Moderate -0.8 This is a straightforward conservation of momentum problem with a single collision and coalescence. It requires only direct application of the momentum formula (m₁u₁ + m₂u₂ = (m₁+m₂)v) with careful attention to signs for opposite directions. No problem-solving insight needed beyond standard M1 technique.
2 An ice skater of mass 40 kg is moving in a straight line with speed \(4 \mathrm {~m} \mathrm {~s} ^ { - 1 }\) when she collides with a skater of mass 60 kg moving in the opposite direction along the same straight line with speed \(3 \mathrm {~m} \mathrm {~s} ^ { - 1 }\). After the collision the skaters move together with a common speed in the same straight line. Calculate their common speed, and state their direction of motion.
2 An ice skater of mass 40 kg is moving in a straight line with speed $4 \mathrm {~m} \mathrm {~s} ^ { - 1 }$ when she collides with a skater of mass 60 kg moving in the opposite direction along the same straight line with speed $3 \mathrm {~m} \mathrm {~s} ^ { - 1 }$. After the collision the skaters move together with a common speed in the same straight line. Calculate their common speed, and state their direction of motion.
\hfill \mbox{\textit{OCR M1 2008 Q2 [5]}}