A100 n box sits on a 30 degree incline. the magnitude of the normal force acting on it is: a. none of these
b. 87 n
c. 100 n
d. 50 n

b. 87N

Explanation:

Start by looking at the picture I attached you. As you can see in the diagram of the left, the weight=mg has one component in the x-axis and another in the y-axis. The normal force is directly over the y-axis, so we dont have to worry about the forces on the x-axis. Now, take a look at the diagram of the right, using it, we will be able to find the weight over the y-axis with trigonometry identities:

Now applying  newton's second law:

There is no acceleration in this case, so a=0

Solving for N:

none, its a machine

3. dark matter

empty space could also be a simple vacuum