Question

The collision between a hammer and a nail can be considered to be approximately elastic.

Part A

Calculate the kinetic energy acquired by a 12-g nail when it is struck by a 600-g hammer moving with an initial speed of 5.0 m/s .

Express your answer using two significant figures.

K =

  J  

Answer 1

In an elastic collision, the final speed of the initially stationary object is given by:

v = 2mV/(m+M)

m is initially stationary mass =12g
M is initially moving mass =600
V is intial velocity of moving mass (can be "+" or "-") = 5 m/s

This equation comes from solving 2 equations: a conservation of kinetic energy equation, and a conservation of linear momentum equation.

Substitute values to find v and hence the KE

v = 2mV/(m+M)

v= 2*12*500cm /612

v= 19.60 cm/s

v= 0.196 m/s

K.E = 0.5* 0.012*0.196*0.196

K.E = 0.000230