Transcript Answer - Issaquah Connect

Semester 1 Final Exam Review
Covering: Topic 1; Mechanics;
Take out: your notes, your book (if
you brought it), a whiteboard
Instructions
• You will work together as a team within your
seating group
• It will not be necessary to answer in the form
of a question…
• It WILL be necessary to show complete work,
or draw diagrams, or do something else to
visually represent your answer on your
whiteboard
• Raise your hand when you’re done and your
answer will be checked and appropriate scores
awarded.
Semester Finals Jeopardy
Physics
What goes up
Phundamentals
must come
down
Get a move
on!
May the
Impulses,
Force be with Crashes, and
you
Coasters
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10
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50
As of Jan. 16, 2012, there were
approximately 312,859,385 people
living in the United States.
Report this number in terms of its
Order of Magnitude
Answer
Log (312859385)  8.495  8
OM  10 people
8
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List 5 of the 7 fundamental metric units
Answer
Fundamental Metric Units
Length: Meter
Time: Second
Mass: Kilogram
Amount of material: Mole
Electric Current: Ampere
Light intensity: Candela
Temperature: Kelvin
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37.5 m·s-1 is equivalent to
how many km·h-1?
Answer
 37.5m  1km  3600s 
1
km



  135 h  135km  h
 s  1000m  1h 
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A motorcycle accelerates at a rate of
17.5 km·h-2. What is its acceleration in m·s-2?
Answer
 17.5km  1h  1h  1000m 
2

0
.
00135
m

s





2
 h
 3600s  3600s  1km 
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A mass is measured to be m=4.4±0.2 kg, and
is moving with a speed v=18±2 m·s-1. find
the absolute uncertainty in the kinetic energy
of the mass.
Answer
2 2
K  mv   (4.4kg)(18m  s )  712.8 J  710 J
1
2
2
1
2
0.2
% mass 
100  4.5%
4.4
2
% velocity  100  11.1%
18
% energy  4.5  11.1  11.1  26.7%
AbsUnc.  (0.267)  (712.8 J )  190  200 J
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 KE  700  200J
Including both direction and units, what is
the average acceleration due to the
gravitational field of Earth
Answer
-2
m·s towards
9.81
the
center of the Earth
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What is the force of gravity that causes a
75.0 kg mass to accelerate (assume that
air resistance is negligible)
Answer
2
Fg  m  g  (75.0kg)  (9.81m  s )  736 N
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A basketball is thrown upwards with an
initial velocity of 8.75 m·s-1. To what
maximum height will it reach?
Answer
Known :
v0  8.75m  s
1
v0
a  9.81m  s
d ?
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v  v0  2ad
2
0  (8.75)  2(9.81)( d )
19.62d  76.56
2
2
2
2
d  3.90m
Describe 2 factors that will increase
the effect of air resistance acting on a
falling body.
Answer
1. Increased surface area
2. Decreased mass
3. Increased velocity
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A ball is tossed up into the air from a point
2.50 m above the ground with a velocity of
3.68 m·s-1. How much time will it take for
the ball to reach the ground?
Answer
known :
v0  3.68m  s 1
v?
a  9.81m  s
d  2.50m
t ?
v  v0  2ad
2
2
2
v  3.68  (2)( 9.81)( 2.50)
2
2
v  (62.59)  7.91m  s 1 (down)
v  7.91m  s
1
v  v0  at
 7.91  3.68  (9.81)t
 11.59  9.81t
t  1.18s
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This is a two part question:
-How can the average velocity of a
moving object be determined from a
displacement-time graph?
-How can the displacement of a moving
object be determined from a velocity-time
graph?
Answer
The SLOPE of the displacement-time
graph is equal to the velocity
The AREA UNDER THE LINE of a
velocity time graph is equal to the
displacement
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A long-boarder has a constant
acceleration of 1.5 m·s-2. How long will
it take for his velocity to change from
5.0 m·s-1 to 11.0 m·s-1?
Answer
known :
v0  5.0m  s
v  11m  s
1
a  1.5m  s
t ?
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1
2
v  v0  at
11.0  5.0  (1.5)t
6.0
 t  4.0s
1.5
A plane flies 3000.0 km
in 5.000 hours. What is
its average velocity in
meters per second?
Answer
d 3000.0km 1000m 1h
v 


t
5.000h
1km 3600 s
1
v  166.7m  s
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This is a two part question:
A runner runs 2 complete 400. m laps
on a track in 2.5 min.
-What is her average speed (in m/s)?
-What is her average velocity (in m/s)?
Answer
d 2  400.m 1 min
1
s 

 5.3m  s
t
2.5 min
60s
d
0m
1
v 
 0m  s
t 2.5 min
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A hiker walks 1.5 km NE, then turns and
walks 2.5 km due north before hiking 6.0 km
in a direction 30.0° SW. What is the hiker’s
overall displacement from his starting point?
Answer
x1  1.5 cos(45 )  1.06km
y1  1.5 sin( 45 )  1.06km
x2  0km
y2  2.5km
x  1.1  0  5.2  4.1km
y  1.1  2.5  3.0  0.6km
x3  6.0 cos(30.0 )  5.2km
y3  6.0 sin( 30.0 )  3.0km
d  x2  y2
d  (4.1) 2  (0.6) 2
d  4.1km
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 y
1  0.6 

tan    tan 
  8.3 NW
x
 4.1 
1
In your own words, what are
Newton’s three laws of motion?
Answer
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A 55.0 kg box is pushed across the floor
with a force of 450. N. If there is a
frictional force equal to 275 N, with what
acceleration will the box move?
Answer
Fnet  ma
(450  275)  (55.0)a
175
2
 a  3.18m  s
55.0
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A 25.0 kg sign is hung from the ceiling
with two cables that each make an angle
of 42.0° with the horizontal ceiling.
What is the tension in each of the wires?
Answer
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Give two specific examples of a contact
force and two specific examples of a field
force (“at-a-distance” force)
Answer
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A car with an initial velocity of 25.0 m·s-1
comes to a stop in 45.0 m. What is the
magnitude of the braking force acting on
the car?
Answer
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What does the area under a Force vs. Time
graph represent?
Describe what kind of information this
value can give us.
Answer
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A soccer ball (m = 0.430 kg), initially at
rest, is kicked and reaches a velocity of
25.0 m/s. If the time that the player’s foot
is in contact with the ball is 0.685 s, what
average force is exerted by the foot?
Answer
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A car, m1 = 1250 kg, is initally at rest. If it is
struck from behind by a larger car, m2=1550
kg, which is traveling at 15.0 m/s.
If the two cars stick together after impact:
a) What type of collision is this?
b) What is the final velocity of the cars after
the collision?
Answer
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A large safe (m = 725 kg) is lifted to a
height of 4.75 m. When it reaches that
height, the rope holding it snaps, and the
safe falls to the floor.
a) How much kinetic energy will it have
when it reaches the floor?
b) What is the safe’s speed the instant
before crashing into the floor?
Answer
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A ball of clay, m=0.250 kg, is initially at
rest when it is struck by an identical ball of
clay that is traveling at a speed of 6.50 m/s.
How much kinetic energy is lost during the
collision if both clay balls stick together
upon impact?
Answer
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