Transcript 100 - Answer - GEOCITIES.ws

Physics
Pretend-to-be-Jeopardy
Time to Fly
Graphing
Physics
Life at NSAA
Fantastic
Forces
100
100
100
100
100
200
200
200
200
200
300
300
300
300
300
400
400
400
400
400
500
500
500
500
500
600
600
600
600
600
Everyday Stuff
Final Jeopardy
Everyday Stuff...
100

I saw an orange fall from a tree.

What was it’s acceleration?
Everyday Stuff...
100 - Answer
9.8
2
m/s
Everyday Stuff...
200
A raindrop falls from the sky. It
starts from rest somewhere in the
clouds. It hits the floor at 100 m/s.
How far did the drop fall?
Everyday Stuff...
200 - Answer
510 m
vf2= vi2 + 2a∆x
Everyday Stuff...
300
Yesterday I saw people on TV trying to sound
smart using this problem: Train A leaves the
station traveling at 20 m/s. Train B leaves the
station traveling at 35 m/s. Both trains travel
at a constant velocity. Stations A and B are
175 m apart. After how many seconds do the
trains cross paths, assuming they are
traveling to the opposite station?
Everyday Stuff...
300 - Answer
We know that they are at the same location
when the cross, so final positions are equal.
A
B
xf= xi + vt
xf= xi + vt
xi + vt = xi + vt
0m + (20m/s)t
= 175m + (-35m/s)t
(55m/s)t = 175m
t = 3.18s
Everyday Stuff...
400
A student wanted to find out if the temperature
of water affected the amount of sugar that
would dissolve in it. He put 50 mL of water
into each of four identical jars. He changed
the temperatures of the water in the jars until
he had one at 0°C, one at 50°C, one at 75°C,
and one at 95°C. He then dissolved as much
sugar as he could in each jar by stirring.
What is the relationship being studied?
Everyday Stuff...
400 - Answer
The effect of higher temperature on the
amount of sugar dissolved.
Everyday Stuff...
500
a
Everyday Stuff...
500 - Answer
a
Everyday Stuff...
600
In Physics, what are the standard units for
measuring
Time
2. Distance
3. Velocity
4. Acceleration
1.
Everyday Stuff...
600 - Answer
Time: seconds (s)
2. Distance: meters (m)
3. Velocity: m/s
2
4. Acceleration: m/s
1.
Launching Things!
100
Launching Things!
100 - Answer
a
Launching Things!
200
a
Launching Things!
200 - Answer
a
Launching Things!
300
A diver running at 3.6 m/s dives out
horizontally from the edge of a
cliff and reaches the water below
2.5 s later. How high was the
cliff?
Launching Things!
300 - Answer
30.63 m
Launching Things!
400
A ball player wishes to determine her
pitching speed by throwing a ball
horizontally from an elevation of 4.0
m above the ground. She sees the
ball land 25. m down range. Determine
the speed of the ball as it leaves her
hand
Launching Things!
400 - Answer
27.8 m/s
Launching Things!
500
A daredevil tries to jump a canyon of width 10
m. To do so, he drives his motorcycle up an
incline sloped at an angle of 15 degrees.
What minimum speed is necessary to clear
the canyon?
Launching Things!
500 - Answer
14.18 m/s
Click here for solution
Launching Things!
600
A long jumper leaves the ground with
an initial velocity of 12 m/s at an
angle of 28-degrees above the
horizontal. Determine the time of
flight, the horizontal distance, and
the peak height of the long-jumper.
Launching Things!
600 - Answer
Flight Time: 1.1 seconds
Horizontal Distance: 12.2 meters
Peak Height: 1.6 meters
click here for solution
Graphing!!!
100
Do the cyclists
start at the
same point?
How do you
know? If not,
which is
ahead?
Graphing!!!
100 - Answer
No… Cyclist B starts ahead.
The y-intercept gives his
position at time = 0s… or the
start.
Graphing!!!
200
Determine the
object's average
velocity.
Determine the
object's position
at t = 10
Graphing!!!
200 - Answer
Avg Velocity:
5 m/s
At t=10s, will be at 60
m
Graphing!!!
300
Determine the displacement for the first
three seconds for each object.
Object W
Object J
Graphing!!!
300 - Answer
Object W
9 meters
Object J
9 meters
Go figure…. 
Here is a position v.
time graph for an
object. Would it be
more accurate to
describe the velocity in
terms of average
velocity or
instantaneous velocity?
How would you find the
one you choose?
Position (m)
Graphing!!!
400
Time (s)
Graphing!!!
400 - Answer
Instantaneous Velocity
Draw a tangent line at a specific point. The
slope of that tangent line will be the
velocity at that instant in time.
Graphing!!!
500
Sketch a (1) velocity v. time graph and
(2) acceleration v. time graph
x
B
Position (m)
C
A
t
Time (s)
D
E
G
F
Graphing!!!
500 - Answer
Acceleration v. Time
Velocity v. Time
A
B
C
D
E
F
G
A
B
C
D
E
F
G
Graphing!!! - 600
Assume that the ball does not experience any
change in velocity while it is on a horizontal portion
of the rail.
Produce the following graphs:
(1)Position v. Time, (2) Vel. v. Time, (3) Accel. v. Time
Acceleration
Velocity
Position
Graphing!!!
600 - Answer
Physics Life at NSAA
100
A very scared senior that was just caught
ditching is running from Mr. Walker. The
student accelerates from rest to a speed of
28 m/s in 20 s. (Apparently fear makes you
go fast.)
What is the acceleration of the senior?
Physics Life at NSAA
100 - Answer
2
m/s
1.4
vf = vi + a∆t
Physics Life at NSAA
200
A student really needs to use the restroom in
class but the teacher won’t let him go for 15
minutes. After the 15 mins are up, the
student, starting from rest, accelerates at a
rate of 6.0 m/s2.
If the restroom door is 16 m away, how fast
will the student be going as he reaches the
door?
Physics Life at NSAA
200 - Answers
13.9 m/s
vf
2=
+
2
vi
+ 2a∆x
Physics Life at NSAA
300
A dancer is practicing for winter
performance. She has her I-pod in and is
not paying attention. Starting from rest,
she moves across the stage accelerating
at a constant 1.0 m/s2.
She plans on continuing to move that way
until the song is over in 6s. The stage is
15m wide. Is she going to fall off the
stage?
Physics Life at NSAA
300 - Answer
Yep…. She won’t stop for 18m.
Moral of the story: Pay attention.
Physics Life at NSAA
400
A skateboarder is skating at a velocity of 6
m/s when a wheel falls off causing him to
slow down at a uniform rate of 0.5m/s2.
How fast will he be skating after going an
additional 13 meters?
Physics Life at NSAA
400 - Answer
4.8 m/s
vf
2=
+
2
vi
+ 2a∆x
Moral of the Story: Take care of your stuff.
Physics Life at NSAA
500
A student wants to show off her freshly restored
1967 Shelby Mustang. She burns out of the
parking lot going from rest to 36 m/s
(≈60mph) in 4 seconds. The car's velocity
changes at a constant rate. What is the car’s
acceleration? How fast will the car be going
3.0 seconds after it starts?
Physics Life at NSAA
500 - Answer
9
2
m/s
vf = vi + a∆t
27 m/s
Physics Life at NSAA
600
A guy wants to scare his friend. He drives a car
at a constant speed of 25 m/s directly at his
friend, with the intention of stopping just
before him. His friend is 150 m away when
the driver hits the brakes and beings to
accelerate uniformly at a rate of 0.63m/s2.
Will the car come to a stop as the driver
intended, or should we call an ambulance?
Physics Life at NSAA
600 - Answer
The friend is safe. (Solve for the distance he went
if his final velocity is 0 m/s, his initial velocity is
25 m/s, his acceleration is -0.63 m/s2.)
The driver stopped after 99.2 m….. 0.8m short.
vf
2=
+
2
vi
+ 2a∆x
If you try to solve for the final velocity at 100m you
will end up having to take the square root of a
negative number (it wont work.. Because he had
no velocity at 100 m/s)
Forces
100
A 4600 kg helicopter accelerates
upward at 2.0 m/s2. What lift force
is exerted by the air on the
propellers?
Forces
100 - Answer
54280 N
FL: Force lifting helicopter off ground
ΣF = FL – FE = ma
FL – (4600kg)(9.8N/kg) = (4600kg)(2m/s2)
FL = 9200 N + 45080 N
FL = 54280 N
Forces
200
A race car has a mass of 710 kg. It starts
from rest and travels 40.0m in 3.0s. The
car is uniformly accelerated during the
entire time. What net force is acting on
the car?
Forces
200 - Answer
6305 N
(1) Find Acceleration
xf = xi + vit + ½ at2
(2) Find Net Force
ΣF = ma
Forces
300
A 65 kg person dives into the water from the 10
meter high platform.
a) What is her speed as she enters the water?
b) She comes to a stop 2.0 m below the surface
of the water. What net force did the water
exert on the swimmer?
Forces
300 - Answer
14 m/s, 3185 N
vf2 = vi2 + 2a∆x
ΣF = ma
Forces
400
Suppose that a 1000 kg car is traveling at 25
m/s (≈55 mph). Its brakes can apply a force
of 5000N. What is the minimum distance
required for the car to stop?
Forces
400 - Answer
62.5 m
Find Acceleration
ΣFx = max
Find Distance
vf2 = vi2 + 2a∆x
Forces
500
A 10 kg block is allowed to slide
down a ramp with uk = 0.15.
a. What is the value of the
frictional force opposing the
block's slide down the ramp?
b. What is the acceleration of the
block?
Forces
500 - Answer
Fk = 13.8 N
2
a = 1.97 m/s
Forces 600
A 70.0 kg box is pulled across a frictionless surface by a
300. N force at an angle of 30.° to the horizontal.
What is the acceleration of the box in the x-direction?
What is the normal force on the box?
Forces
600 - Answer
2
m/s
ax = 3.71
FN = 536 N
Final Jeopardy
Final Jeopardy - Answer
…….