Newton's Second Law

The Newton's second law gives us the key to mathematical problem solving, establishing the relationship between forces and acceleration (and therefore velocity). The Newton's 3 laws are fundamental to understanding and being able to solve any mechanical or dynamic problem. The Newton's first law and the Newton's third law are the most intuitive.

Index

FORMULA FOR NEWTON'S SECOND LAW

The formula for Newton's second law is: F=m*a

Force equals mass multiplied by acceleration. This means that:

  • Knowing the mass of an object, and knowing the forces acting on it, you can get the acceleration. From the acceleration, and knowing the direction of the forces, you can know the velocity, the trajectory...
  • Knowing the acceleration and mass, derive the forces acting on the body.

FORCES THAT CAN ACT ON AN OBJECT

Forces acting on an object can be of many types, mechanical, pneumatic, and above all in any direction. We would have to go into vectorial terrain to be able to define forces properly. However, there are some "basic" forces that we see more commonly, and we are going to look at some examples.

WEIGHT FORCE

There is a force that is always acting on the Earth, which is the force of gravity. weight. This weight is a force in a direction perpendicular to the ground on which we stand.

Segunda Ley de Newton Peso

If we have a floor underneath, a force will appear in the opposite direction and in the same direction (Newton's third law), and because we are in equilibrium we do not move.

FRICTIONAL FORCE

The frictional force is another very important force that is present in all moving bodies. Whether on the ground, in the air or in water, there is always going to be a frictional force which opposes the movement. Depending on the surface concerned, it will have a coefficient of friction or other.

Segunda Ley de Newton Rozamiento

The frictional force is in the opposite direction to the motion and is what causes a body in motion on Earth to always end up stopping, if the force is not applied. In space, since there is no air, the force of friction is zero, hence the rotational speeds that spacecraft reach, with hardly any force applied.

In the case of the ground, it is the frictional force that causes a BALL TURN. If there were no friction, or very little friction, as in the case of ice, the ball would not turn and hence the wheels would slip on the ice.

FORCE EXERTED ON A BODY

Any force that is exerted on a body, whether it be pushing, with a machine, or with a pole, will generate a force. This force can either encounter an opposition and an opposing force (wall, floor,...) or generate an acceleration, according to Newton's second law.

ACCELERATION

Acceleration is the increase in speed in a unit of time. We all know what acceleration is intuitively, for example in the case of a car. There is an acceleration always acting on the Earth, which would be the gravity. Gravity at the Earth's surface is 9.8m/s2. That is why our weight (force) is equal to mass by the gravity. As we go up in height (into space) the acceleration of gravity decreases and so the force of the weight decreases as we go into space. Here you can see different values of the gravity.

NEWTON'S SECOND LAW EXPERIMENTS

In this experiment, with a set of pulleys, we can learn about force distributions and Newton's laws, applying them to how pulleys work and how they work correctly to reduce weight.
In this simple but fun experiment we are going to make a homemade rocket. The rocket will be propelled with citric acid and bicarbonate, and when it comes into contact with water, it will shoot up.

NEWTON'S LAWS

See the Newton's laws:

en_GBEnglish
es_ESSpanish en_GBEnglish