Projectile Motion and Energy Conservation – Rankers Physics

Potential Energy & Equilibrium: Practice Problem & Solution

Assertion (A): Two balls of different masses are thrown vertically upwards with same speed. They will pass through their point of projection in the downward direction with the same speed in absence of air resistance. Reason (R): In absence of air resistance, the mechanical energy of a projectile is conserved.
Both (A) & (R) are true and the (R) is the correct explanation of the (A)
Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
(A) is true but (R) is false
Both (A) and (R) are false

Solution Explained:

To solve this problem, we apply the core principles of Potential Energy & Equilibrium. Understanding the underlying formula is key to arriving at the correct answer below:

In the absence of air resistance, only gravity acts, a conservative force. Thus, mechanical energy is conserved. This implies that the speed at any height (including projection point) is the same, irrespective of mass.

Both Assertion and Reason are true, and Reason correctly explains Assertion.

Leave a Reply

Your email address will not be published. Required fields are marked *

Similar Practice Questions

Explore conceptually related problems to test your knowledge.

1. An engine pumps water through a hose pipe. Water passes through the pipe and leaves it with a velocity of $2\text{ m/s}$. The mass per length of water in the pipe is $100\text{ kg/m}$. What is the power of the engine? (2010 Pre)
2. Assertion (A): Work done by a force is always same in all inertial frame of references. Reason (R): Work is an invariant physical quantity.  
3. Two springs \(A\) and \(B\) having spring constant \(K_A\) and \(K_B\) (\(K_A = 2K_B\)) are stretched by applying force of equal magnitude. If energy stored in spring \(A\) is \(E\) then energy stored in \(B\) will be: (2001)
4. Assertion (A): If in a round trip work done by a force is zero then force is conservative. Reason (R): Work done by conservative force field is independent of path.  
5. A body of mass 10 kg moves along a smooth inclined plane \( \theta = 30^\circ\) with constant velocity through a distance of 10 m. Calculate the work done by applied external force to move the body through desired distance of 10 m.