An object slides down a inclined surface in the presence of kinetic friction forces.
At the given inclination the kinetic friction force is found to be of magnitude 90 N.
Now, the angle that the surface makes with respect to the horizontal is increased and the object continues to slide down the surface.
The magnitude of the new kinetic friction force present will be ... ?
I think that it should be smaller than 90N because if you think about it logically an increased angle would make the slope steeper, and things fall faster down steeper slopes which means that the friction force decreases; however i know that this is not really a valid explanation.
Could someone five a better explanation?
IF the angle is increased, the normal component of weight decreases, thus friction is less. Fricion= mg*mu*cosTheta.
If Theta increases, cosTheta decreases
To understand how the magnitude of kinetic friction force changes when the angle of the incline increases, we need to consider the factors that determine the friction force.
Kinetic friction force depends on two main factors: the coefficient of kinetic friction (μk) and the normal force (N) exerted on the object by the incline.
The coefficient of kinetic friction (μk) is a measure of the interaction between the object and the surface it slides on. It is a constant value that varies depending on the materials in contact. The normal force (N) is the perpendicular force exerted by the incline on the object and is proportional to the weight of the object.
When the angle of the incline increases, both the normal force and the gravitational force component parallel to the incline will also increase. If the mass of the object remains constant, the weight of the object will increase as well.
Based on this, we can consider two scenarios:
Scenario 1: The coefficient of kinetic friction remains constant.
If the coefficient of kinetic friction (μk) remains constant, and the weight of the object increases due to the increased angle of the incline, the normal force will also increase. As a result, the magnitude of the kinetic friction force will increase.
Scenario 2: The coefficient of kinetic friction decreases with increasing angle.
Alternatively, if the coefficient of kinetic friction (μk) decreases as the angle of the incline increases, the magnitude of the kinetic friction force will decrease. This can happen if the materials in contact have a decreasing coefficient of kinetic friction at higher angles.
Therefore, without more information about the specific materials in contact and their coefficient of kinetic friction, it is challenging to determine exactly how the magnitude of the new kinetic friction force will change when the angle of the incline increases.