Gravity of earth value

WHEN YOU JUMP IN THE AIR,you quickly drop back to the ground.And however hard you throw a ball into the air,it always comes down again. The invisible force that pulls everything downwards on Earth is called gravity.But other objects have gravity,too.In fact, every object has gravity– the force called gravitationa attracts, or pulls, other objects. So a ball flying through the air pulls the Earth towards it, as well as the Earth pulling the ball. But because the Earth has so much more mass than the ball, and so a much greater inertia (resistance to being moved), it is the ball that moves. Objects like stars are so massive, they have huge gravitational attraction. The Sun’s gravity holds all the planets, including Earth, in orbit around it.

Earth’s gravity pulls objects down onto its surface. We can measure this force by the amount it stretches the spring in a spring balance. In everyday terms We call it “weight”, and We measure it in kilograms or pounds. But in scientific terms, weight is a force and so it should be measured in units called newtons. Bigger objects with more mass (matter or atoms) are pulled more strongly to the Earth. In other words they weigh more, The Earth and Moon attract each other,but the Earth is much more massive So the Earth stays almost still compared to the moon while the Moon goes around it. The world-famous Leaning Tower of Pisa, in Italy, was slowly being pulled over to one side by gravity. A tall thin object stands upright as long as its top is directly above its base. Then the force of gravity acts straight down through the object. The tower in Pisa was finished in about 350 – but unfortunately, it was built on soft ground. And on one side, the ground was slightly ofter than the other So the tower began to i that side. In recent years, the foundations have been strengthened, and hopefully the Leaning Tower wil not lean any further. Skydivers accelerate towards the ground until the force of gravity pulling them down is balanced by the force of air resistance pushing upwards against them. With these two forces in balance, the skydivers stop accelerating.Their final maximum speed of about 160 kilometres per hour is called their terminal velocity. The Cassini–Huygens spacecraft was launched in 1997 to the giant outer planet Saturn. But even the biggest rocket cannot launch a spacecraft straight to Saturn. So the craft uses the slingshot method (below). The Cassini–Huygens craft was launched not towards Saturn, but at Venus. The gravity of Venus speeds it up until it swings around this planet like a slingshot and heads back to Earth. Earth’s gravity gives it another boost, then it slingshots around the Sun, Venus again, and finally Jupiter, before arriving at Saturn. The Cassini–Huygens probe is due to reach Saturn, with its spectacular rings, in the year 2004. The planet’s gravity will pull the spacecraft faster and faster towards it. But the angle of the craft’s approch should mean that it goes into orbit around saturn.Then it releases is lander probe. This sends radio signals to the orbiter part of the craft, which relays them to Earth.