The first law states an object in motion tends to stay in motion unless acted on by an external force. The second law says the force of an object on another object is determined by its mass times its acceleration. The third law of motion says for every action there is an equal and opposite reaction.
The first law of motion says an object in motion will stay in motion until something stops it. It's important to understand that energy can neither be created nor destroyed. When something loses energy, the energy isn't gone; it is simply transferred to another object or another state.
For example, the batter hits the ball into center field and the center fielder catches it. The baseball is given energy by the bat coming into contact with the ball. It will continue moving until something stops it, in this case the center fielder. The ball's energy is then transferred to the glove.
The second law of motion explains how the force of one object on another object is found by multiplying the mass (in grams) by the acceleration (in meters per second). Force is measured in newtons.
Returning to the baseball example, when the bat makes contact with the ball, the bat is exerting force on the ball. To determine the amount of that force, we multiply the mass of the bat, by the speed of the bat as it hits the ball. The weight of the bat is 822 g. When the bat hits the ball, the bat is traveling at about 20 meters per second. So, by multiplying 822 g by 20 meters per second, we can determine that the bat exerts 16,440 newtons (N) of force on the baseball. That, along with other factors like ball weight and size, help determine how far the baseball will go.
The third law of motion says that for every action there is an equal and opposite reaction.
For example, at the moment the bat comes in contact with the ball, the energy in the bat is transferred to the ball. The ball gains the energy, while the bat loses the energy.
These laws are put into use every day. A forensic scientist would use the laws of motion to gather evidence at an accident scene. A rocket scientist uses these laws to figure out how much thrust is necessary to send a space shuttle into orbit. You might not even realize it, but you use the laws to some extent when you open a jar of peanut butter.