Physics 9702/42 — October/November 2015

Cambridge A-Level · A Level Structured Questions · worked solutions for every part, with the mark scheme

questions

100

marks

120

minutes

Topics Ideal Gases · Gravitational Fields · Temperature · Electric Fields · Communication · Motion in a Circle · +7 more

Q1Gravitational FieldsMotion in a CircleFree sample

A satellite of mass $m_S$ is in a circular orbit of radius $x$ about the Earth.

The Earth may be considered to be an isolated uniform sphere with its mass $M$ concentrated at its centre.

(a)

(i)

Show that the kinetic energy $E_K$ of the satellite is given by the expression

E_K = \frac{GMm_S}{2x}

where $G$ is the gravitational constant. Explain your working.

(ii)

State an expression, in terms of $G$ , $M$ , $m_S$ and $x$ , for the potential energy $E_P$ of the satellite.

(iii)

Using answers from (i) and (ii), derive an expression for the total energy $E_T$ of the satellite.

$E_T$ = ______

(b)

Small resistive forces acting on the satellite cause the radius of its circular orbit to change.

Use your answers in (a) to state, for the satellite, whether each of the following quantities increases, decreases or remains constant.

(i)

total energy

(ii)

radius of orbit

(iii)

potential energy

(iv)

kinetic energy

The rest of this paper

11 more questions

Loading the full paper…