Correct Option
The correct option is A-4, B-1, C-3, D-2
Explanation
The application of Newton's Laws of Motion and the concept of frictional force in everyday physical phenomena. These laws govern how objects behave when forces act upon them.
Statement-wise Analysis
- A. Dust flying off a beaten carpet (Matches 4 - First Law of Motion/Inertia):
According to Newton's First Law of Motion (Law of Inertia), an object at rest tends to stay at rest unless acted upon by an external force. When a carpet is beaten, the carpet fiber moves suddenly, but the dust particles, due to their inertia of rest, remain in their original position and separate from the carpet.
- B. Recoil of a gun (Matches 1 - Third Law of Motion):
Newton's Third Law states that for every action, there is an equal and opposite reaction. When a gun is fired, the bullet is pushed forward with a specific force (action). Simultaneously, the gun is pushed backward with an equal force (reaction), causing the recoil.
- C. Catching a ball by pulling hands back (Matches 3 - Second Law of Motion/Impulse):
Newton's Second Law relates force to the rate of change of momentum ($F = \frac{\Delta p}{\Delta t}$). By pulling the hands back while catching a fast-moving ball, the cricketer increases the time interval ($\Delta t$) over which the momentum of the ball is reduced to zero. Since force is inversely proportional to time for a constant change in momentum, increasing the time reduces the impact force on the hands, preventing injury.
- D. Bicycle slowing down without pedalling (Matches 2 - Frictional force):
When pedalling stops, the driving force ceases. The bicycle eventually comes to a halt due to external opposing forces, primarily friction between the tires and the road (rolling friction) and air resistance. These forces act in the direction opposite to motion.
Key Takeaway
Newton's Laws Summary: First Law defines Inertia (resistance to change in state); Second Law defines Force as the rate of change of momentum (Impulse concept); Third Law defines Action-Reaction pairs.