JEE Exam » JEE Study Material » Physics » Newton’s second law of motion

Newton’s second law of motion

Newton's second law of motion defines that an object's acceleration is determined by two factors: the net force acting on the body and the object's mass. The acceleration is proportionate to the net power.

Newton’s first law of motion outlines how objects behave when all external forces are equal and balanced. For instance, the first law of motion, commonly referred to as inertia, stipulates that if all forces acting on a body cancel each other, the object’s acceleration will be zero. When items are in equilibrium, they cannot accelerate (the state in which all forces balance). Newton stated that an object would accelerate only if subjected to a net or unbalanced force operating on it. Due to the presence of an imbalanced force, an object accelerates, modifying both its speed and direction or altering both simultaneously.

Newton’s second law of motion:

Newton’s second law of motion describes how objects behave when the forces acting on them are out of balance. Newton’s second law of motion defines that an object’s acceleration is determined by two factors: the net force acting on the body and the object’s mass. Acceleration is proportional to the net force applied to the object.

Newton’s second law quantifies the consequences of a force on a moving body. In simple terms, it states that the rate at which a body’s momentum changes is proportional to the direction and magnitude of the force acting on it. A body’s momentum is equal to the product of its mass and velocity. Momentum is a quantifiable vector quantity with a magnitude and direction, like velocity. An object’s momentum can change when a force is applied to it. Newton’s second law is widely considered one of the most fundamental laws in all physics. For an object with a constant mass m, it is possible to formulate the equation F = ma, where F = force and a = acceleration are vector values. When an object is subjected to a net force, it will accelerate following the equation if the force is positive. No net forces act on a body that does not accelerate, and the reverse is true.

Derivation Of Newton’s Second Law:

Newton’s second law of motion: Equation

There are two ways to express Newton’s second law of motion:

As the size of the net force increases, the acceleration of an object produced by this net force rises as well, and this acceleration is inversely proportional to the object’s mass.

The following equation expresses this verbal statement:

a = Fnet/m

Often, the above equation is rearranged into a more known form, as seen below. The mass multiplied by the acceleration equals the net force.

Fnet= ma

The net force has been the focus of this entire conversation. This is because acceleration can be directly correlated to the net force exerted.

Changing Mass

If a car is at a zero-point position at time zero, we have reached the zero-point location t0. The vehicle has zero mass and moves at the same speed in other ways. A force F causes the car to travel to point 1, specified by the location x1 and the time t1 at which it occurred. During the journey, the car’s mass and velocity change to m1 and v1. If we know the value of the operating force, we may use Newton’s second law to derive the values of m1 and v1.

The force acting on the vehicle can be expressed as the following equation when the difference between points 1 and 0 is taken into account:

Consider that the mass is constant. This is a valid assumption for an automobile because the only change in mass between points 1 and 0 would be the fuel burned. If we consider modest changes in time, the fuel’s weight is likely insignificant compared to the rest of the vehicle. However, a bottle rocket’s mass changes as it travels; thus, we can only look at its momentum shifts while discussing it.

Difference form : F = (m1v1-m0v0)/((t1-t0)

Constant mass

Newton’s second law can be equivalent as follows for a constant mass:

We already know that acceleration is a ratio of velocity change to time change.

After that, the Newton’s second law of motion takes on a familiar form:

With constant mass: F =m( v1-v0)/(t1-t0)=ma

According to the equation above, a body will move if it is exposed to an external force. Therefore, an object’s mass and acceleration are inversely related to each other.

An example of Newton’s second law:

The motion of a rocket as it travels through space is governed by all three of Newton’s laws of motion. If the missile needs to slow down, accelerate, or change direction, a force is applied to push it in the desired direction. The engine usually generates this force. The amount of pressure used and the position at which it is applied can cause changes in either or both the speed (the magnitude component of acceleration) and direction of the object being pushed.

Now that we understand how a large body in an inertial reference frame acts when subjected to an external force, such as how the engines generate the push maneuver of the rocket, we can consider what happens to the body that is exerting the external pressure itself. Newton’s Third Law of Motion describes the circumstance in which we find ourselves.

Applications:

  • Kicking a ball involves applying force in only one direction. In other words, the more pressure we exert on the ball, the further it will move
  • Empty shopping carts are far easier to maneuver through supermarket aisles than filled ones, and accelerating heavier loads is more complicated
  • When two people are walking, the person who weighs more will move slower because the lighter person’s speed will accelerate more quickly

Conclusion:

According to Newton’s second law of motion, the acceleration of an item is influenced by two factors: the net force exerted on the object and the object’s mass. It is inversely proportional to the mass of a body’s net force, and its acceleration is directly proportional to that force’s magnitude. Acceleration of the body is less if the mass is more. Scalar quantities such as mass are related to the matter. When a system consists of multiple objects, the overall mass is essential.

Acceleration is caused by force, which is an interaction. A force, in general, is an interaction that results in a change in the environment. An interaction’s force is a vector quantity that its magnitude can quantify. When a system is subjected to many external forces, the net external force matters. When combining forces, utilize geometry rather than arithmetic because force is a vector quantity. A force must originate outside an object to accelerate it.