Verified Solution • 2025–26 Session moderate

QJEEM20Ph7496: JEE Main 2020 Physics - Class 11 JEEM20Ph7496 Solution: A block of mass 1.9 kg is at rest at the edge of a table, of…

A block of mass 1.9 kg is at rest at the edge of a table, of height 1 m. A bullet of mass 0.1 kg collides with the block and sticks to it. If the velocity of the bullet is 20 m/s in the horizontal direction just before the collision then the kinetic energy just before the combined system strikes the floor, is [Take g = 10 m/s2 . Assume there is no rotational motion and loss of energy after the collision is negligable.]

Multiple Choice Options

  • A 23 J
  • B 21 J
  • C 20 J
  • D 19 J

Step-by-Step Verified Solution

JEE Main 2020 (Online) 3rd September Evening Slot Physics - Center of Mass and Collision Question 69 English Explanation

Let velocity of block after collision = v

Using momentum conservation,

pi = pf

0.1×20 = (1.9 + 0.1)V

⇒\Rightarrow 2 = 2 V

⇒\Rightarrow V = 1 m/sec

Kinetic energy just before striking the floor

= 12mv2+mgh{1 \over 2}m{v^2} + mgh

= 12×2(1)2+2×10×1{1 \over 2} \times 2{\left( 1 \right)^2} + 2 \times 10 \times 1

= 21 J

Related Learning Resources & Exam Preparation