A box of mass 60 kg is at rest on a horizontal floor that has a static coefficient of friction of 0.6 and a kinetic coefficient of 0.25 a)The minimum force necessary to start moving the box
b) The friction force and the acceleration of the box if a horizontal force of 400 N is applied

a) F = 353.2 N

b)

   a = 4.21 m/s²

Explanation:

a) The minimum force necessary to start moving the box s given by:       

Where:

F: is the force applied to move the box

μs: is the static coefficient of friction = 0.6          

m: is the mass = 60 kg

g: is the gravity = 9.81 m/s²

b) The acceleration is:

Now, the friction force is:

I hope it helps you!    

porque la cantidad de gases de efecto invernadero alcanzó un nuevo máximo sin precedentes, causando daños muy graves a esta, por eso es importante monitorearla, para controlar el porcentaje de daños que esta causa y poder reducirlo o mantenerlo.

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.