If an object is moving in a circle at constant speed, what does newton’s second law inform us about the motion? 1. xf = 0 since v for the object is constant. 2. xf points in the opposite direction to the object’s velocity. 3. xf points in the direction the object is moving. 4. xf points directly outward, away from the center of the circle. 5. xf points toward the center of the circle.

This situation is characteristic of the uniform circular motion (figure attached), where is the velocity vector, whose direction is perpendicular to the radius of the trajectory.

The other thing that can be observed is that its acceleration is directed toward the center of the circumference (that's why it's called centripetal acceleration).

Now, according to Newton's 2nd law, the force is directly proportional and in the same direction as the acceleration:

Therefore the net force XF resulting from the movement points towards the center of the circle and is called Centripetal Force.

Therefore the correct option is 5.

air exerts forces on falling objects near earth’s surface.

explanation:

the term 'free falls' refer to object that are falling towards the earth, in a situation in which gravity is the only force acting on the object.

for an object in free fall, the acceleration is constant (g, the gravitational acceleration), and so the velocity of the object constantly increases.

for objects near earth's surface, there is always another force acting on the object: the resistance due to the air. this force is opposed to the direction of fall of the object, and it is proportional to the velocity of the object, so as the object falls down, this force increases up to a point when it balances the force of gravity, and the object continues its motion at constant velocity (called terminal velocity). since in this case gravity is not the only force acting on the object, we are not in a situation of free fall.