The Hammer and the Feather
On August 2, 1971, on the Moon, astronaut David Scott held out a 1.32 kg hammer and a 0.03 g falcon feather and let go of both at once. They hit the ground together.
Why does that work there and not in a classroom?
Page 1
Science · Physics
Chapter 1: Measurement and Motion in One Dimension
Mass does not appear in the answer.
On August 2, 1971, on the Moon, astronaut David Scott held out a 1.32 kg hammer and a 0.03 g falcon feather and let go of both at once. They hit the ground together.
Why does that work there and not in a classroom?
Make your guess to turn the page.
Still to come: 10 pages · Lab · Words to Know · What We Learned · 4 questions · Explain It in Writing · Open Questions
The idea this lesson is working on — Students believe heavier things fall faster, and everyday life seems to confirm it because of air. The book separates the two causes: the Moon drop removes the air, and the lab model has no mass in it at all. Ask: which forces act, and how does each depend on mass? The idea to reach is that gravity gives every object the same acceleration, and air resistance, a separate force, is what differs.
Air resistance is the everyday complication — Air resistance does not depend on mass, but its effect does: the deceleration it causes is F(air) / m, so light, wide objects are slowed most. The Apollo 15 figures (a 1.32 kg aluminum hammer and a 0.03 g falcon feather) are NASA's. Skydiver terminal velocities vary with body position and altitude; 55 m/s belly-down and about 5 m/s under canopy are typical values. The lab's cart accelerates at 3 m/s², not 9.8, and is presented as a diluted fall.