Table of Contents

## What force is pulling you down to Earth?

Gravity

Gravity is a force, which means that it pulls on things. But the Earth isn’t the only thing which has gravity.

**What is the force between you and the ground?**

Your weight is actually just the force of gravity between your body’s mass and the Earth’s mass. We feel the Earth pulling on us with a force that we call gravity. The ‘force of gravity’ is often expressed in terms of the acceleration the gravitational force will give an object when the object is dropped.

**Are there any forces acting on you when you are not moving?**

An object at rest stays at rest and an object in motion stays in motion at a constant speed and direction unless acted upon by an unbalanced force. In the absence of any forces, no force is required to keep an object moving.

### Why does the Earth pull us down?

Gravity is the reason things with mass or energy are attracted to each other. The reason gravity pulls you toward the ground is that all objects with mass, like our Earth, actually bend and curve the fabric of the universe, called spacetime. That curvature is what you feel as gravity.

**How 9.81 is calculated?**

The acceleration g=F/m1 due to gravity on the Earth can be calculated by substituting the mass and radii of the Earth into the above equation and hence g= 9.81 m s-2.

**What makes a gravitational force noticeable?**

Unless someone is taking very precise measurements in a lab (see for example Cavendish’s famous experiment which determined the gravitational constant, G), the force of gravity must include only really big objects (like the sun, the moon or a planet) to be noticeable.

## What forces act on you when you jump?

Whether you are standing or jumping, the only external forces acting on your body are the normal force from the ground and gravity. How can you jump? Raising your center of mass into the air seems like it would require gravity to diminish or the normal force to grow.

**What are two forces acting on me right now?**

Newton’s Third Law of Motion: The force with which the first body presses the second is called the action force, while the force exerted by the second body on the first one is called the reaction force.

**Why do we not fly off Earth?**

Normally, humans aren’t thrown off the moving Earth because gravity is holding us down. However, because we are rotating with the Earth, a ‘centrifugal force’ pushes us outwards from the centre of the planet. If this centrifugal force were bigger than the force of gravity, then we would be thrown into space.

### What does 9.81 mean?

It has an approximate value of 9.81 m/s2, which means that, ignoring the effects of air resistance, the speed of an object falling freely near the Earth’s surface will increase by about 9.81 metres (32.2 ft) per second every second.

**What is value of G?**

Its value is 9.8 m/s2 on Earth. That is to say, the acceleration of gravity on the surface of the earth at sea level is 9.8 m/s2. When discussing the acceleration of gravity, it was mentioned that the value of g is dependent upon location.

**Which is the strongest force?**

The strong nuclear force

The strong nuclear force, also called the strong nuclear interaction, is the strongest of the four fundamental forces of nature. It’s 6 thousand trillion trillion trillion (that’s 39 zeroes after 6!) times stronger than the force of gravity, according to the HyperPhysics website.

## What is the force that pulls you down?

The amount of force which gravity pulls down an object is called its weight. A force which pulls you down? Is the force that pulls object’s down? What force pulls a bike downhill? The force of Gravity. Gravity is the force that pulls everything down to the ground.

**How does the force of gravity work in the universe?**

After lots of experiments, and some very clever thinking, he worked out that the force of gravity depends on how heavy objects are, and that the pull of gravity between objects gets smaller, the further apart they are. To see how gravity works in our universe, we’re going to take a journey, with a few stops along the way.

**Which is the only force acting on the ball?**

A free body diagram only includes the forces that act on the object, not the forces the object itself exerts on other objects. Neglecting air friction, the only force acting on the ball is gravity. Gravity is acting downward. The ball is at rest. The ground must exert a force equal in magnitude and opposite in direction on the ball.

### How does gravity pull things down to Earth?

Monica Grady receives funding from the STFC, UK Space Agency and the EU. She is a Research Fellow at the Natural History Museum. She is director of her company MGML (UK) Ltd which provides educational resources about space. The Open University provides funding as a founding partner of The Conversation UK. What goes up, must come down. Shutterstock.