Question

The diagram shows the pattern of the oil dripping on the road, at a constant rate from a moving car.
Which of the following statements is correct?

(A) The car moves initially with a constant speed and then slows down
(B) The car accelerates initially and then moves with a constant speed
(C) The car starts from rest and keeps accelerating
(D) The car moves with a constant speed all along

Answer 1

Hint We know that in mechanics, acceleration is the rate of change of the velocity of an object with respect to time. Accelerations are vector quantities (in that they have magnitude and direction). The orientation of an object's acceleration is given by the orientation of the net force acting on that object. Again, acceleration is in the same direction as the change in velocity, which is negative here. This acceleration can be called a deceleration because it has a direction opposite to the velocity.

Complete step-by step answer
We know that Newton's second law of motion can be formally stated as follows: The acceleration of an object as produced by a net force is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object.
Initially, the drops are at uniform separation. The rate of dripping being constant, the motion. Then with a constant speed.
Later on, the spacing between the drops keeps decreasing. This means within the same time interval the car covers a lesser distance as the time progresses.
So, later the car slows down.

Hence, the correct answer is Option A.

Note: We know that Newton’s first law states that every object will remain at rest or in uniform motion in a straight line unless compelled to change its state by the action of an external force. This is normally taken as the definition of inertia. In the third law, when two objects interact, they apply forces to each other of equal magnitude and opposite direction.
However, we should know that it is common to use acceleration to mean speeding up and the word deceleration to mean slowing down. Strictly speaking, however, acceleration describes both types of motion. Speeding up might be referred to as positive acceleration and slowing down as negative acceleration.