Year 9 Physics Quiz
Object in our Solar System
Earth
Moon
Gravitational field strength on the
surface in N·kg-1
9.8
1.6
The gravitational field strength for a planet (or satellite – like the Moon)
indicates the force on a 1 kg mass on the planet or moon’s surface. The force
that holds you on the Earth – on the seat you are sitting on now – is known as
your weight.
15.The gravitational field of the Moon is weaker than that of the Earth. What
will be the weight of a 50kg mass on the Moon? Show your work.
d. 50 N
b. 50 kg
c. 490 N
a. 80 N
Show your Work:
F = M ⨯ A;
;
Fweight = 50 kg ⨯ 1.6 N·kg-1 = 80 N
Year 9 Physics Quiz
16.Match the Units with its measurement: a mass, b force, and c
acceleration?
a. Mass
Meters per second per second (m·s-2)
b. Force
Kilograms (kg)
c. Acceleration
Newtons (N)
17.Why is it sensible on diagrams to represent a force by an arrow?
a. Because Force is a vector quantity
b. Because Force is a scalar quantity
c. Because Force has direction as well as magnitude
d. Both A and C
18.Why should mass not be represented by an arrow?
a. Because Mass is a vector quantity
b. Because Mass is a scalar quantity
c. Because Mass is communicates the magnitude of matter
d. Both B and C
19.Which will produce a bigger acceleration:
a. A force of 10N acting on a mass of 5kg.
b. Or a force of 5N acting on a mass of 10 kg.
Show your work:
F=MxA
a. 10 N = 5 kg x A; A = 10/5 N·kg-1; A = 2 N·kg-1
b. 5 N = 10 kg x A; A = 5/10 N·kg-1; A = 0.5·N kg-1
A force of 10N acting on a mass of 5 kg is going to produce a faster
acceleration by a factor of 4.
20.An astronaut is weighed before he sets off to the moon. He has a mass of
80 kg. What will his weight be on earth?
a. 80 kg
b. 80 N
c. 784 kg
Show your work: F = M ⨯ A;
Fweight = 80 kg ⨯ 9.8 N·kg-1 = 784 N
d. 784 N
;
When he arrives on the Moon, will his mass be more, less or the same?
Explain: His mass will be the same because the mass of an object remains the
same, no matter what the gravitational field force.
Year 9 Physics Quiz
Will his weight be more, less, or the same? Explain
Explain: His weight will be less because it is a function of the gravitational force
acting on his mass. The gravitational force of the moon is less than that of
earth, therefore his weight will also be less.
21.The figure below shows the forces acting on a lorry as it travels along a
flat road
5000 N
B
A
D
1300 N
C
1200 N
5000 N
Two of these forces have effects that cancel each other out. Which
two? Explain your answer.
a. A-B
b. A-C
c. B-C
d. B-D
Explain: B and D gave equal force vectors but in opposite directions. The
resultant or “net” force between B and D will be 0, as the forces will be
“cancelling” or balancing each other.
What is the resultant force acting on the lorry? Give its magnitude
and direction. Show your work.
a. 125,000 N Left
b. 100 N Left
c. 100 N Right
d. 5000 N Down
Show work: B – D = 5000N – 5000N = 0 N + A – C = 1300 N – 1200 N = 100 N
What effect will this resultant force have on the speed at which the
lorry is travelling?
Explain: The unbalanced force to the left will steadily increase the speed
(accelerate) the lorry to the left.
22.What force is needed to give a mass of 20kg an acceleration of 5 m·s-2 ?
Show your work.
a. 20 N
b. 5 kg
Show work: F = M x A = 20 kg x 5 m·s-2 = 100 N
c. 100 N
d. 9.8 m·s-2
Year 9 Physics Quiz
23.A train of mass 800,000 kg is slowing down. What acceleration is
produced if the braking force is 1,400,000 N? Show your work.
a. 800 Mg
c. 1.4 m·s-2
b. 8.0 N
d. 1.75 m·s-2
Show work: A = F / M = 1,400,000 N / 800,000 kg = 1.75 m·s-2
24.A car speeds up from 12 m·s-1 to 20 m·s-1 in 6.4s. If its mass is 1200kg,
what force must its engine provide? Show your work.
c. 12 kg
a. 1,500 N
d. 6,400 m·s-2
b. 1,200 N
Show work: A = ΔV/ΔT = (20 – 12) m·s-1 / 6.4 s = 1.25 m·s-2
F = M x A = 1200 kg x 1.25 m·s-2 = 1,500 N
25.What is the weight of a 65 kg person on Earth? Show your work.
d. 65 N
a. 65 kg
c. 637 kg
b. 637 N
Show work:
= 65 kg x 9.8 N·kg-1 = 637 N
26.What is the weight of a 65 kg person on the moon? Show your work.
d. 637 kg
a. 65 kg
c. 65 N
b. 104 N
Show work:
= 65 kg x 1.6 N·kg-1 = 104 N
27.What is the unbalanced force acting on a rocket if its
weight is 25,000 N and the thrust of its engines is
35,000 N? Show your work
35,000 N – 25,000 N = 10,000 N
a. 5kN
b. 10kN
c. 1 N
d. 35 kN
28.The cyclist and a bicycle have a combined mass of 80kg
and accelerate forward at 0.9 m·s-2. Calculate the size of
the unbalanced force (net force) producing this
acceleration. Show your work.
F = M x A = 80 kg x 0.9 m·s-2 = 72 N
a.
80 N
b. 12 N
c.
72 N
d. 80 kg
Year 9 Physics Quiz
29.Two forces act on a parachutist during a drop. One force is the weight W
(490N) of the parachutist. The other force is the upwards pull P (400N)
from the parachute harness on the parachutist. The parachutist has a
mass of 50kg. What is the acceleration of the parachutist? Show Work
a. 9.8 m·s-2
b. 8 m·s-2
c. 50 m·s-2
d. 1.8 m·s-2
A = Fnet/ M = (490 – 400) N/ 50 kg
= 90 N/ 50 kg = 1.8 m·s-2
30.A shopping trolley and its contents have
a mass of 20kg. The trolley is pushed
with a force P. The friction force
(backward force) acting on the trolley is
20N. The acceleration of the trolley is 0.5 m·s-2 in the forward direction.
What is the size of the unbalanced force acting on the trolley? Show your
work.
Fnet = M x A = 20 kg x 0.5 m·S-2
= 10 N is the net
force in the left direction
31.In Question 30, What is the size of P? Show your work.
FP = Fnet + FBalanced = 10 N + 20 N = 30 N
Year 9 Physics Quiz
32.Bonus: We discussed an example of inertia in class that produced some
interesting results. Discuss the experiment and the results giving as
much detailed explanation as you can.
The key is the acceleration.
The balloon is lighter than
air, and, because of inertia,
when the van starts to
accelerate the bulk mass of
air moves to the perceived
back of the van. It takes a
unbalanced force to
accelerate the air, pushing
it forward. Since the
balloon is lighter than air,
the balloon gets pushed
forward by the air collecting
at the back of the van.
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