Transcript Bell Ringers

Bell Ringers
Bell Ringer
Aug 14, 2012
• Grab an article from the box and read it.
Don’t get lost in the unusual names or
words. Simply highlight/underline them
and move on. Then use the back to
analyze the story.
*Remember, I expect you silent during
the bell ringer.
Bell Ringer
Aug 15, 2012
• Grab a fishboning explanation and
guide from the “box”. Use the article
from yesterday(fire in the lab) and use
the fishboning method to:
– Write the main idea
– Support your idea
– Give take away message
*Remember, I expect you silent during
the bell ringer.
Bell Ringer
Aug 16, 2012
Questions for the Author
• Grab the reading strategy from the
“box”. Read it and do it using the “Fire
in the lab” story from Tuesday.
*Remember, I expect you silent during
the bell ringer.
Bell Ringer
Aug 17, 2012
A safe lab culture article
• Grab the article from the “box”. Read it.
*Remember, I expect you silent during
the bell ringer.
Bell Ringer
Aug 20/21, 2012
• If it takes one second for light to travel
from the moon to the earth and 8
minutes for light to travel from the sun
to the earth, how far away are the moon
and sun?
Bell Ringer
Aug 22/23, 2012
• Write as many scalar quantities as you
can think of.
• Write as many vector quantities as you
can think of.
• Find the component form of the
following vector.
Bell Ringer
Aug 24/27, 2012
• We are going to the library.
• You will need to create:
1. Gmail account
2. Edmodo account
3. Dropbox account
Bell Ringer
Aug 30/31
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What is gravity?
Where does it come from?
What kinds of things have gravity?
I have two masses. One is a basketball. The other
is a 5lb bag of potatoes. If I hold them at the
same height and drop them at the same time,
which one hits the ground first?
• Do they have a constant velocity?
• Do they have the same gravitational force acting
on them?
Bell Ringer Sept 4/5
• Consider the graph at the right. The object whose
motion is represented by this graph is ... (include all
that are true):
1. moving in the positive direction.
2. moving with a constant velocity.
3. moving with a negative velocity.
4. slowing down.
5. changing directions.
6. speeding up.
7. moving with a positive acceleration.
8. moving with a constant acceleration.
Bell Ringer Sept 6/7
• A car (A) moves to the left with speed 40km/h
(with respect to the road). Another car (B) moves
to the right with speed 60km/h(also with respect
to the road). Find the relative velocity of B with
respect to A.
• After 5s a car is moving 20km/h. It uniformly
accelerates to 60km/h in 15s. If the car were to
continue to accelerate at the same rate how fast
would it be going after a total time of 1 min. Use
a graph to estimate the value.
• An ice cube melts at a constant rate. For every
increases of 3degress in the room
temperature ice will melt 6ml of water. Use a
graph to determine the how much ice has
melted if the room temperature has increased
a total of 13degress.
• A car (A) moves to the left with speed 40km/h
(with respect to the road). Another car (B)
moves to the right with speed 60km/h(also
with respect to the road). Find the relative
velocity of B with respect to A.
Sept. 17/18
• What is a force?
http://www.youtube.com/watch?v=GmlMV7bA
0TM&feature=relmfu
• Why does the Earth spin? Explain.
http://www.youtube.com/watch?v=TQxeutcYP6I
&feature=edu&list=PL772556F1EFC4D01C
• If you stopped the Earth from spinning, would
it stay stopped or not? Explain.
Sept 19
• What are Newton’s Three Laws?
• What is wrong with Derrick’s Laws
Sept. 25/26
• What is momentum? Example.
• What is impulse? Example.
• What is the Law of Conservation of
Momentum? Example
Sept 27/28
A motorboat traveling 4 m/s, East encounters a
current traveling 3.0 m/s, North.
1. What is the resultant velocity of the motorboat?
2. If the width of the river is 80 meters wide, then
how much time does it take the boat to travel
shore to shore?
3. What distance downstream does the boat reach
the opposite shore?
http://www.physicsclassroom.com/class/vectors/u3l1
f.cfm#soln
(See examples 1 and 2 for explanations)
Oct 1/2
At a railway station, two trains slowly collide in
order to “couple” (join together). If one train
of mass 12000kg is moving at 0.75m/s and the
other of mass 3000kg is stationary, calculate
the velocity of the two as they move away.
Answer: 0.6m/s
Oct 3/4
• Ball A travelling with speed V in the direction shown
makes a glancing collision with stationary ball B of
the same mass. After the collision the balls move
off with speeds Va and Vb in the directions show on
board. Which one of the following is true? Explain.
• A) Va cosα = Vb cosβ
• B) Va sin α = Vb singβ
• C) V = Va cosα + Vb cosβ
• D) V = Va + Vb
• Answer: A
• Since momentum is a vector quantity,
direction is also conserved i.e. momentum in
the +x to –x direction = 0. Va cosα = Vb cosβ
Oct.5/8
Come in have a seat.
Expected grades.
We have a force quiz – 30min
Start collision lab – 45min
Oct. 9/10
1.
2.
3.
4.
Define weight
What is Newton’s 3rd Law
Use the given triangle to solve for “x”
Add the following vectors:
a) 4m/s @45deg
b) 9m/s @150dg
Oct. 11/12
1. A 0.1kg ball moves at 5m/s bounces off a vertical
wall without a change in its speed. If the collision
with the wall lasted for .1s what force was
exerted on the wall?
2. A ball of mass.25kg moves on a frctionless
horizontal floor and hits a vertical wall with
speed 5m/s. the ball rebounds with speed 4m/s.
If the ball was in contact with the wall for .15s,
find the average force that acted on the ball.
3. Bullets of mass .03kg are being fired from a gun
with a speed of 300m/s at a rate of 20 bullets per
second. What force is being exerted on the gun?
Oct 16/17
• A man of mass “m” stands on a cart of mass “M”
that rests on a horizontal frictionless surface. If the
man begins to walk with velocity “v” with respect to
the cart, how will the cart move?
• What happens when the man gets to the edge of
the cart and stops walking?
Oct 22
• A stationary body(A) of mass 12kg is hit
by a 4kg mass(B) moving at a velocity of
12m/s. Body A moves off at an angle of
60degree to the left of the original
direction. Body B moves off at an angle
of 30 degrees to the right of the original
direction.
• What are the speed of the two masses after
the collision?