Orbital motion

satellite

• something that orbits something else

• less massive objects move around more massive objects due to a force of gravity

What keeps satellites in a circular orbit?

gravity provides the force

natural satellites

• moon

• earth

• halley’s comet (orbits sun)

• titan (saturn’s largest moon)

artificial satellites

• ISS

• Hubble space telescope

• Naustar I

• Sputnik I

What is the difference between a planet and a natural satellite?

A planet orbits a star, while a natural satellite orbits a planet

What is a similarity between planets and natural satellites?

They both orbit objects in space and do not emit their own light

What is the difference between natural and artificial satellites?

Natural satellites form naturally, while artificial satellites are man-made and placed into orbit

What is a similarity between natural and artificial satellites?

A: They both orbit objects in space

What force keeps an object in orbit?

Gravity provides the centripetal force that keeps an object moving in a circle

What is centripetal force?

A force that acts towards the centre of a circular path

Why does an object in circular orbit accelerate even if its speed stays constant?

Because its direction is constantly changing, so its velocity changes

What happens to speed in a non-circular (elliptical) orbit?

Speed changes—an object speeds up when closer and slows down when further away

if a car is on a semi circular bend what forces provide the centripetal force

friction between tyres and the road

(2)

the tension is a force along the string

so it always points to the centre of the circle when the conker is swung

as it is being swung in the air in a circular motion (3)

• the conkers velocity changes direction as it moves in a circular path

• the change of velocity is towards the centre of the circle

• so the conker is continuously accelerating towards the centre of the circle