Question

Consider a ball at rest in the middle of a toy wagon. When the wagon is pulled forward the ball
(A) Rolls Forward
(B) Stays Stationary
(C) Rolls Sidewards
(D) Rolls Backwards

Answer 1

Hint: Understand the given scenario. A ball is at rest in the middle of the wagon and the force is applied to it. Understand Newton's laws of motion with the concept of inertia and relate to which law the given scenario applies to.

Complete answer:
In order to understand what exactly happens, let us first get to know of the term called inertia. Inertia can be called as a resistance of any object to change is speed or acceleration or direction of motion etc. This makes the object move in the straight line along the direction of force. So, if force is applied forward, it moves forward and backward, it moves backward etc.
Now, let us use the concept of inertia on our scenario. The ball is at rest, so is the wagon. When a force is applied on the wagon, the wagon tends to move along the direction of the force. If the wagon consists of a rock of mass m, and if the force applied on the wagon is lesser than that of mass of the rock, it stays idle on the wagon , despite applying force.
So since the mass of the ball is lesser than that of the force applied to pull a wagon, the ball immediately moves backward on the initial stages of force application due to law of inertia, to oppose the direction of motion. As the wagon is pulled further, Newton's first law comes into picture, as the object will stay at rest unless the extra forward pull is given to it.
So the ball starts to move forward. Due to the law of inertia acting before it is in state of rest, it moves backward first.

Hence, option (D) is the correct answer.

Note: Newton’s first law states that the object remains in state of rest or motion, unless and until an external force acts upon it to change its state. The above-mentioned case is a classic example of how the body reacts to newton’s first law of motion.