Motion and Gravity


Acceleration due to Gravity

We already found the value of acceleration due to gravity using the following equation.

g = 𝑮 /m/𝑹𝟐

where, ‘G’ is the universal gravitational constant, ‘M’ is the mass of the earth, and ‘R’ is the earth’s radius. From the above relation it’s quite interesting to note that the acceleration due to gravity is not dependent on the object’s mass but on the mass of the earth. This means that the acceleration due to gravity is independent of the object’s mass.

Suppose a stone and a paper are thrown at the same from some height then both the objects will hit the floor at the same time. But this is true in case of perfect vacuum. In other cases, the wind resistance also comes into play.

What is the effect of resistance on falling objects?

Consider a stone and a paper dropped at the same time from a building. You will find that the stone will hit the ground first. When objects fall towards the ground, the air offers resistance to them in the upward direction. As the resistance offered to the paper is more, it takes more time to reach the ground.

Effect of Air Resistance

Effect of Air Resistance

Equations of Motion

We already know the three equations of motion ,

𝒗 = 𝒖 + 𝒂𝒕

𝒔 = 𝒖𝒕 +𝟏/𝒂𝒕𝟐/𝟐

𝒗𝟐 = 𝒖𝟐 + 𝟐𝒂𝒔

u – Initial velocity v – Final Velocity

a – acceleration s – Distance or Displacement covered in time t

Now, in case of objects falling under the influence of gravity, the above equations can be

modified by replacing ‘a’ with ‘g’.