it is the force that pulls us to the ground.
example: when you throw an apple it falls down because of gravity.
simple, the larger the planet, the greater the force of gravity.
A planets gravity is caused by the distorting effect its mass has on the fabric of spacetime.
There is gravity on all planets. The strength of that gravity varies depending on the size and mass of each planet.
The effect is very small.
answer is mars but all planets have a gravitation effect on the earth even gas planets
Planets can't really get out of their orbits because of gravity; if gravity somehow stopped having an effect, the planets would continue in a straight inertial line with inertia from the point at which gravity stopped.
It keeps them in orbit
Gravity helps to keep the planets in orbit. It also helps to keep the moon's close to the planets.
The motion of the planets are governed by a number of factors: Gravity - The planets are being pulled towards the Sun in free fall. The velocity of the planets - This balances against the force of gravity opposing it and producing on balance the orbit. The mass of the planets. The effect of gravitational attraction between the planet and any satellites it has. The effect of gravitational attraction between the planets and other planets/dwarf planets etc.
First of all, gravity causes the orbital movement in the first place - due to the attraction by the Sun, the planets go around the Sun in ellipses. Because planets also attract each other, the orbits may gradually change over time.
the bigger the planet the more gravity it has because it needs to hold it self together so it has more gravity than smaller planets who require a small amount of gravity to hold themselves toghther
That's "centrifugal force". It's not a "real" force like gravity, but is a convenient way of describing the effect of the inertia of the planets. (The planets would move in straight lines if they were not in a gravity field.)