Newton's Laws of Motion Newton's First Law: Law of Inertia An object at rest remains at rest, and an object in motion continues to move at a constant velocity,...
An object at rest remains at rest, and an object in motion continues to move at a constant velocity, unless acted upon by an external unbalanced force. This law describes the concept of inertia.
The acceleration a of an object is directly proportional to the net force F acting on it and inversely proportional to its mass m. Mathematically, F = ma.
Problem: A 2 kg object experiences a net force of 10 N. Calculate its acceleration.
Solution:
For every action force, there is an equal and opposite reaction force. These forces act on different objects and are examples of action-reaction pairs.
The momentum of an object is the product of its mass and velocity: p = mv. Momentum is a vector quantity.
The impulse acting on an object is the product of the net force and the time over which it acts: Impulse = F Ć t. Impulse is equal to the change in momentum.
Principle of Conservation of Momentum: In a closed system, the total momentum before a collision equals the total momentum after the collision.
Collisions can be elastic (kinetic energy is conserved) or inelastic (kinetic energy is not conserved). Explosions are examples of inelastic collisions where objects gain kinetic energy.
An 800 kg car traveling at 20 m/s collides with a 1200 kg truck at rest. If the vehicles stick together after impact, calculate their final velocity.
Solution:
Understanding Newton's laws and principles of momentum is crucial for analyzing motion, forces, and collisions in A Level Physics.