A 4.3 g dart is fired into a block of wood with a mass of 22.6 g. The wood block is initially at rest on a 1.4 m tall post. After the collision, the wood block and dart land 3.1 m from the base of the post. Find the initial speed of the dart.

Answer 1

m1 =4.3•10^-3 kg, m2 = 22.6•10^-3 kg, h =1.4 m, L= 3.1 m., v1 =?

m1 •v1 = (m1+m2) •v,
v= m1 •v1 /(m1 + m2) .

h =g•t²/2 => t = sqrt(2•h/g)
L= v•t = v• sqrt(2•h/g),
v =L/sqrt(2•h/g),

m1 •v1 /(m1 + m2) = L/sqrt(2•h/g).

v1= L•(m1 + m2)/m1• sqrt(2•h/g) = …