1. Satellites $A$ and $B$ orbit the same planet of mass $M$. Satellite $A$ has a mass of $3m$ and it is located at a height of $R$ from the surface of the planet. Satellite $B$ has a mass of $m$ and it is located at a height of 2$R$ from the surface of the planet.

What is the ratio of the centripetal force acting on $A$ to the centripetal force acting on $B$?

2. A satellite of mass $m$ is in an orbit at a height $h$ from the surface of a planet of mass $M$. The centripetal force acting on the satellite is $F$ and the linear speed is $v$.

What is the new centripetal force and linear orbital speed when it is moved to a new orbit at $2h$ from the surface of the planet?

An alpha particle of mass m and charge $q$, is accelerated through a potential difference $V$ into a magnetic field of flux density $B$ that is at right angles to the direction of motion. Which of the sketches below best describes the relationship between the radius of path $r$ and the potential difference of the accelerating field?

3.

A.			B.
C.			D.

4. A point charge is moved between two parallel plates separated by a distance of $5cm$. The potential difference between the points is $50V$.

What is the average electric field E?

5. A wire is carrying a current $I$ is placed in a region of uniform magnetic field B1​. The magnitude of the magnetic field is $B$, and its direction is into the page. The force acting on the wire is $F$, as shown in the diagram.

The wire, carrying the same current $I$, is now placed with the orientation shown into another region of uniform magnetic field B2​. The magnitude of the magnetic field is $B$, and its direction is out of the page.

What is the correct direction and magnitude of the force acting on the wire in field B2​?

	Direction	Magnitude
A.		$F$
B.		$F$
C.		$F\sin \theta$
D.		$F\sin \theta$

6. A proton and another object with charge +e exert electrical and gravitational forces on one another. To the nearest order of magnitude, what mass must the object have to be so that the net force acting on it is zero?

7. The centers of three masses lie on the same line. The centers of the masses are separated as shown.

The net gravitational force on m2​ is zero when the value of $d$ is one third of $x$. What is the ratio m1/m3​​?

8. A beam of electrons enters a uniform electric field, as shown.

What effect does this field have on the horizontal and vertical components of the electrons' velocity?

9. Which of the following graphs shows the variation of the gravitational field strength of a planet with distance $r$ from the surface of a planet?

A.			B.
C.			D.

10. Planet $X$ has radius $R$ and density $\rho$. The gravitational field strength at the surface of Planet $X$ is $g$.

What is the ratio of the gravitational field strength at the surface of planet Y, which has radius 0.25$R$ and density 3$\rho$, to that at the surface of Planet X?

11. A charge of $X$ and a charge of $20nC$ are held at a fixed distance.

A point where the electric field is zero can only be found in region 1. Which of the following statements is true about the charge on $X$?

12. A conductor carrying electric current out of the plane of the paper is placed between two magnets as shown in the diagram.

At which location is the magnitude of the resultant magnetic field strength largest due to the conductor and the magnets?

13. A positive and a negative charge of equal magnitude are located on the same horizontal line.

What is the direction of the net electric field at the point marked X, equidistant from the two charges?

14. A source of radiation is near a magnetic field that is directed into the page. A sheet of paper is placed in the path of the radiation before it enters the magnetic field.

The gamma radiation is not deflected when entering the magnetic field. Which of the following is correct about the other type of radiation that penetrates the paper sheet and the direction of its deflected path in the magnetic field?

15. A charged particle is moving horizontally when it enters an electric field between two parallel plates. The path followed by the particle when it passes through the plates is shown. Assume gravitational effects to be negligible.

Which statements are correct about the charged particle?

• I. The particle is positively charged.
• II. A magnetic field in a direction into the page could cause the charged particles to move horizontally without deflection.
• III. A magnetic field in a direction out of the page could cause the charged particles to move horizontally without deflection.

16. Two positive charges of magnitude $2C$ and $8C$ respectively are placed 9cm apart. A third charge is introduced between the two charges as shown below;

At what separation, X, from the 2C charge is the electric field strength equal to zero?

17. A satellite $X$ is in a circular orbit of radius $R$ with a period $T$ around Earth.

What will be the orbital radius of satellite Y, travelling in a circular orbit with a period of 8$T$ around Earth?

18. Two objects A and B are separated by a distance $r$. The mass of A is much larger than that of B.

Which of the following is correct about magnitude and direction of the gravitational force exerted by A on B compared to that exerted by B on A?

19. A hydrogen nucleus is held stationary in a uniform vertical electric field, represented by the arrows. Which of the paths shown would require the largest work to be done on the hydrogen nucleus?

20. Two positive charges q1​ and q2​ are separated by a distance $d$. A third positive charge $q$ is placed at a distance d/4 from q1​ so that the charge $q$ is in equilibrium.

What is the ratio q1/q2​​?

21. Planet $A$ has a gravitational field strength $g$ at its surface. Planet $B$ has twice the density and twice the radius of planet $A$.

What is the gravitational field strength at the surface of $B$?

22. Two point charges are separated by a distance $r$ as shown.

23. A satellite is in a circular orbit of radius $R$ around a planet of mass $M$. Which of the following graphs represents the relationship between the centripetal acceleration of the satellite and its orbital radius?

A.				B.
C.				D.

24. Two charges, separated by a large distance, are shown below, along with the electric field lines around each charge.

Which of the following statements is correct?

• I.  The charge $q$ is positive.
• II.  The charge $q$ is equal in magnitude to $+Q$.
• III.  The electric field magnitude near the charge $q$ is greater than the magnitude of the field near the charge $+Q$.

25. An astronaut in a space station orbiting the earth experiences weightlessness.

The following are three statements about the astronaut and the space station:

• I.  The astronaut experiences no gravitational force.
• II.  The centripetal acceleration of the space station is equivalent to the gravitational field strength at that location
• III.  Both the astronaut and the space station have the same acceleration.

Which of these statements is correct?