We are given a box that slides up a ramp. To determine the force of friction we will use the following relationship:

Where.

To determine the Normal force we will add the forces in the direction perpendicular to the ramp, we will call this direction the y-direction as shown in the following diagram:
In the diagram we have:

Adding the forces in the y-direction we get:

Since there is no movement in the y-direction the sum of forces must be equal to zero:

Now we solve for the normal force:

To determine the y-component of the weight we will use the trigonometric function cosine:

Now we multiply both sides by "mg":

Now we substitute this value in the expression for the normal force:

Now we substitute this in the expression for the friction force:

Now we substitute the given values:

Solving the operations:

Therefore, the force of friction is 15.01 Newtons.
Diamonds and iron, as they can't be easily put back or recreated. Remember to make sure yourself.
Hope this helps :)
Answer:
sofa
Explanation:
because the sofa is heavy and the amount of friction is high due to the amount of opposite friction is pushing it back
Answer:
45000cm2(cuarenta y cinco mil centimetros al cuadrado).
Explanation:
porque el volumes es igual a el área de la base por la altra
Using
F= mv²/r
4 = 0.5×v² / 2
8 /0.5 = v²
v²=16
v= √16
v= 4 ms-¹