Transcript Activity 77 Major Concepts • There is a direct relationship between mass of a moving object and the force it can apply on.

Activity 77 Major Concepts
• There is a direct relationship between
mass of a moving object and the force it
can apply on another object.
• Good experimental design requires
keeping as many variables as possible the
same - except the one being tested – so
that any results can be attributed to the
variable change.
• Mass did not have an effect on speed.
Activity 78
Title: Force, Acceleration,
and Mass
Read E-21
• Problem: What is the mathematical
relationship between force, acceleration,
and mass?
• Hypothesis: Just answer the question. Do
not use an if/then statement.
Review Acceleration:
• What is acceleration?
Acceleration occurs when an object
speeds up, slows down, or changes
direction. An object moving at constant
speed and direction is not accelerating.
You can also say acceleration is a change
in motion.
Speed vs Acceleration
• Although speed and acceleration are both
rates that describe motion, they are not the
same thing. Speed is the rate at which
distance is traveled, whereas acceleration
is the rate at which speed is changing. An
object that has a larger rate of speeding up,
as opposed to simply a high rate of speed,
has a higher acceleration.
Example:
• A car moving at a constant speed
of 60 mph (no acceleration)
• A car that moves from zero (0) to
20 mph in 5 seconds (acceleration
of 4 mph).
What are the SI units for the following
measurement? Copy into your notebook.
Background information:
SI unit for:
• Speed
Meters per second (m/s)
• Mass
Kilograms (kg)
• Acceleration
m/s2 {can be written as m/s /s, which is speed
(m/s) divided by time (s) }.
• Force
newton (N)
newton (N)
• The unit is named after Isaac Newton.
One newton is about equal to the
downward force (weight) of a 100-gram
mass near the surface of Earth.
The Activity:
• Thoroughly read the procedure on pgs
E-22 to E-23. Set your notebook up as
follows:
Data:
Part A: Comparing the Variables
Follow procedure 1-3 and include all
required information under the Part A
heading (including analysis question 1).
After most students have finish Part A, share
with the class your answers to analysis #1.
After the class discussion,
continue with parts B and C.
Part B: Find the Equation
procedure 4
Part C: Double-checking the Equation
procedure 5 and 6
Discuss Results:
• The equation, F = 2a works for the first set of
data because this data set is based on a 2 kg
mass.
• It does not work for Experiment 2 in part C,
which is based on a 4-kg mass.
• “2” in the equation, F = 2a is the mass, which
would have to be a 4 in Experiment 2.
The generalized equation which
works for both is:
F = ma
The relationship can be written in 3 ways:
F = ma
a=
F
m
This relationship between force,
acceleration and mass is known
as Newton’s Second Law
m=
F
a
Write all this
in your data
section
For the rest of the period:
• Watch a Bill Nye video on motion.
Answer the questions on the sheet
provided. It will be turned in for a grade.
• Do Activity 78, analysis 1-5
Give thorough answers to your
questions and compare your answers
with your group.
• Read pg. 350-355 in PH and answers
question 1-5 on pg. 355 on separate
paper.