An object of mass 5.0 cg moving with a velocity of 12 ms^ -1 due north hits a stationary body of mass 7.0kg…

Analyze the question: This is a perfectly inelastic collision (the bodies stick together), so we use conservation of linear momentum.

Concept: m₁u₁ + m₂u₂ = (m₁ + m₂)V

Check the units: The question says "5.0 cg" (centigrams), which is almost certainly a typo for 5.0 kg. Taken literally, 5.0 cg = 0.00005 kg, and the final velocity would be about 0.000086 m/s, which matches none of the options. So the intended mass is 5.0 kg.

Solution (using 5.0 kg):

• m₁ = 5.0 kg, u₁ = 12 m/s
• m₂ = 7.0 kg, u₂ = 0 (stationary)

(5.0)(12) + (7.0)(0) = (5.0 + 7.0)V

60 = 12V

V = 5 m/s

Answer: V = 5 m/s due north, which is option D.

Tip: When objects stick together, think "one combined mass": V = (total momentum before) ÷ (total mass). Also, always check the units in the question. Typos like "cg" for "kg" appear in past questions, so pick the interpretation that matches the options.