Question

Two rams run toward each other. One ram has a mass of 49 kg and runs west
with a speed of 7 m/s, while the other has a mass of 52 kg and runs east with
a speed of 9 m/s. What will the momentum of the system made up of the two
rams be after they collide? Assume the total momentum of the system is
conserved
A. 811 kg-m/s west
B. 811 kg-m/s east
C. 125 kg-m/s west
O D. 125 kg-m/s east
S

Answer 1

Answer: (d)

Explanation:

Given

Mass of the first ram $m_1=49\ kg$

The velocity of this ram is $v_1=-7\ m/s$

Mass of the second ram $m_2=52\ kg$

The velocity of this ram $v_2=9\ m/s$

They combined after the collision

Conserving the momentum

$\Rightarrow m_1v_1+m_2v_2=(m_1+m_2)v\\\Rightarrow 49\times (-7)+52\times (9)=(52+49)v\\\Rightarrow v=\dfrac{125}{101}\ m/s \quad[\text{east}]$

Momentum after the collision will be

$\Rightarrow 101\times \dfrac{125}{101}=125\ kg-m/s\ \text{East}$

Therefore, option (d) is correct