Easy -1.2 This is a straightforward application of conservation of momentum with a single unknown. Students simply need to write m₁u₁ + m₂u₂ = (m₁ + m₂)v, substitute the given values, and solve a linear equation for the mass of B. It requires only direct recall of a standard formula with no problem-solving insight or multi-step reasoning.
2 Two toy trains, \(A\) and \(B\), are moving in the same direction on a straight horizontal track when they collide. As they collide, the speed of \(A\) is \(4 \mathrm {~m} \mathrm {~s} ^ { - 1 }\) and the speed of \(B\) is \(3 \mathrm {~m} \mathrm {~s} ^ { - 1 }\). Immediately after the collision, they move together with a speed of \(3.8 \mathrm {~m} \mathrm {~s} ^ { - 1 }\).
The mass of \(A\) is 2 kg . Find the mass of \(B\).
2 Two toy trains, $A$ and $B$, are moving in the same direction on a straight horizontal track when they collide. As they collide, the speed of $A$ is $4 \mathrm {~m} \mathrm {~s} ^ { - 1 }$ and the speed of $B$ is $3 \mathrm {~m} \mathrm {~s} ^ { - 1 }$. Immediately after the collision, they move together with a speed of $3.8 \mathrm {~m} \mathrm {~s} ^ { - 1 }$.
The mass of $A$ is 2 kg . Find the mass of $B$.
\hfill \mbox{\textit{AQA M1 2012 Q2 [3]}}