Question

These questions consist of two statement, each printed as assertion and reason. While answering these question you are required to choose any one of the following five responses.

Assertion : If a body is thrown upwards. the distance covered by it in the last second of upward motion is about 5 m irrespective of its initial speed .

Reason : The distance coveted in the last second of upward motion is equal to that covered in the first second of downward motion when the particle is dropped.

• A. If both assertion and reason are true but the reason is the correct explanation of assertion
• B. If both assertion and reason are true but the reason is not the correct explanation of assertion
• C. If assertion is true but reason is false.
• D. If both the assertion and reason are false
• E. If reason is true but assertion is false.

Answer 1

The correct option is A If both assertion and reason are true but the reason is the correct explanation of assertion

After the last second, body attains the maximum height and thus its velocity at that instant is zero. As the physical scenario must be same, so if we drop a body then it must travel the same distance in first second as that covered in the last second of upward motion.

For downward motion : $u=0$ $a=g=10m/s^2$

Using $S_t=ut+\frac{1}{2}a{t}^2$ where $t=1$ s

$\therefore$ $S_1=0+\frac{10\times 1^2}{2}=5$ m

Hence both the assertion and reason are true and the reason explains the assertion very well.