Question

An object of mass m slides down an incline with angle. Which equation allows you to correctly calculate the normal force on the object?

Answer 1

Answer:

$N=mg cos \theta$

Explanation:

The normal force acting on an object is the force exerted by the surface on which the object lies on the object itself. Its direction is always perpendicular to the surface, while the magnitude of the normal force is equal to the force that the object applies on the surface perpendicular to it.

In the case of an object of mass sliding down, the normal force (N) is equal to the component of the weight of the object perpendicular to the surface of the incline, $W_{perp}$:

$N=W_{perp}$

By using trigonometry, the component of the weight perpendicular to the surface of the incline is:

$W_{perp}=mg cos \theta$

where m is the mass of the object, g is the acceleration due to gravity and $\theta$ is the angle of the ramp. Therefore, the normal force is:

$N=mg cos \theta$

Answer 2

Normal force is described as the force exerted on an object by gravity. Therefor, the normal force is mg, mass times gravitational force. However, as a product of the failure of our education system, this is taught differently in different schools. If normal force is described, where you're being taught, as the downward force, then it is mgsin(x), where x is the angle of inclination, so it's mass times gravitational force time the sin of the angle.