ydashti

__** Week 10 (April, 16th, 2012) **__ 01**. A steel ball of mass 0.5 kg is fastened to a cord that is 70 cm long and fixed at the far end. The ball is then released when the cord is horizontal. At the bottom of it's path the ball strikes, a 2.5 kg steel block initially at rest on a frictionless surface. The collision is elastic. Find, a) the speed of the ball b) the speed of the block, both just after the collision

a. In this part, i used this formula, Initial KE + Initial PE = Final KE + Final PE

KE initial = 0, PE final = 0 there will be no mass as they cancel out. Now, we have to solve the equation, V final = sqrt(2*g*h)

b. Conservation of Momentum should be used in this part, P initial = P final

m1V initial1 + m2V initial2 = m1V final1 + m2V final2. V initial2 = 0, V final1=0,

therefore, m1V initial1 = m2V final2

Now we have to solve to fine the speed of the block, solve for V final2

**Very good work Dashti --- Professor**