Physics Conservation Of Momentum Question. Please Help!?

A 1.0-kg standard cart collides on a low-friction track with cart A. The standard cart has an initial x component of velocity of +0.40 m/s, and cart A is initially at rest. After the collision the x component of velocity of the standard cart is +0.20 m/s and the x component of velocity of cart A is +0.70 m/s .... show more A 1.0-kg standard cart collides on a low-friction track with cart A. The standard cart has an initial x component of velocity of +0.40 m/s, and cart A is initially at rest. After the collision the x component of velocity of the standard cart is +0.20 m/s and the x component of velocity of cart A is +0.70 m/s . After the collision, cart A continues to the end of the track and rebounds with its speed unchanged. Before the carts collide again, you drop a lump of putty onto cart A, where it sticks. After the second collision, the x component of velocity of the standard cart is -0.20 m/s and the x component of velocity of cart A is +0.45 m/s . What is the inertia of the putty?
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