Looking for NCERT Solutions? Check out here.
Force: Pushing and pulling of an object is called force. There are two types of force.
Balanced force: When equal forces act on an object from opposite direction it is called balance force. In this case, no motion is happen.
Unbalanced force: When unequal forces act on an object from opposite direction it is called unbalanced force. In this case, motion is happened to be in the direction of greater force.
There are three laws of motions:
The Newton’s first law of motion states that an object stays at rest or in motion until an external force acts on it.
The Newton’s second law of motion states that external force can make changes in the direction of a moving object.
Momentum: It is the product of an objects mass and its velocity. It is denoted with p. The SI unit of momentum is kg m/s2.
The Newton’s third law of motion states that every action has an equal and opposite reaction.
The property that resists any changes in the state of motion of an object is called Inertia. Example: If an object is at rest, it tends to stay at rest and if an object is in motion, it tends to remain in motion.
The Inertia of an object is directly proportional to its mass. It means that higher mass equal higher Inertia and vice-versa.
Suppose an object has mass m and it is moving with initial velocity u along a straight line. It was uniformly accelerated to velocity v in time t with constant force F.
So, it’s initial momentum will be p1 = mu
And it’s final momentum will be p2 = mv
The change is momentum is ∝ p2 – p1
∝ mv – mu
∝ m × (v – u).
The rate of change of momentum ∝ m x (v - u) / t
Or, the applied force, F ∝ m x (v - u) / t
F = km x (v - u) / t
F = kma
The conservation of momentum states that if two object collide each other their total momentum remains unchanged.
The formula for conservation of momentum is
m1u1 + m2u2 = m1v1 + m2v2
Here, m1 is the mass of the first object
m2 is the mass of the second object.
u1 is the initial velocity of the first object.
u2 is the initial velocity of the second object.
v1 is the final velocity of the first object.
v2 is the final velocity of the second object.