The weight of an object is zero at the center of the Earth because the gravitational force from all directions cancels out. At this point, the gravitational acceleration (g) is zero, meaning the object would experience no net gravitational force. At the Earth's surface, the value of 'g' is maximum, and the object experiences its full weight.

The attraction or fundamental interaction between the earth and an object or any two objects in the earth is known as Gravity.

Bound to the earth by gravity and due to friction with the earth surface and viscosity of multiple layers of air, atmosphere rotates with the earth constantly.

At the center of the earth the acceleration due to gravity is zero. Consequently, gravitational acceleration is greatest at earth's surface. Practically the maximum point of acceleration is in the Arctic Ocean, nearer to the coast of Greenland. 

Literally tension is the force that is transmitted through any object when it is pulled on both sides. In this perspective momenta is the tension between earth and its nearest objects.

Rockets are built to launch spaceship based on third law of motion of Sir Isaac Newton-To every action there is equal and opposite reaction. 

 Fathometer is an instrument that is often used for measuring the depth of the sea. It is generally attached beneath a ship or boat and sends echoes and sound waves to the basin of the sea and measures how long it takes for an echo to return for measuring the depth.

Hygrometer is an instrument used to measure the humidity in the air, i.e. the amount of vapor in the air, dust and other particles.

A lactometer is a little glass instrument that is used to check for the purity of milk by measuring its density or to find out the content of the water in the milk or to test the richness of the milk. It works on the principle of the specific gravity-the more the amount of water in milk, the more the lactometer will sink in milk. Whereas, the more the milk with cream, the less the lactometer will float.

In standard temperature and pressure, 1 liter of water is equal to 1 kilogram. Similarly, 3 liter of water is equal to 3-kilogram standard weight.