What is Newton’s Second Law of Motion?
The principle of Newton’s second law of motion states that the overall force exerted on an object is equal to the product of its mass and acceleration. In simpler terms, this law describes how the rate of change of momentum of an object is directly proportional to the force applied to it, and it occurs in the same direction as the force.
Momentum = mass x velocity
Thus, change in momentum = (mass x final velocity) – (mass x initial velocity)
Hence, change in momentum = mv – mu
Now we can define Newton’s second law as
F = (mv – mu)/t [where t = time taken]
since acceleration = (final velocity – initial velocity)/time taken
which is a = (v – u)/t
Thus, F = m(v – u)/t which can be rewritten as F = ma
mathematically we can derive it as F = ma
and F = force,
m = mass of the body, and
a = acceleration of the body
Force is measured in Newtons, mass is quantified in kilograms, and acceleration is expressed in meters per second squared.
Examples of Newton’s Second Law of Motion
Below are a few illustrations that exemplify Newton’s second law of motion
1. car on a Highway
Within a moving car, two physical components play significant roles: the force and mass of the car. The force is provided by the car’s engine, propelling it forward, while its mass influences its acceleration. When the car’s mass is substantial, the gravitational force acting on it may diminish the overall acceleration.
As a skydiver descends towards the ground, their body experiences a downward acceleration. This acceleration is directly proportional to the mass of the skydiver. In other words, the mass of the skydiver determines the extent of their acceleration. The skydiver continues to accelerate consistently until they reach a state known as terminal velocity.
In addition, the force responsible for pulling the skydiver towards the ground is identified as the force of gravity. Hence, the force of gravity and the mass of the skydiver are crucial factors in bringing them down to the ground.
3. Hockey Puck
When a hockey puck glides across the ice, it experiences a force of friction that acts to reduce its acceleration. Consequently, the mass of the hockey puck plays a crucial role in determining its acceleration.
The frictional force between the puck and the ice opposes and restricts the puck’s acceleration. However, if a sufficient amount of force is applied to the puck, it will accelerate towards its intended destination. This observation underscores the adherence of a sliding hockey puck to Newton’s second law of motion.
The ability of a rocket to maintain its low weight in space is attributable to the force and mass involved. Upon launch, a rocket accelerates towards its designated destination. The force propelling the rocket is known as thrust, generated by the engine.
Meanwhile, the mass of the rocket is determined by the burnt fuel. As the fuel is consumed, the rocket’s mass decreases, resulting in a lighter-weight for the rocket.
5. Shopping Cart
When you push a cart, you exert a force influenced by the numerous items it contains. Additionally, the shopping cart’s combined mass and contents affect its acceleration. If you purchase more items, the cart’s mass increases, requiring a greater force to accelerate it.
6. A Baseball Hit by a Bat
In this scenario, the force applied by the bat impacts the ball, resulting in its acceleration. The mass of the ball plays a significant role in determining its acceleration. Furthermore, a stronger force applied to the ball leads to greater acceleration.
7. An Aeroplane
Another example of Newton’s second law of motion is evident in the case of an aeroplane. Before takeoff, the aeroplane’s engine generates a force that propels the plane to accelerate along the runway. This acceleration enables the plane to overcome its weight using the lift force.
8. A boat Rowing Through Water
The oars of a boat, as it rows through water, play a crucial role in propelling the boat forward. Consequently, the oars impact the force exerted by the boat. On the other hand, the boat’s acceleration on the water is influenced by the combined mass of the boat itself and its passengers.
9. A Soccer Ball
10. A Basketball
A basketball player utilizes force from their biceps to propel the ball towards the net. During the throw, the ball’s acceleration is directly related to the player’s force and the basketball’s mass.