Question

You Fire A Bullet Into A 3 Kg Wooden Block Attached To A Spring With Spring Constant 70 N/m. When The Bullet Strikes The Block, The Spring Compresses. The Bullet Has A Mass Of 0.03 Kg And Strikes The Block With A Speed Of 200 M/s. What Is The Speed Of The Block And Bullet When They First Start Moving Together?

Answer 1

here at the moment when bullet strikes the block it will have no external force on it

so here we can use momentum conservation

so we will have

`P_i = P_f`

`m_1v_(1i) + m_2v_(2i) = m_1v_(1f) + m_2v_(2f)`

`0.03(200) + 3(0) = 0.03v + 3v`

`6 = 3.03v`

`v = (6)/(3.03)`

`v = 1.98 m/s`

so they move together with speed 1.98 m/s