Answer:
253 N
Explanation:
The forces acting on the box in the direction along the ramp are two:
- The component of the weight in the direction parallel to the ramp, , acting down along the ramp
- The force of static friction, , acting up along the ramp
The equation of motion along this direction is:
where:
m = 55.0 kg is the mass of the box
is the acceleration of gravity
is the angle at the base of the ramp
a is the acceleration of the box
However in this proble, the box is at rest, so the acceleration is zero:
Therefore, the equation becomes:
From which we find the static frictional force: