Transcript Unit 4 NonInertial Reference Frames_ap1x

Non-Inertial
Reference
Frames
Unit 4
section 6.6 and 6.7
Frames of Reference
Watch this masterpiece filmed in Toronto in 1960.
Frames of Reference Introduction
Inertial Reference Frames
An electromagnetic holds up a steel ball.
When the current stops, the ball falls due to
gravity.
Inertial Reference Frames
The electromagnet and stand are mounted on a cart
with wheels attached to a track.
Predict the trajectory of the marble if
1. The cart is moving at constant velocity on the
track while the camera is mounted on the table?
2. The camera and electromagnet are both on the
cart moving at constant velocity relative to the
table.
Link to video (start at 5:45)
Inertial Reference Frames
• In which frame of reference do Newton’s
Laws hold true?
• Prove this with a force diagram.
Inertial Reference Frames
• Newton’s Laws of Motion are obeyed in
inertial frames of references.
• Inertial frames of reference move at
constant velocity relative to each other.
• They are all equally valid.
Non-Inertial Reference Frame
In this experiment the camera is mounted on the cart
with the marble and electromagnet. The cart is them
tied to a string with a mass attached. When released,
the stand, electromagnetic and marble accelerates to
the right. During this period of acceleration, the
marble is released.
Predict the motion of the marble as captured by the
camera on the cart. Link start at 13:15
Non-Inertial Reference Frame
Draw a diagram of
the forces acting on
the marble. Can its
motion be explained
by the forces?
Car Pendulum
Draw a force diagram for the
pendulum in the video.
Compare your diagram with
your partner and discuss.
Smarter Everyday
Merry Go Round
Watch the motion of the puck in the different
frames of reference. Draw a force diagram for
each frame of reference.
In which frame of reference are Newton’s
Laws valid? Which frame does a fictitious
force appear to be exerted on the puck?
Watch the puck
Do Newton’s Laws always apply?
• Think about the three videos we just watched.
Summarize what you witnessed.
• Did you notice any patterns?
• Watch this and explain the strange motion of the
basketballs.
Accelerating Reference Frames
• Examples: a car speeding up, a merry go round
spinning, a bus slowing down
• What is the space station doing?
• Why does the camera appear to accelerate?
Thrust on board the International Space Station
Question 8
A space station has an inner radius of 100 meters and
an outer radius of 140 m. The station rotates at one
revolution every 20 seconds. What is the apparent
weight of a 50-kg person and the apparent gravitational
field (a) at X (b) at Y?
Answer
(a) 690 Newtons 13.8 m/s2
(b) 494 Newtons 9.9 m/s2
On board a rotating space station - DO NOT
READ THE TEXT!!! IT IS SO WRONG!!!!
An Experiment
Two 1-kg carts are
pulled across the
track with a force
sensor. The
Capstone software
records the force and
speed of the carts vs
time. Two graphs
show the data on the
next page.
Data
Apparent Weightlessness
• Inside the International Space Station
• Watch this video of astronauts aboard the
International Space Station (ISS).
• Draw a force diagram of the force(s) acting on the
astronaut? Is the force diagram consistent with the
motion?
• What is the apparent value of the acceleration due
to gravity? Then, calculate the value of the
acceleration due to gravity, g, at the ISS’s height
(350 km) above the earth’s surface.
• How do you explain the discrepancy?
Example
A scientist in the International Space Station experiences apparent
weightlessness because
(A) there is no gravitational force from the Earth acting on her.
(B) the gravitational pull of the Moon has canceled the pull of the Earth
on her.
(C) she is in free fall along with the Space Station and its contents.
(D) at an orbit of 200 miles above the Earth, the gravitational force of
the Earth on her is 2% less than on its surface.
(E) in space she has no mass.
Angry Birds & Pigs in Space