Question

Which of the following will always be in the direction of net external forceacting on the body?(a) displacement (b) velocity(c) acceleration (d) Change is momentum

Answer 1

answer : option (c) acceleration.

explanation : according to Newton's second law, an object experience a force in the direction of acceleration acting on that object. acceleration of the object is directly proportional to applied force and inversely proportional to mass of that object.

i.e., a ∝ F and a ∝ 1/m

so, a ∝ F/m ⇒a = kF/m

experimentally, k = 1

so, a = F/m

in vector form, a = F/m ......(1)

according to vector concept we know, two vectors A and B will be in same direction when A = p B , where p is constant.

here equation (1) follows the vector concept. hence, acceleration and force are in same direction.

by above explanation, it is clear that acceleration will always be in the direction of net external force acting on the body