling by an intracellular receptor?
a- Cell-surface receptors bind polar signaling molecules; intracellular receptors bind nonpolar signaling molecules.
b- Signaling molecules that bind to cell-surface receptors lead to cellular responses restricted to the cytoplasm; signaling molecules that bind to intracellular receptors lead to cellular responses restricted to the nucleus.
c- Cell-surface receptors bind to specific signaling molecules; intracellular receptors bind any signaling molecule.
d- Cell-surface receptors typically bind to signaling molecules that are smaller than those bound by intracellular receptors.
e- None of the other answer options is correct.
The ball is using an reaction and opposite reaction, so when you dribble a basketball you push the ball with downward force and the ground pushes the ball back up thus making the opposite reaction.
According to Newton's second law, the resultant of the forces acting on the box is equal to the product between its mass and its acceleration:

(1)
we are only concerned about the horizontal direction, so there are only two forces acting on the box in this direction:
- the horizontal component of the force exerted by the rope, which is equal to

- the frictional force, acting in the opposite direction, which is equal to

By applying Newton's law (1), we can calculate the acceleration of the box:

Net force = mass x acceleration = 250 x 3 = 750 N