The continental crust
Hope it helps!!
Answer:
1. increases
2. increases
3. increases
Explanation:
Part 1:
First of all, since the box remains at rest, the horizontal net force acting on the box must equal zero:
F1 - fs = 0.
And this friction force fs is:
fs = Nμs,
where μs is the static coefficient of friction, and N is the normal force.
Originally, the normal force N is equal to mg, where m is the mass of the box, and g is the constant of gravity. Now, there is an additional force F2 acting downward on the box, which means it increases the normal force, since the normal force by Newton's third law, is the force due to the surface acting on the box upward:
N = mg + F2.
So, F2 is increasing, that means fs is increasing too.
Part 2:
As explained in the part 1, N = mg + F2. F2 is increasing, so the normal force is thus increasing.
Part 3:
In part 1 and part 2, we know that fs = Nμs, and since the normal force N is increasing, the maximum possible static friction force fs, max is also increasing.
let Coefficients of Friction of Rubber on asphalt (dry) =0.7
F= Coefficients of Friction * normal force = 0.7 * 60 =42 N
so the net force of the rubber is zero, meaning it will travel at a constant speed.
When the rubber is travel at 2m/s, 42N is required to keep moving at constant speed
