Transcript Semester 1 Final Jeopardy Review

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0 10 20 30 40 50 60
Velocity (m/s)
The graph below is a velocity vs time
1-25
graph. What is the distance covered in
the first 10 seconds?
0
2
4
6
8
10 12 14 16 18 20
Time (s)
0 10 20 30 40 50 60
Velocity (m/s)
0
1-25A
2
4
6
8
10
12
Time (s)
Calculate the area under the graph for
the first 10 seconds.
Area = 310 m/s*s or
310 m
14 16
18
20
What is the acceleration of a car
that goes from 0 to 100 m/sec in 2
minutes? (answer in m/sec2)
2-20A
What is the acceleration
of a car
that goes from 0 to 100 m/sec in 2
minutes? (answer in m/sec2)
a = v / t and,
t = 2 min (60sec/min) = 120 sec
so…
a = (100m/s - 0m/s)/120 sec
a = 0.833 m/sec2
A dragster accelerates
down the
1-15
track at a constant rate. It starts
from rest and crosses the finish
line moving at a speed of 250 mph.
What is its average velocity?
A dragster accelerates
down the
3-5A
track at a constant rate. It starts
from rest and crosses the finish
line moving at a speed of 250 mph.
What is its average velocity?
vavg = (vi + vf)/2
vavg = (250mph + 0mph)/2
vavg = 125 mph
How far would1-20
a sprinter run if
3-25
they start at rest and end the race
moving at a velocity of 20 m/sec?
Assume they run for 10 seconds.
How far would
a sprinter run if
3-25A
they start at rest and end the race
moving at a velocity of 20 m/sec?
Assume they run for 10 seconds.
vavg = (vi + vf)/2
vavg = (20m/sec + 0m/sec)/2 = 10 m/sec
d = vavgt = (10m/sec)(10sec)
d = 100 meters
How much time
would it take to
3-20
run 100 meters if you start at
10m/s and accelerate at 2 m/sec2?
How much time
would it take to
3-20A
run 100 meters if you start at
10m/s and accelerate at 2 m/sec2?
d = vit + 1/2at2
100m = 10m/s*t + 0.5*2m/s2*t2
Use quadratic formula
t = 6.18 seconds
You and a friend
2-20 push a heavy
crate across the floor at a constant
speed. If you push with a combined
force of 100 N, how hard is friction
pushing back on the crate?
A)
B)
C)
D)
less than 100 N
100 N exactly
more than 100 N
not enough info
You and a friend
2-20A push a heavy
crate across the floor at a constant
speed. If you push with a combined
force of 100 N, how hard is friction
pushing back on the crate?
A)
B)
C)
Ff = 100D)
N
less than 100 N
100 N exactly
more than 100 N
not enough info
Fpull = 100 N
3-10A
What is the weight
of a 50-kg
object as it falls at a speed of 100
m/sec in a vacuum chamber?
3-10A
What is the weight
of a 50-kg
object as it falls at a speed of 100
m/sec in a vacuum chamber?
The speed of the object has no
effect on its weight, so…
m/sec2)
W = mg = (50 kg)(9.8
W = 490 Newtons
Fg
A 2000-kg car accelerates
down the road.
3-20A
The friction from the road drives it with a force of
5000 N, and air drag is 1400 N.
What is the car’s acceleration?
A 2000-kg car accelerates
down the road.
3-20A
The friction from the road drives it with a force of
5000 N, and air drag is 1400 N.
What is the car’s acceleration?
Fnet = ma
and
Ff
Fnet = 5000 N – 1400 N
So… Fnet = 3600 N = (2000 kg)a
a = 3600 N/2000 kg = 1.8 m/sec2
Ff
A 75-kg parachutist 3-25A
is falling through the air –
while experiencing an air drag of 200 N. If they
fall from rest for 10 seconds in this manner, how
fast are they moving?
A 75-kg parachutist 3-25A
is falling through the air –
while experiencing an air drag of 200 N. If they
fall from rest for 10 seconds in this manner, how
fast are they moving?
F
f
vf = at so we must find a…
Fnet = Weight – Drag = ma
(75 kg)(9.8 m/s2) – 200 N = (75 kg)a
535 N/75 kg = 7.13 m/s2 = a
vf = at = (7.13 m/s2)(10 sec) = 71.3 m/s
Fg
In space, a rocket of 2-25
mass 250-kg is pushed
by a thrust force of 10,000-N through 12
kilometers. How fast is it moving when the
engine shuts off?
In space, a rocket of2-25A
mass 250-kg is pushed
by a thrust force of 10,000-N through 12
kilometers. How fast is it moving when the
engine shuts off?
F = ma
10,000N = 250kg * a
a = 40m/s2
vf2 = vi2 + 2ad
vf2 = 02 + 2*40m/s2*12,000m
vf = 980 m/sec
1-15A
3-5
What is the gravitational force
between two planetoids if each has a
mass of 500,000,000kg and their
centers of mass are 200km apart?
1-15A
What is the gravitational force
between two planetoids if each has a
mass of 500,000,000kg and their
centers of mass are 200km apart?
F = Gm1m2 / r2
F = 6.67x10-11*500,000,0002 / 200,0002
F = 4.17x10-4 N
4-20A
3-10
2-15
If a 0.5 kg ball spins on a table at
12m/s, attached to a 1m string, what is
the tension on the string?
4-20A
2-15
If a 0.5 kg ball spins on a table at
12m/s, attached to a 1m string, what is
the tension on the string?
F = mv2 / r
2
F = 0.5*12 / 1
F = 72 N
3-15
If a 5 kg bowling ball4-25A
is spun vertically at 24m/s,
attached to a 0.5m rope, what is the tension on the
rope at the bottom of the circle?
If a 5 kg bowling ball is spun vertically at 24m/s,
attached to a 0.5m rope, what is the tension on the
rope at the bottom of the circle?
Ft - Fg = mv2 / r
Ft = 5*242 / .5 +5*9.8
F = 5809 N
Ft
Fg
3-20
If one moon orbits a planet at a radius of
400,000 km, and has a period of 30 days,
how long will it take a moon to orbit the
planet at half the radius?
3-20A
If one moon orbits a planet at a radius of
400,000 km, and has a period of 30 days,
how long will it take a moon to orbit the
planet at half the radius?
Ra3/Ta2 = Rb3/Tb2
400,0003/302 = 200,0003/Tb2
T = 10.6 days
3-25
In a carnival ride which spins you in a vertical
circle, how fast must it spin for you to feel
weightless at the top if it has a radius of 2m?
3-25A
In a carnival ride which spins you in a vertical
circle, how fast must it spin for you to feel
weightless at the top if it has a radius of 2m?
Fg + Fn = mv2 / r
Fn = 0
mg = mv2 / 2
Sqrt(2g) = v
v = 4.43m/s
2-15
4-5
A baseball thrown4-5A
horizontally from
the pitcher’s mound travels 145 kph
before hitting the ground 1.5 sec later.
How far (in meters) is it from the
mound to where the ball hits?
A baseball thrown horizontally from
the pitcher’s mound travels 145 kph
before hitting the ground 1.5 sec later.
How far (in meters) is it from the
mound to where the ball hits?
vx =145 km/hr (1000 m/km) (hr/3600 sec) = 40.3 m/sec
 dx = vx t = (40.3 m)(1.5 sec) = 60.4 meters
A softball is tossed horizontally from a
treehouse 4 meters tall, and the ball lands 20
meters from the treehouse. How fast was the
ball thrown?
A softball is tossed horizontally from a
treehouse 4 meters tall, and the ball lands 20
meters from the treehouse. How fast was the
ball thrown?
dx = vxt and
dy = (1/2)at2
 t = √(2 dy/a)
 where  dy = 4 m
t = √[2(4 m)/(10 m/s2] = 0.894 sec
v = dx / t = 20m / 0.894 sec
v = 22.4 m/s
A water balloon is launched up at 6.5 m/s
and sideways at 4 m/s. How far
(horizontally) does it travel before hitting
the ground?
A water balloon is launched up at 6.5 m/s
and sideways at 4 m/s. How far
(horizontally) does it travel before hitting
the ground?
vfy = viy + at,
vfy = 0 m/s (top) ==> -viy = at
t = -viy / a ==> t = (6.5 m/s) / (-10 m/s2) = 0.65 sec
time of flight = 2t = 1.3 sec
dx = vxt = (4 m/s)(1.3 sec) = 5.2 meters
If an object is launched upwards at 24 m/s
and sideways at 12 m/s, how much time will
it take before it reaches the top?
4-20A upwards at 24 m/s
If an object is launched
and sideways at 12 m/s, how much time will
it take before it reaches the top?
vf = vi + at
(vf = 0 m/s)
=> t = -vf / a
t = -(24 m/s) / (-10 m/s2) = 2.4 sec
A water balloon is launched with a
horizontal velocity of 10 m/s and a
vertical velocity of 8 m/s. What is the
balloon’s velocity at the top of its
path?
A water balloon is launched with a
horizontal velocity of 10 m/s and a
vertical velocity of 8 m/s. What is the
balloon’s velocity at the top of its
path?
10 m/s horizontally because
the horizontal velocity of a
projectile is constant
How can a pants pocket have
something in it and still be empty?
How can a pants pocket have
something in it and still be empty?
It can have a hole in it.
You throw away the outside, then cook
the inside, then eat the outside, then
throw away the inside. What is it?
You throw away the outside, then cook
the inside, then eat the outside, then
throw away the inside. What is it?
Corn on the cob.
Name the movie which
gave us this
5-15
quote:
“Looks like you’ve been missing a lot
of work lately”
“I wouldn’t say I’ve been missing it,
Bob.”
Name the movie which gave us this
quote:
“Looks like you’ve been missing a lot
of work lately”
“I wouldn’t say I’ve been missing it,
Bob.”
Office Space
5-20
What is the largest land carnivore in
the world?
What is the largest land carnivore in
the world?
Polar Bear or Kodiak bear
What giant monster5-25
was once
described as a cross between
a Gorilla and a Whale, and in
fact who’s name was a blend
of these two words…
(in another language)?
What giant monster was once
described as a cross between
a Gorilla and a Whale, and in
fact who’s name was a blend
of these two words…
(in another language)?
Godzilla
Gorira & Kujari = Gojira