Download Thursday, Dec. 11th Thursday, Dec. 11th

THURSDAY, DEC.
p. 106, 107
TH
11
106
12/11/14 Thurs.
L.T.: I can write a 3 part hypothesis
and a procedure to investigate the
average speed of rolling objects.
DO NOW: Al and Zane both need to
travel 1 mile to get to school. Both
arrive at school in 15 mins. but
traveled at different average speeds.
How could this be?
………………
Reflection Qs:
What is the difference between
constant speed and average speed?
Use something from class to back up
your answer.
Title: Need for Speed 2
Speed
Rankings:
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Q: How do the avg. speeds of various
rolling objects compare over the
course of 1 meter?
Hypothesis: If… then… because…
Procedure: includes 3 variables and
numbered, logical steps
THURSDAY, DEC. 11TH

Variables:

RV: time (so that we can calculate speed: speed = d/t)

MV: different rolling objects of dif. Masses

CV: track (1 m), ramp height and length, release point at top of
ramp with no added force,
5TH PERIOD

Variables:

CV: positioning of the ramp, “release” of ball – no added force,
same release point (top of ramp), length of track (1 m), how we
gather data (start timer at beginning of meter; stop at end of 1
m)

MV: mass of rolling object

RV: time (so that we can calculate speed S = d/t)
4TH PERIOD

Variables:

CV: ramp angle (3 books tall, purple line on book edge), ball
needs to roll to the end of 1 meter, length of track (1m), surface
of track (tabletops), “release” of rolling object

MV: mass of rolling object

RV: time, so that we can calculate speed (meters/sec)
3RD PERIOD

If you increase the mass of the rolling object,

Then its speed after rolling down a ramp will (1)
increase? 2) Decrease? 3) Stay the same?)

Because…

1) normal force and gravity creates more
acceleration.

2) bigger mass has more sliding friction, so
slower speed.

3) the friction and elevation is the same
5TH PERIOD HYPOTHESIS

If the rolling object has more mass,

Then its speed after rolling down a ramp will be
greater,

Because:

- the combined normal force and gravitational
pull will make a bigger force downhill on a
larger mass than a smaller mass

- a larger mass will have more force to
overcome sliding friction
HYPOTHESIS

Hypothesis:

If we roll round objects of different mass,

Then the more massive ones will move with (less)
speed,

Because the object with more mass needs
more force to overcome friction.

Because the bigger the mass the less
acceleration of the object.

Because the more mass the ball has the less
speed it will go compared to a smaller (massed)
ball.
3RD PERIOD

Mass of rolling objects:

Basketball:

Volleyball

Softball:

Baseball:

Ping pong ball:

Steel marble:

Procedure:

CV:

MV:

RV:

1. Gather materials.

2. Set up ramp with science books: 3 on bottom, 1
on top. Line up top book’s purple stripe to the
spines of the stacked pile.

3.
FINISH FOR HW