Block 1, of mass m1 = 7.90 kg , moves along a frictionless air track with speed
ID: 1480671 • Letter: B
Question
Block 1, of mass m1 = 7.90 kg , moves along a frictionless air track with speed v1 = 25.0 m/s . It collides with block 2, of mass m2 = 23.0 kg , which was initially at rest. The blocks stick together after the collision. (Figure 1)
Part A Find the magnitude pi of the total initial momentum of the two-block system. Express your answer numerically. pi = kg?m/s
Part Part B Find vf, the magnitude of the final velocity of the two-block system. Express your answer numerically. vf = m/s
Part C What is the change ?K=Kfinal?Kinitial in the two-block system's kinetic energy due to the collision?
Explanation / Answer
by using mument conversion
m1v1+m2v2=(m1+m2)Vf
7.90X25=30.9Vf
Vf=6.391m/s
initial energy of system is =kinetic energy of m1+kinetic energy of m2
initial energy=2468.75
initial energy = final energy
=final energy-initial energy
=631.0534-2468.75
=1837.69 loss