state newton second law of motion and give two examples
Answers
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Newton's second Law of Motion.
Newton's second law of motion states that the rate of change of momentum of a body is directly proportional to the force applied, and this change in momentum takes place in the direction of the applied force.
Expression for Newton's second Law of Motion.
Consider a body of mass ‘m’ moving with velocity v.
The linear momentum of a body is given by:
p = mv
Now According to Newton’s 2nd Law of Motion:,
Force is directly proportional to rate of change of momentum, that is
F ∝ dp/dt
F = k dp/dt,
where k is the constant of proportionality and its value is 1.
F = 1 * d(mv)/dt
F = md(v)/dt
F = ma
Examples of Newton's second Law of Motion.
- Example 1:
While catching a cricket ball, the player keeps his hands backwards in order not to get hurt. In doing so, he increases the time taken by the ball to reach his hands which reduces the ball's velocity to zero and the player is not hurt.
- Example 2:
In a high jump event, the players are made to fall on cushioned bed or sand so that they don't get hurt. This increases the time taken by them to fall on the ground and hence their velocity is reduced to zero and they don't get hurt.
Hope it helps !!
Explanation:
Defining Newton’s Second Law of Motion
Newton’s second law states that the acceleration of an object depends upon two variables – the net force acting on the object and the mass of the object. The acceleration of the body is directly proportional to the net force acting on the body and inversely proportional to the mass of the body. This means that as the force acting upon an object is increased, the acceleration of the object is increased. Likewise, as the mass of an object is increased, the acceleration of the object is decreased.
Acceleration is directly proportional to the net force and inversely proportional to the mass.
Newton’s second law can be formally stated as
The acceleration of an object as produced by a net force is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object.
This statement is expressed in equation form as,
a=Fnetm
The above equation can be rearranged to a familiar form as
F=ma
Since force is a vector, Newton’s second law can be written as
F⃗ =ma⃗
The equation shows that the direction of the total acceleration vector points in the same direction as the net force vector.
Deriving Newton’s Second Law
Force is equal to the rate of change of momentum
For Changing Mass
Let us assume that we have a car at a point (0) defined by location X0 and time t0. The car has a mass m0 and travels with a velocity v0. After being subjected to a force F, the car moves to point 1 which is defined by location X1 and time t1. The mass and velocity of the car change during the travel to values m1 and v1. Newton’s second law helps us determine the new values of m1 and v1 if we know the value of the acting force.
Taking the difference between point 1 and point 0, we get an equation for the force acting on the car as follows:
F=m1v1−m0v0t1−t0
Let us assume the mass to be constant. This assumption is good for a car because the only change in mass would be the fuel burned between point “1” and point “0”. The weight of the fuel is probably small relative to the weight of the rest of the car, especially if we only look at small changes in time. Meanwhile, if we were discussing the flight of a bottle rocket, then the mass does not remain constant and we can only look at changes in momentum.
For Constant Mass
For a constant mass, Newton’s second law can be equated as follows:
F=mv1−v0t1−t0
We know that acceleration is defined as the change in velocity divided by the change in time.
The second law then reduces to a more familiar form as follows:
F=ma
The above equation tells us that an object will accelerate if it is subjected to an external force and the amount of force is directly proportional to the acceleration and inversely proportional to the mass of the object.
List some examples of Newtons second law of motion
We all know that the great scientist has made a major contribution to the world of Physics. The laws given by Newton are totally a great foundation and many concepts lay on these laws.
Newton’s Second Law
The newtons second law is mainly based on the two terms of physics that is force and acceleration.
Newtons second law can be formally stated as
The acceleration of an object as produced by a net force is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object. The acceleration of the body that is acting is directly proportional to force and is inversely proportional to the mass of the body. Hence when the force acting on a body is increased, the acceleration increases. Similarly, when the mass of the body is increased, the acceleration decreases.
Following are some examples of Newton’s Second Law of motion:
- If you use the same force to push a truck and a car, the car will have more acceleration than the truck because the car has less mass.
- It is easier to push an empty shopping cart than a full one, because the full shopping cart has more mass than the empty one. This means that more force is required to push the shopping cart.
- When a person kicks a ball the person exerts force in a specific direction, that is the direction in which it will travel. In addition to this, the stronger the ball is kicked, the stronger the force we put on it and the further away it will travel.
- Suppose two people are walking and among the two people, if one is heavier than the other, then the one weighing heavier will walk slower because the acceleration of the person weighing lighter is greater