Gravity basics
Why does the Moon not fall onto Earth if gravity attracts it?
Acceleration due to gravity
Does g = 9.8 m/s² everywhere on Earth?
Weightlessness in orbit
Why do astronauts feel weightless inside the ISS?
Tides
How does the Moon cause ocean tides?
Falling objects
If we drop a hammer and a feather on the Moon, which lands first?
Escape velocity
What speed must a rocket reach to leave Earth’s gravity?
Artificial gravity
Can we create gravity in a spaceship?
Satellites
Why don’t satellites fall back to Earth?
Weight vs mass confusion
If you take a 5 kg brick to the Moon, what happens to its weight and mass?
Black holes
Why is gravity so strong inside a black hole?
Sound propagation
Why can’t sound travel through space?
Speed of sound
Why does sound travel faster in water than in air?
Echo formation
Why don’t we hear echoes in small rooms?
Ultrasound use
How does ultrasound help doctors look inside the human body?
SONAR
How do submarines “see” underwater?
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