Download Answers Review Newton`s Laws Assessment

Answers for Review of Motion & Newton’s Laws Test
1) Frogy: Speed =
Velocity =
200m
m
8
25 sec
sec
100m
m
4
East
25 sec
sec
Momentum = 5kg  4
m
m
East  20kg 
East
sec
sec
4) When traveling south to L.A. Jaydee averaged a velocity of 50 km/hr. After he had traveled for
500 km, how long had Jaydee traveled for?
d
km 500km
V
50

 10 hr
t
hr
t
Roller Coaster
words when you use them.
dis tan ce – Is defined as distance traveled in a given time. The marble built up
time
speed due to gravity as it was traveling down the ramp. Its speed is
slowed due to friction or when it went up hill. So if an object went 1 meter in 2.5 seconds then you
divide 1 meter by 2.5 seconds which works out to 0.4 m/s. It is important they remember the
units…no units no credit.
Speed
Speed 
Velocity –
Velocity 
Is defined as speed (distance over time) along with a
dis tan ce
w / direction
direction. So anytime the marble changed directions
time
its velocity changed which also caused a change in
acceleration.
Mass  velocity
Momentum
– Momentum is defined as the velocity of an object multiplied by the
mass of the object. Objects with a heavy mass moving at the same speed have much more
momentum than object moving at the same velocity with very little mass.
Conservation of Momentum or Inertia– Conservation of Momentum or inertia is defined as objects in
motion want to stay in motion moving in a straight line (velocity) unless acted upon by another
force and an object that is stationary will stay that way until acted on by an outside force.
(This was why the marble went against gravity and went upside down in the marble roller coaster.
The marble’s momentum wanted to continue moving in a straight line. If your group gradually
changed the direction until the marble was going upside and the marble had enough velocity then it
would go around the loop. If your group did not change the direction gradually then you lost your
momentum to friction and the marble did not complete its loop. Also if your marble did gather up
enough momentum because your ramp leading up to your loop was too short then your marble also
would not make it around the loop.)
Gravity & Acceleration – Gravity is simply defined as the earths pull on an object (this definition will
change for those who take physics). Acceleration is defined as the change in velocity. If I increase
speed (therefore changing my velocity) without changing direction I am accelerating, this how you
usually think of acceleration. But if I drive my car around a corner without changing speed I am
still accelerating because I have changed direction which means I have also changed velocity. And
of course if I change my speed and direction I am accelerating.
Friction – Friction is the force that pushes against a moving object. Any time the marble changed
directions it encountered friction because it is interacting with surface of the paper. If there was
tape on the ramp or any unsmooth surfaces this causes additional friction.
Force – The cause of acceleration, in this case gravitational force.
 Why does the marble go upside down?
The marble goes upside down because of inertia. As the marble accelerates due to gravity pulling on the
marbles mass it builds up momentum. Inertia means that the marble wants to maintain its momentum
going straight. If you gradually change the marbles direction you can get it to go upside down because
the marble’s momentum or inertia carries it through the loop.
 What causes the marble to accelerate and de-accelerate?
As the marble goes down the ramp it accelerates do to gravity or earth’s pull on the marble. The marble
starts out with 0 velocity and increases it’s velocity or accelerates. Friction caused by the surface of the
ramp and the marble causes the marble to slow. The smoother the ramp the faster the marble goes
because there is less friction to decrease the momentum. Also, when the marble goes up the hoop, it slows
a bit due to gravity, and then accelerates a bit as it goes down the hoop due to gravity.
4) Give two more examples of when inertia might have an impact on your life?
 When you hit your breaks while driving your inertia causes your head to jerk forwards.
 While in a car when you turn left your body swerves to the right because it wants to continue moving
straight.
Ramp and Car Lab/ Test
Essential Question: What causes a car to accelerate?
Hypothesis: (If, then, because) If the mass of the car increases then the car will go faster because gravity
will cause pull more on the more massive car.
Manipulated Variable (Independent): increasing the mass of the car
Responding Variable (Dependent): amount of time spent on the ramp
Constant or Controlled Variables: - length of the ramp, type of car, height of the ramp
Materials:
1. ramp
2. car
3. books
4. Timer
Procedures:
1. Stack 10 books up.
2. Place ramp on books. Measure the height of the ramp to ensure that it is at 80 cm height.
3. Measure the mass of the car.
4. Place car on top of the ramp.
5. Time car from start to finish on the ramp three times.
6. Increase the mass of the car by 100 grams.
7. Time the car from start to finish on the ramp three times.
8. Increase the mass of the car by 100 grams.
9. Time the car from start to finish on the ramp three times.
10. Increase the mass by another 800 grams to a total of 1255 grams.
11. Increase the mass of the car by 100 grams.
12. Time the car from start to finish on the ramp three times.
Observations:
The car ran smoothly from beginning to end. Sometimes the car ran off the track so we had to do it
again. Weights had to be tapped to the middle of the car to get them to stay on.
Car Mass
Trial 1 – Time (sec)
Trial 2 – Time (sec)
Trial 3 – Time (sec)
Avg. – Time (sec)
255 g
7.2
7.1
6.9
?
355 g
6.8
6.9
6.7
?
455 g
6.1
6.1
6.0
?
1255 g
4.5
4.6
4.8
?
Complete a graph from the data on the front.
Data Analysis:
My graph and data show that as I increased the mass the time decreased. I started out with 255 grams
and my average time was 7.1 sec when the car with a mass of 1255 g had an average time of 4.7 sec.
Conclusion:
The purpose of the lab was to determine what causes a car to accelerate. After conducting this
experiment one can determine what can affect a cars gas mileage. The hypothesis in the experiment
was If the mass of the car increases then the car will go faster because gravity will cause pull more on
the more massive car. The hypothesis was supported by the data. The data showed that with 255
grams and my average time was 7.1 sec when the car with a mass of 1255 g had an average time of 4.7
sec. This was an decrease of 2.4 sec. My times were a little different showing that there was some
experimental errors. Most of the errors probably occurred with starting and stopping the timer aligning
with starting and stopping the car. For future experiments I want to look at what might happen if I add
oil to the axle to decrease the friction of the car.
7) Combustion – What are some things that burn? When any of these fuels burn what do they react
with and what do they form. Also, when these fuels burn, where does the energy come from?
Any fuel such as oil, wood, and paper all react with oxygen (O2) to form carbon dioxide (CO2) and
water (H2O). CH4 + O2 => CO2 + H2O
8) Bonding - Draw NH3 showing the covalent bonds.
9) Drawing Atoms – Draw Calcium showing protons, neutrons, and electrons.