Question

A hammer weighing 3 kg, moving with a velocity of 10 m/s, strikes against the head of a spike and drives it into a block of wood. If the hammer comes to rest in 0.025 s, the impulse associated with the spike will be :

• A. 30 Ns
• B. -30 Ns
• C. 15 Ns
• D. -15 Ns

Answer 1

The correct option is A 30 Ns

Initial momentum of the hammer $P_i=mu=3\times 10=30kgm/s$

Final momentum of the hammer $P_f=0$

Change in momentum of hammer $\Delta P=P_f-P_i=0-30=-30kgm/s$

Impulse acting on the hammer $I_{hammer}=\Delta P=-30Ns$

Impulse acting on the spike $I_{spike}=-I_{hammer}=30Ns$