Question

Two water balloons of mass 0.35 kg collide and bounce off of each other
without breaking. Before the collision, one water balloon moved at a velocity
of 2.5 m/s east, while the other moved at a velocity of 2.25 m/s west. After
the collision, one balloon moves at a velocity of 1.75 m/s west. What is the
velocity of the other water balloon?
O
A. 2 m/s west
O
B. 0.25 m/s east
O
C. 0.25 m/s west
O
D. 2 m/s east

Answer 1

Answer:

Option D

2 m/s East

Explanation:

From the law of conservation of momentum, the sum of initial momentum equals the sum of final momentum

Momentum, p=mv where m is the mass and v is the velocity

Since the masses are the same then

$m(u_1+u_2)=m(v_1+v_2)$  

Therefore

$u_1+u_2=v_1+v_2$

where $v_1$ and $v_2$ are final velocities of objects while $u_1$ and $u_2$ are the initial velocities respectively

Taking East direction as positive then West as negative and by substitution

$2.5+-2.25=v_1-1.75$

Therefore

$v_1=2 m/s$ hence East since it's positive