Practice Test 9

On an icy (nearly frictionless) straight road, Car A (mass $m_A = 1000\ \text{kg}$) travels east at $v_{A i} = +12\ \text{m/s}$ and rear-ends Car B (mass $m_B = 1000\ \text{kg}$) traveling east at $v_{B i} = +6\ \text{m/s}$. They lock together in a perfectly inelastic collision. Taking east as positive, what is the common final velocity $v_f$ (in m/s)?

A head-on elastic collision occurs between two carts on a low-friction track. Cart A has mass $m_A = 1.0\ \text{kg}$ with initial velocity $v_{A i} = +4.0\ \text{m/s}$ (right). Cart B has mass $m_B = 1.0\ \text{kg}$ with initial velocity $v_{B i} = -2.0\ \text{m/s}$ (left). After the collision, Cart B is observed moving right at $v_{B f} = +4.0\ \text{m/s}$. Using conservation of momentum only, what must Cart A’s final velocity $v_{A f}$ be (in m/s) for momentum to be conserved?