Question

When a running horse suddenly stops, the rider falls___________.
A. forwards
B. backwards
C. to his right
D. to the horse’s right

Answer 1

Hint: You may compare this situation with any of your daily life experience. Say, you were traveling in a bus, and the driver applies a sudden brake, in which direction would you fall? Also, recall the concept of inertia that is the property of the body to resist change in its state of rest or uniform motion in the absence of an external force and hence, answer the question.

Complete answer:
In the question we are given a rider on a running horse. If this running horse were to stop suddenly, we are asked to find the direction in which the rider falls. So which direction do you think the rider falls? Will he fall forward or backward or to his right or to the right of the horse?
If you had any prior experience riding a horse, you may be able to answer this directly. If not, let us think of a similar case that we may have faced in our daily life. If you were traveling in a car or bus or any other vehicle, if the driver were to apply the brake suddenly, in which direction would you fall? You may recall that you had fallen forward. So, let us see why this happens.
In order to explain the reason behind this, we will have to introduce the term ‘inertia’.
Newton’s first law of motion, if you may recall, states that ‘Every body continues to be in its state of rest or of uniform motion in a straight line unless compelled by some external force.’ This particular property of the body is what we call ‘inertia’. The word ‘inertia’ means ‘resistance to change’.
Rider on the horse is in motion along with the horse and when the horse makes an abrupt halt, due to inertia of the rider, he continues to be in state of motion in the forward direction and hence falls forward.

So, the correct answer is “Option A”.

Note:
You should note that state of rest or uniform motion directly implies zero acceleration. So, Newton’s first law of motion can be otherwise expressed as, ‘If the net external force on a body is zero, its acceleration is zero. Acceleration can only be non-zero, if there exists net external force acting on the body.’