An object rests on an inclined surface thanks to the presence of static friction forces between the object and the surface.
The magnitude of the friction force that prevents the object from sliding is found to be 30 N.
Now, the angle that the surface makes with respect to the horizontal is increased, and the object is found to be still at rest.
The magnitude of the friction force that prevents the object from sliding is now ...
choices:
a) zero
b) larger than zero but smaller than 30 N
c) Equal to 30 N
d) Larger than 30 N
My ans: I think it should be greter than 30N so B
You are correct. The friction force between the object and the inclined surface depends on the angle of the incline. As the angle increases, the friction force required to keep the object from sliding also increases. Therefore, the magnitude of the friction force that prevents the object from sliding will be larger than 30 N. Hence, the correct answer is d) Larger than 30 N.
To determine the magnitude of the friction force that prevents the object from sliding when the angle of the surface is increased, we need to understand the conditions for static equilibrium.
When an object is at rest on an inclined surface, there are two main forces acting on it: the force of gravity (its weight) pulling the object downward and the normal force exerted by the surface perpendicular to the object.
In order for the object to remain in static equilibrium, the force of friction between the object and the surface must counteract the component of the weight of the object that is parallel to the surface.
The magnitude of the friction force is directly proportional to the normal force and can be calculated using the equation: friction force = coefficient of static friction * normal force.
The coefficient of static friction represents the interaction between the object and the surface, and in this case, it is assumed to be constant.
Given that the magnitude of the friction force preventing the object from sliding is initially measured as 30 N, we can conclude that the weight component parallel to the surface (which the friction force counteracts) is also 30 N.
Now, when the angle of the surface is increased, the weight component parallel to the surface also increases. As a result, the friction force needs to increase to counteract this larger weight component in order to keep the object at rest.
Therefore, the correct answer is (d) Larger than 30 N, indicating that the magnitude of the friction force preventing the object from sliding is greater than 30 N when the angle of the surface is increased.