Gravity is a force of attraction that acts between bodies that have a mass.
Gravity was discovered by Sir Isaac Newton.
Gravity acts on all objects the same. If you drop a bowling ball and a tennis ball at the same time, they will both hit the ground at the same time because gravity is a constant.
The more matter something has the more gravitational pull it has. Our moon is much smaller than Earth and only has about 1/6 the amount of gravity .
Jupiterâ€™s gravity is about 2.5 times stronger than Earthâ€™s because of its size. That is why people weigh different weights on different planets.
Speed is the measure of how far you move in a given time. To find speed you need to know time and distance.
If you rolled a ball down a hill that was 100 meters long and it took 20 seconds to reach the bottom, its speed is 5 m/s. So the equation for velocity equals, v=d/t or distance over time.
The speed of the ball throughout the trip changed. It started off slow and got faster as it rolled down.
So, this calculation gives you an average speed and describes the movement for the entire trip down the street.
Before we talk about the laws, we have to learn about force, which is a push or a pull. Gravity is a force, as well as friction. Everytime you turn a page or open a door, you are using force to do so.
Law #1: Inertia- An object at rest tends to stay at rest, and a moving object moves in a straight line until it is acted upon by an outside force.
In other words, things donâ€™t stop or start by themselves. The reasons things stop is because of friction.
Law #2: Acceleration depends on the mass of an object and the force pushing or pulling the object.
Force = mass x acceleration, F=mXa
Acceleration = force/mass, a=F/m
It takes less force to accelerate something with a small mass. This is why large trucks need more powerful motors to get them going from a complete stop. If you want to go faster, you have to use more force. Like having to pedal harder on a bike.