CHAPTER 7: GRAVITATIONAL FIELDS

Question 1

newton’s law of gravitation

Answer 1

two point masses attract each other with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between them

Question 2

gravitational field

Answer 2

a region of space where a mass experiences a force due to the presence of another mass

Question 3

gravitational field strength

Answer 3

gravitational field strength at a point in a gravitational field is defined as the gravitational force per unit mass acting on a test mass placed at that point

Question 4

gravitational potential

Answer 4

gp at a point in a gravitational field is defined as the work done per unit mass by an external agent in bringing a test mass from infinity to that point (without a change in KE)

Question 5

gravitational potential energy

Answer 5

gpe of a mass at a point in a gravitational field is defined as the work done by an external agent in bringing the mass from infinity to that point (without a change in KE)

Question 6

why is gravitational potential negative

Answer 6

1. gp at infinity is zero
2. gravitational force is attractive in nature
3. direction of external force is opposite to direction of displacement

Question 7

why must the geostationary orbit lie in the plane containing the equator

Answer 7

1. Fg exterted by earth on satellite is towards the center of the Earth
2. circular orbit of the satellite must have a center of orbit coinciding with the center of earth