Answer :
Use the principle of conservation of momentum ... momentum after the collision is equal to the momentum before it.
Momentum = (mass) x (speed).
Momentum before the collision:
Big blob . . . (15) x (3) = 45 kg-m/s
Little blob . . (12.5) x (0) = zero.
Total . . . . . . 45 kg-m/s
Momentum after they meet and stick:
Combined blob . . . (15+12.5) x (speed)
Momentum after = momentum before:
(27.5) x speed = 45 kg-m/s
Divide each side by 27.5 :
Speed = 45 / 27.5 = 1.636 m/s (rounded)
Momentum = (mass) x (speed).
Momentum before the collision:
Big blob . . . (15) x (3) = 45 kg-m/s
Little blob . . (12.5) x (0) = zero.
Total . . . . . . 45 kg-m/s
Momentum after they meet and stick:
Combined blob . . . (15+12.5) x (speed)
Momentum after = momentum before:
(27.5) x speed = 45 kg-m/s
Divide each side by 27.5 :
Speed = 45 / 27.5 = 1.636 m/s (rounded)