Circular motion

what is the relationship between the acceleration due to gravity g and the distance from the centre of the earth

g=GM/R²

why does the value of g vary at different locations onthe surface from the earth

since the earth is not perfectly spherical different locations are at different distances from the earth centre

define angular velocity

the rate of change of angle

define centripetal force

the force required to maintain uniform circular motion; it is directed toward the centre of the circle

define velocity

the rate of change of displacement

state newtons law of universal gravitation

The force of attraction between two point masses is proportional to the product of their masses and inversely proportional to the square of the distance between them

the international space station moves in a circular orbit around the equator at a height of 400km. what type of force is required to keep the ISS in orbit? What is the direction of the force?

gravitational force provides the centripetal force required to keep the satellite in orbit. it is directed towards the centre, towards the earth

an astronaut in the ISS appears weightless. Why?

the astronaut is in a state of free fall along with the space station. this means they are falling at the same rate as the space craft they are in.

After an orbit, the ISS will be above a different point on the earth’s surface. Explain why.

ISS has a different period to that of the Earth’s rotation which means it is not in geostationary orbit

Describe the variation in the weight of the astronauts as they travel from earth to the moon.

Their weight decreases to zero as the astronaut moves away from Earth, and then gains (a lesser than normal) weight as they approaches the Moon.

Why is there no atmosphere on the moon?

The gravitational force on the Moon is too weak to sustain an atmosphere because the Moon does not have enough mass.

If there was no force of friction between the child and a merry-go-round, in what direction would the child move as the merry-go-round starts to rotate?

The child would remain at rest. The merry-go-round would move beneath the child’s feet, but the child would remain stationary.