हवा के माध्यम से गति करने वाली वस्तुओं पर हवा द्वारा कौन सा बल लगाया जाता है, जो उनकी गति का विरोध करता है?

Match List-I (Phenomenon) with List-II (Explanation): List-I (a) Contact Force (b) Non-contact Force (c) Frictional Force (d) Pressure List-II 1. Force exerted when two surfaces are in direct contact 2. Force exerted without physical contact 3. Force opposing relative motion between surfaces 4. Thrust acting per unit surface area Select the correct answer code:

According to Newton's second law of motion, if the acceleration of a body is halved while its mass remains constant, the net force acting on it will _________.