Question

Assertion :Two balls of different masses are thrown vertically upward with same speed. They will pass through their point of projection in the downward direction with the same speed. Reason: The maximum height and downward velocity attained at the point of projection are independent of the mass of the ball.

• A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
• B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
• C. Assertion is correct but Reason is incorrect
• D. Both Assertion and Reason are incorrect

Answer 1

The correct option is A Both Assertion and Reason are correct and Reason is the correct explanation for Assertion

Maximum height attained $H=\frac{u^2}{g}$ which is independent of mass of ball.

where $u$ is the velocity by which the ball is thrown vertically upward.

Using equation of motion for downward direction, $v^2-0=2gH$

$v^2=2g\frac{u^2}{2g}$ $⟹v=u$ (downward)

Velocity of the object thrown vertically upward is equal (but in opposite direction) at the two points which lie on same horizontal level.

Thus the two balls which are thrown upward with the same speed will have same speed at the point which passes through the point of projection in downward direction.

Hence the Assertion and the Reason are correct and the reason is the correct explanation for Assertion.