Physics 9702/42 — February/March 2017

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

questions

100

marks

120

minutes

Topics Magnetic Fields · Gravitational Fields · Quantum Physics · Thermodynamics · Ideal Gases · Oscillations · +7 more

Q1Gravitational FieldsFree sample

(a)

Define gravitational potential at a point.

(b)

A rocket is launched from the surface of a planet and moves along a radial path, as shown in Fig. 1.1.

Fig. 1.1

The planet may be considered to be an isolated sphere of radius $R$ with all of its mass $M$ concentrated at its centre. Point A is a distance $R$ from the surface of the planet. Point B is a distance $4R$ from the surface.

(i)

Show that the difference in gravitational potential $\Delta\phi$ between points A and B is given by the expression

\Delta\phi = \frac{3GM}{10R}

where $G$ is the gravitational constant.

(ii)

The rocket motor is switched off at point A. During the journey from A to B, the rocket has a constant mass of $4.7 \times 10^4\ \text{kg}$ and its kinetic energy changes from $1.70\ \text{TJ}$ to $0.88\ \text{TJ}$ .

For the planet, the product $GM$ is $4.0 \times 10^{14}\ \text{N m}^2\ \text{kg}^{-1}$ . It may be assumed that resistive forces to the motion of the rocket are negligible.

Use the expression in (b)(i) to determine the distance from A to B.

distance = ______ $\text{m}$

The rest of this paper

11 more questions

Q2Thermodynamics · Ideal Gases10M
Q3Oscillations · Magnetic Fields12M
Q4Medical Physics4M
Q5Communication8M
Q6Electric Fields · Gravitational Fields9M
Q7Electronics10M
Q8Magnetic Fields · Motion in a Circle9M
Q9Alternating Currents · Magnetic Fields11M
Q10Quantum Physics8M
Q11Quantum Physics5M
Q12Nuclear Physics8M

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