Topic 9 Motion in Fields Multiple Choice Questions. Answer on the Question Sheet
5.
1.
The gravitational potential at the surface of Earth
is V. The radius of Mercury is about one third the
radius of Earth. Earth and Mercury are spheres of
the same density and the volume of a sphere is 4/3
π r3 The gravitational potential at the surface of
Mercury is
A.
2.
B. 1/3V
C.
3V
D.
y
4 kJ
B.
10 kJ
C.
16 kJ
.D.
9V
x
–Q
+Q
At which position, or positions, is the electric potential
due to the four point charges equal to zero?
A.
At the centre of the square only.
B.
Along the x-axis only.
C.
Along the y-axis only.
D.
Along the x-axis and the y-axis.
40 kJ
The diagram below shows some lines of
equipotential in the region of an electric field.
6.
X
–Q
+Q
The gravitational potential at point X due to the
Earth is –7 kJ kg-1 At point Y, the gravitational
potential is – 3 kJ kg-1 The change in
gravitational potential energy of a mass of 4 kg
when it is moved from point X to point Y is
A.
3.
1/9V
Four point charges of equal magnitude Q are placed at the
corners of a square as shown below. The centre of the
square is at the origin of the x-axis and the y-axis.
A ball rolls off a horizontal table with velocity v. It
lands on the ground a time T later at a distance D from
the foot of the table as shown in the diagram below.
Air resistance is negligible.
Y
v
table
Which graph best shows the magnitude E of the
electric field strength along the line XY?
A.
D
B.
E
E
A second heavier ball rolls off the table with velocity v.
Which one of the following is correct for the heavier ball?
X
Y
position
X
Y
position
D.
C.
E
A
B
C
D
Time to land
T
T
Less than T
Less than T
Distance from table
D
Less than D
D
Less than D
E
7.
X
Y
position
X
Which one of the following statements about
electric potential gradient is correct?
A. Electric potential gradient is numerically equal to
the gradient of the electric field.
B. Electric potential gradient at a point is numerically
equal to the electric field strength at that point.
C. When one joule of work is done in moving one
coulomb of charge between two points, the electric
potential gradient between the points is one volt
per metre.
D. When one joule of work is done in moving one
coulomb of charge to a point, the electric potential
gradient at that point is one volt per metre.
A satellite is in orbit about Earth. The satellite moves to
an orbit closer to Earth. Which of the following correctly
gives the change in the potential energy and the kinetic
energy of the satellite?
Change in potential
energy
Decreases
Decreases
Increases
Increases
Y
position
A
B
C
D
4.
8.
Change in kinetic
energy
Increases
Decreases
Increases
Decreases
Which of the following expressions correctly relates
the radius R of the circular orbit of a planet round a
star to the period T of the orbit?
A.
3
2
R ∞T
B.
C.
R2 ∞ T3
D.
1
2
∞T
3
R
1
∞ T3
2
R
1
Topic 9 Motion in Fields Multiple Choice Questions. Answer on the Question Sheet
14.
9.
A.
10.
A satellite of mass m and speed v orbits the Earth
at a distance r from the centre of the Earth. The
gravitational field strength due to the Earth at the
satellite is equal to
v
r
mv
v2
. C.
.
r
r
D.
mv 2
.
r
A
B
An isolated point has mass M. A second small
point object of mass m is placed a distance x from
the larger mass. Which one of the following is a
correct expression for the gravitational potential
energy of the mass m?
A.
C.
11.
.B.
GM
x
GM
 2
x

GMm
x
GMm
 2
x
C
D

B.
D.
Planet X has radius R and mass M. Planet Y has
radius 2R and mass 8M. Which one of the
following is the correct value of the ratio
15.
The rings of Saturn are rocks that orbit the planet. The
period T of each particle depends on its distance r
from the centre. The period T is proportional to rn
Which one of the following is n equal to?
A.
1.0
B.
1.5 C. 2.0
D.
3.0
16.
Select the true statement concerning the vertical
component of the velocity and the acceleration of a
projectile when it is at its maximum height? (The
acceleration of free fall is g.)
gravitatio nal field strength at surface of planet X
?
gravitatio nal field strength at surface of planet Y
A.
12.
The diagram shows lines of electric equipotential. The
change in potential on moving from one line to the next
is always the same. At which point does the electric
field strength have its greatest magnitude?
4
B.
2
C.
1
2
D.
1
4
The diagram below shows the path of a projectile
in the absence of air resistance.
Vertical
position
A
B
C
D
17.
A.
Horizontal position
B.
Which of the diagrams represents the path of the
projectile under the same conditions when the air
resistance is considered? (The path in absence of air
resistance is shown as a dotted line.)
C.
D.
18.
A. Vertical
position
B. Vertical
position
Vertical Component
maximum
maximum
zero
zero
Acceleration
zero
g
zero
g
Which one of the following statements correctly
defines the gravitational potential at a point P in
a gravitational field? The work done:
per unit mass in moving a small mass from
point P to infinity.
per unit mass in moving a small mass from
infinity to point P.
in moving a small mass from infinity to point P.
in moving a small mass from point P to infinity.
The diagram shows two lines of equipotential. Line
X has a potential of +50 V and line Y has a potential of
+100V. The distance between X and Y is 2.0 cm.
X
Horizontal position
C. Vertical
position
Horizontal position
Y
+50 V
+100 V
D. Vertical
position
2.0 cm
Horizontal position
Horizontal position
13. Which correctly describes the nature of
electric potential and electric field strength?
A
B
C
D
Potential
Scalar
Scalar
Vector
Vector
Which one of the following correctly gives the
direction of the electric field and its strength?
Field Strength
Scalar
Vector
Scalar
Vector
A
B
C
D
Direction
X→Y
X→Y
Y→X
Y→ X
Strength Vcm-1
25
100
25
100
2
Topic 9 Motion in Fields Multiple Choice Questions. Answer on the Question Sheet
3