7 Facts On Force Of Gravity On Slope: What, How, Impacts


You must have observed that the speed of the object increases when it is sliding down the slope. Does this happen because of the force acting on the object due to gravity on slope?

The speed of the object on the slope is determined by two main forces. The very first thing is the steepness of the slope and the second and most important is the force acting by the object against the slope which is the force due to gravity.

What is gravity on slope?

The force due to gravity always acts downward towards the center of the Earth.

The gravity is the same at the plane ground and even on the slope irrespective of the steepness of the slope but only the magnitude of the force due to gravity varies.

If the object is on a gentle slope then the acceleration of the object down the slope will be less as compared to the speed acquired by the object while rolling down the slope from the steeper hill. This is because the magnitude of the force due to gravity on the object accelerating down from the steeper slope is more as compared to the gentle slope.

What is force of gravity on slope?

The force of gravity on the slope is the push force acting against the ground by the object due to its weight.

The force of gravity on a slope is always the same for the object having a mass ‘m’ wherever the object is present. The force of gravity on the object is always constant because its mass and the acceleration due to gravity value is constant and is equal to F=mg

Work Done by Gravity on an Incline

The work done is defined as the force required to displace the object from its initial place and is given by Work=Force*times displacement

In the case of the object moving on an inclined plane, the work is done by the force of gravity to displace the object from a certain height above the ground on the inclined plane.

Suppose there is an object of mass ‘m’ accelerating down from the inclined plane as shown in the figure below:-

gravity on slope
Different forces acting on the block sliding down on an inclined plane

The force due to gravity which is acting against the slope is equal to Fg=mg. Due to the gravity force, the object is moving down the slope with the force F=mgSinθ

The frictional force [latex]f_k=\mu N [/latex]

is acting against it to resist the acceleration of the object which results due to the parallel force exerted against the normal force N of the object which is [latex]F_{//}=mgCos\theta [/latex].

The displacement of the object from the inclined plane is ‘h’ which is the height of the object from above the ground. Hence the work done by the object is

W=mgh

The force due to gravity is exerted on the object to bring it down on the plane surface of the Earth accelerating it down the slope.

When force of gravity on inclined plane is maximum?

The force of gravity is the same at any point on the inclined plane because the mass and the acceleration due to gravity remain unvaried.

The force due to gravity is acting infront of the object while it is accelerating down the slope, the magnitude of the gravity of force will be greater if the slope is steeper.

The force that holds the object on the ground is the force acting against the normal force on the ground by the object which is –mgCosθ and the component of the force responsible for accelerating the object down is the slope is mg Sinθ.

This follows Newton’s second law of motion

F=ma

And hence the acceleration of the object from the slope is equal to

a=F/m

The maximum force acting on the object is mgSinθ, hence

What affects gravitational force on inclined plane?

The angle of the slope with the ground determines the speed of the object and the magnitude of the force that pushes it downward.

As the object is on an inclined plane, it is raised above the ground level gaining the potential energy thus the gravitational pull decreases slightly. But due to unbalance forces the object accelerates down.

If the angle between the direction of the force of gravity and the slope becomes lower, then the object will push down towards the ground. The center of gravity of the object is where the entire weight of the body is concentrated and tends to keep the object in the equilibrium position of rest.

Does gravitational force change with angle?

The gravitational force exerted on the object is constant and always acts towards the center of the Earth.

For an object on an inclined plane, the gravitational force on the object remains the same but only the magnitude of the parallel force acting on the object on the slope increases with the slope.

From the below diagram we can see that different forces are acting on the object but the direction of the two forces are in the same direction. If the angle φ increases, then the magnitude of these forces increases and the object will accelerate down the slope at high speed.

The parallel force pushing the object down the slope

The parallel force is created due to the force exerted on the ground due to the normal force and the force due to the center of gravity of the object making an angle φ acting parallel to the direction of the slanting force mgSinθ push the object down the slope as the magnitude of the force in this direction increases.

How to calculate force of gravity on an incline?

The net forces acting on the object on an inclined plane is the sum of the force of gravity, perpendicular force, and parallel force.

The force of gravity of the object on a slope is always acting downward and according to Newton’s second law of motion, the force of gravity on the object is equal to mass times the acceleration due to gravity i.e. Fg=mg

Now, let us see how to calculate the net force of gravity on the object on an incline plane step by step:-

Angle of Inclination

The very first thing is to find the inclination angle of the slope that determines the magnitude of forces and the speed of the object.

Mass of the Object

Secondly, you should know the mass of the object. If you know the normal force of the object then you can calculate the mass by using the formula:- m=F/a

Find Force due to Gravity

The force due to gravity is always directed towards the center of gravity of the Earth and is equal to mg.

Find the Perpendicular Force

This is a force acting in the direction of acceleration of the object and responsible for the motion of the object down the slope and is equal to

Find the Parallel Force

This is the force generated due to the effect of gravity and the force developed in response to the normal force against the slope of the hill and adds to the pushing force on the object that drags it down the slope and is equal to

Calculate the Frictional Force

This is the force acting against the velocity of the object by resisting its motion and depends upon the coefficient of friction of the slope that determines the roughness of the ground and is given as

and is related to the normal force of the object acting on the ground.

Find the Net Force

The force that is responsible for the object accelerating down the slope is the parallel force and the frictional force is opposing the acceleration of the object acting in opposite direction. The normal force is equal to the perpendicular force acting on the object.

Using this you can then find the acceleration of the object from the inclined plane by using Newton’s second law of motion equation.

F=ma

Hence, the acceleration of the object from the inclined slope is

a=Fnet/m

What is the acceleration of the object of mass 2kg sliding down from the inclined place with an inclination angle of 300 having a coefficient of friction of 0.15?

Given: m =2kg

θ=300

μ=0.15

The force due to gravity is

The parallel force component is

The perpendicular force is

The force due to friction is

Hence, net force on the object is

Therefore the acceleration of the object is

The acceleration of the object from the inclined plane is 7.75m/s2.

Summary

The force of gravity on the object remains the same even on the inclined plane. The force which is responsible for the acceleration of the object down the slope is the parallel force exerted on the object due to the force of gravity from the center of its mass point in front and the perpendicular force.

AKSHITA MAPARI

Hi, I’m Akshita Mapari. I have done M.Sc. in Physics. I have worked on projects like Numerical modeling of winds and waves during cyclone, Physics of toys and mechanized thrill machines in amusement park based on Classical Mechanics. I have pursued a course on Arduino and have accomplished some mini projects on Arduino UNO. I always like to explore new zones in the field of science. I personally believe that learning is more enthusiastic when learnt with creativity. Apart from this, I like to read, travel, strumming on guitar, identifying rocks and strata, photography and playing chess. Connect me on LinkedIn - linkedin.com/in/akshita-mapari-b38a68122

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