Which way is down? Falling balls and planets
Answers are for parents and teachers.
1
Hang a small heavy object on a string and watch it. Draw it and an arrow showing where “down” is.
The string hangs straight down; the arrow points down toward the Earth.
2
Find the average of 12 cm, 15 cm and 18 cm.
(12 + 15 + 18) ÷ 3 = 45 ÷ 3 = 15 cm.
3
Explain, using the words air resistance, why a parachute slows a falling person.
A parachute is wide, so air resistance pushes up on it strongly and slows the fall.
4
Earth’s year is about 365 days. Mercury is nearer the Sun and its year is about 88 days. How many 88-day years fit in 352 days?
352 ÷ 88 = 4 Mercury years.
5
Write a claim, evidence and reasoning to answer: how does gravity affect the way objects move?
Claim: gravity pulls objects toward the centre of Earth and holds planets in orbit. Evidence: balls fall and the Moon stays in orbit. Reasoning: mass pulls on mass, and the pull gets weaker with distance.