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Academic Year 2016- 2017
First Term
Science Revision sheets
PHYSICS
Name: ________________________
Date: _______________
Grade: 9
(A)
Section: _____________
Science Practice :
Q1: Choose the letter of the choice that best answer the questions:
1.
2.
Which of the following units is the SI unit of velocity?
a. meter
c. meter per second
b. metersecond
d. second per meter
In the graph at the right, at what point is
the speed of the ball equal to its speed
at B?
a. A
b. C
c. D
d. E
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3. Acceleration is defined as
a. rate of displacement.
b. the rate of change of displacement.
c. the change in velocity.
d. the rate of change of velocity.
4. Which of the following is the cause of an acceleration?
5.
a. speed
c. force
b. inertia
d. velocity
In the free-body diagram shown to the right, which of
the following is the gravitational force acting on the
car?
a. 5800 N
c. 14 700 N
b. 775 N
d. 13 690 N
6. Newton’s third law of motion involves the interactions of
a. one object and one force.
c.
b. one object and two forces.
7.
d.
two objects and one force.
two objects and two forces
What is the speed of an object at rest?
a. 0.0 m/s
c. 9.8 m/s
b. 1.0 m/s
d. 9.81 m/s
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8. When a car’s velocity is negative and its acceleration is negative, what is
happening to the car’s motion?
a. The car slows down.
b. The car speeds up.
c. The car travels at constant speed.
d. The car remains at rest.
9.
In general, Fnet equals
a. Ff.
c. Fn.
b. Fg.
d. F.
10. The magnitude of the gravitational force acting on an object is
a. frictional force.
c. inertia.
b. weight.
d. mass.
11. What causes a moving object to change direction?
12.
a. acceleration
c. inertia
b. velocity
d. force
In which situation is the net force acting on a car zero?
a. The car increases speed and changes direction.
b. The car increases speed but does not change direction.
c. The car maintains its speed but changes direction.
d. The car maintains both its speed and direction.
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13. In an action-reaction pair, the
a. action force is exerted first.
b. action force and the reaction force are equal in magnitude and act in
the same direction.
c. action force and the reaction force are contact forces only.
d. action force and the reaction force act on two different objects.
14. The average acceleration is the ratio of which of the following quantities?
a. d:v
b. d:t
c. v:v
d. v:t
15. The speed of a car will increase if the car’s
a. initial velocity is positive and its acceleration is zero.
b. initial velocity is positive and its acceleration is positive.
c. initial velocity is positive and its acceleration is negative.
d. initial velocity is negative and its acceleration is positive
16. What are the simplest type of motion?
a. one dimensional motion
b. two dimensional motion
c. three dimensional motion
d. four dimensional motion
17. Displacement to the North or East are ?
a. positive
c.
b. negative
d.
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positive and negative
unspecified
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In the graph below, a toy car rolls from +3 m to +5 m. Which of the
following statements is true?
19.
a.
xf = +3 m
c. xi = +3 m
b.
x = +3 m
d. vavg= 3 m/s
A car goes forward along a level road at constant velocity. The
additional force needed to bring the car into equilibrium is
a.greater than the normal force times the coefficient of static friction.
b.equal to the normal force times the coefficient of static friction.
c.the normal force times the coefficient of kinetic friction.
d.zero.
20.
Which of the following is the tendency of an object to maintain its state
of motion?
a. acceleration
c. force
b. inertia
d. velocity
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II. Fill in the blanks :
[ speed , net force , frame of reference , displacement, second ,
equilibrium , direction , action – reaction pair , zero ,inertia , first ]
Direction
1. Acceleration has both magnitude and ______________
Speed
2. ________________
is the rate of distance with time .
3. When the velocity is constant acceleration is _________________.
Zero
Equilibrium
4. Newton’s First law describes objects in ____________________
,
whether they are at rest or moving with constant velocity
Net force
5. According to Newton’s First Law , the __________________
acting on a
body in equilibrium must be equal to zero.
6. The relationships between mass , acceleration and force are quantified in
newton’s ______________
law .
second
7. When two object interact with one another, the force that the objects exert
Action reaction pair
on each other are called a(n) _________________________ .
8. _________________________________
is a system for specifying a
Frame of reference
precise location of objects in space and time .
Inertia
9. _________________
is the tendency of an object not to accelerate .
Displacement
10. ______________________is
the change in position of an object .
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III. Write whether the statement is ‘ True ’
or ’ False ’.
1. One dimensional motion is the motion of a commuter train on a straight
True
track. _________________
2. In the absence of a net force , a body will preserve its state of
motion. __________
True
False
3. Displacement is distance moved in a specific direction ______________
4. The greater the mass of the body , the greater the body accelerate under
applied force. ___________________
False
5. An object with no net force acting on it is in a state of equilibrium. ________
True
6. F = mc
False
_______________
IV. Match the following :
A
Answer
B
1. Speed
d
a.
South and west
2. Negative displacement
a
b.
Rate of change of velocity
3. Net force
f
c.
Newton’s First Law
4. Acceleration
b
d. distance travelled divided by time interval
5. Inertia
c
e. Change in position of an object
6. Displacement
e
f. product of mass and acceleration
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V. Give reason :
1. Study the picture carefully and answer the questions :
(a)
(a)
What is the net force on the fishing bob in figure (a)
Ans : Zero because the bob is at rest .
(b)
What happens when the bob is acted on by a net force figure (b) ?
Ans : the bob accelerates towards the hooked fish .
(c)
What happens at the instant the fish begins pulling on the rod , the
person reacts by applying a force to the bob ?
Ans : If an equal and opposite force is applied ,the net force remains
zero.
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VI
Answer the following :
1 . Car A travels from New York to Miami at a speed of25m/s . Car B travels
from New York to Chicago , also at a speed of 25m/s. Are the velocities
of the cars equal ? Explain .
Ans : The velocity of Car A does not equal the velocity of Car B even
though their speeds are the same because they are travelling in
different directions.
2. Figure shows the position – time graphs
of the straight line movement of two
brown bears in a wild life preserve.
(a) Which bear has the greater average velocity over the entire period ?
Ans : Bear B
(b) Which bear has the greater velocity at t= 8.0 min ?
Ans : Bear A
(d)
Is the velocity of bear A always positive ?
Ans : No
(e)
Is the velocity of bear B ever negative ?
Ans : No
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3 . What is the difference between the displacement of the photographer
flying from Florida to California and the displacement of the astronauts
flying from California back to Florida ?
Ans : neither ; because the displacements are the same
4. What is the difference between speed and displacement?
Ans : Speed is the rate of distance with time.
Displacement is distance moved in a specific direction.
5. A blowing ball with a negative initial velocity slows down as it rolls down the
lane towards the pins. Is the bowling ball’s acceleration positive or negative
as it rolls towards the pins?
Ans ; positive
6. A coin is tossed vertically upward.
(a) What happens to its velocity while it is in the air ?
Ans : The coin’s velocity decreases , becomes zero at its maximum height
, and then increases in the negative direction until the coin hits the
ground .
(b) Does its acceleration increase, decrease or remains constant while it
is in the air ?
Ans : The coin’s acceleration remains constant .
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7. Can an object be in equilibrium if only one force acts on the object?
Ans : No , either no force or two or more forces are required for
equilibrium .
8. Identify the action – reaction pairs in the following situations :
(a)
A person takes a step
Ans : person pushes on ground ; ground pushes on person
(b)
A snowball hits someone in the back
Ans : snowball exerts force on back ; back exerts force on snowball
9 As the shuttle bus comes to a sudden stop to avoid hitting a dog , it
accelerates uniformly at – 4 .1 m/s2 as it slows from 9.0m/s to 0.0m/s .
Find the time interval of acceleration for the bus .
Ans :
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Bonus questions:
1. A beach ball is left in the bed of a pick up truck . Describe what happens
to the ball when the truck accelerates forward.
Ans : the ball moves towards the back of the truck because inertia keeps
it in place relative to the ground.
2. The force that attracts Earth to an object is equal to and opposite the
force that Earth exerts on the object . Explain why Earth’s acceleration is
not equal to and opposite the object’s acceleration.
Ans : because the Earth has a very large mass.
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