How fast do the objects fall?

 How fast do the objects fall? 

          When we throw a ball up in the air, we observe that it gradually slows down, and then almost comes to a stand still, before it starts falling back to the ground. While falling down, it should be noted that the initial speed is low but gradually becomes high. 

          The Earth attracts all objects towards its centre with a force known as the force of gravity. The ball falls to the ground due to this force of gravity. The force of gravity makes all falling objects acquire an acceleration, which is called the acceleration due to gravity. It is denoted by 'g'. 

          The acceleration due to gravity accelerates the ball roughly at 9.8 metres per second per second (32 feet per second per second). This means that each second the object would move 9.8 metres faster than the previous second. The speed of the ball at different intervals of time varies as follows. 

          To begin with, the ball or a falling object is stationary or its speed is zero. At the end of 1 second, it travels 9.8 metres per second. At the end of 2 seconds, it moves 19.6 metres per second, and at the end of 3 seconds, 29.4 metres per second and so on. In fact, every second, the object falls 9.8 metres per second faster than its speed in the previous second.

           Acceleration due to gravity is defined as the rate of change in velocity of a falling object with respect to time due to the force of gravity. Because it is a measure of 'rate of change of velocity', it is expressed in metres per second per second, and is termed as 'metres per second square'.

            The acceleration of a body or object falling freely in vacuum varies slightly from place to place due to slight variation in the gravitational force of the Earth, as the distance of the place from the centre of the Earth varies. In London, the value of 'g' is 9.807 metres per second per second, at North Pole 9.8 metres per second per second, and at the equator it is 9.79 metre per second per second. At sea level in Washington, it is 9.8008 metres per second per second. 

            One of the important points to note about falling objects is that however heavy they might be, they all fall at the same rate. But, air resistance may retard the speed of falling objects. The famous scientist Galileo demonstrated this fact by dropping a heavy cannon ball and a light musket ball at the same time from the Leaning Tower of Pisa. Both the objects hit at the ground at the same time. 

            Air resistance is the main reason why some objects fall slower than others. A feather, for example, floats slowly downwards because it faces more air resistance due to its relatively large surface area. A smooth, pointed bullet will fall faster than a feather because it experiences less air resistance. In vacuum both objects will fall at the same speed, as there would not be any air resistance.