Question

Physical independence of force is a consequence of:
(a) Third law of motion
(b) Second law of motion
(c) First law of motion
(d) All of these laws

Answer 1

Hint: If motion of body in vertical direction does not affect the motion of body in horizontal direction then this phenomenon is called physical independence of force. Now, using these principles, we consider all the laws of motion and apply this principle in it and based on that we will find the answer.

Complete step-by-step answer:
 In question we are asked which law states that force is independent of physical contact. Now, we will consider all the options one by one.
Considering option (a) third law of motion can be given as “For every action in nature there is an equal and opposite reaction.” So, from this it can be said that we will apply force to move any object than only the object will move which is the reaction of that force. Hence, it can be said that motion of the body is dependent on force applied as per the third law of motion.
Considering option (b) second law of motion can be given as” Force applied to any object is equal to the product of mass of that object and its acceleration in the direction of force applied.” So, from this it can be said that here also force is an important factor as per second law of motion.
Considering option (c) first law of motion can be given as “Everybody will continue its motion or remain in steady state until and unless any external force is applied to it.” From this it can be said that as per first law of motion, any motion of an object is physically independent of force.
Thus, option (c) is the correct answer.

Note:As per the principle, physical independence of force means the vertical component should not affect the motion on horizontal component and in second as well as in third law Force depends on acceleration and acceleration is a two-dimensional quantity, hence, we can say that only first law of motion is our correct answer. So, in this way also we can find our answer.