Question

what happens to the carts speed after it hits the box at time 3? *
energy transfers and contact forces in the launcher, cart, box, and track system

it moves backward
it stays the same
it slows down
it speeds up

Explanation:

When the cart hits the box, there is a collision. In a collision, if there is no external force (assuming a simple case like on a friction - less track), the total momentum is conserved. But the cart and the box start moving together. According to the law of conservation of momentum \(m_1v_1=(m_1 + m_2)v_2\) (where \(m_1\) is the mass of the cart, \(v_1\) is the initial velocity of the cart, \(m_2\) is the mass of the box, and \(v_2\) is the velocity of the cart - box system after collision). Since \(m_1 + m_2>m_1\), \(v_2=\frac{m_1}{m_1 + m_2}v_1

Answer:

It slows down