question_answer

A mass of 10gm moving horizontally with a velocity of 100 cm/sec, strikes a pendulum bob of mass 10gm. The two masses sticks together. The maximum height reached by the system now is: \[[g=10m/{{s}^{2}}]\]

A) Zero

B)                           5cm    

C) 2.5cm              

D) 1.25cm

Correct Answer: D

Solution :

[d] Apply momentum conservation \[10\times 100=(10+10)V\] V = 50 cm/sec Kinetic energy so acquired is converted into gravitational potential energy \[\frac{1}{2}\times 20{{(50)}^{2}}=20\times 1000\times h\] \[h=1.25cm\]