In the previous part, you determined the maximum angle that still allows the crate to remain at rest. If the coefficient of friction is less than 0.7, what happens to this angle? (Note that you can adjust the coefficient of friction by clicking on the More Features tab near the top of the window and then using the slider bar in the right panel.)

the angle must decrease to maintain balance and that the system remains motionless

Explanation:

In a system of a block in an inclined plane, using Newton's second law

X Axis       Wₓ-fr = 0

Y Axis       N - = 0

The equation for the force of friction is

          fr = μ N

And using trigonometry for weight components

         sin θ = Wₓ / W

         cos θ = W_{y}/ W

         Wₓ = W sin θ

         W_{y} = W cos θ

We replace

         Wₓ = fr

         W sin θ = μ Wcos θ

         tan θ = μ

If the coefficient of friction decreases the force of static friction decreases, ₓso the value of the tangent must decrease so the angle must decrease to maintain balance and that the system remains motionless or with constant speed

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.