Homework Solutions 12/19

86. KE = 1/2mv^2 = .5(10)(10)^2 = 500J
87. F = ma = m (change in v/change in t) = m (10/4) = 25N
88. Change in KE = F*d --> 500J = 25 * d --> d = 50m
89. (1) Less
90. (2) increases
91. (1) less than h
92. It would look like a graph of y = x^2, a parabola
93. KE = .5(1)(100) = 50J; 50 = 1*10*d --> d = 5m

Exam 6 Review Sheet Solution

1. 70N
2. 300J
3. half as great
4. 300W
5. 800J
6. 10J
7. quadruples
8. 125J
9. BC
10. 3J

Homework - Week of 12/17

Monday: TPS p89 77-85
Tuesday: TPS p90 86-93
Wednesday: STUDY!!! (tutoring session Wednesday period 5 in room 606)
Friday: Take home Regents exam for the break

Answers to Friday's Review Sheet

1. D
2. B
3. A
4. C
5. D
6. B
7. C
8. C
9. C
10. D
11. D
12. C
13. A
14. C
15. B
16. A
17. A
18. D
19. D
29. A
21. D
22. A
23. A
24. C
25. A
26. B
27. A
28. D
29. D
30. C
31. C
32. D
33. B
34. B
35. D
36. A
37. D
38. B
39. A
40. C
41. B
42. A
43. D
44. A

For Monday's Lab

1. The energy lab is due
2. Bring your structural support materials for your roller coaster

Solutions to Review Sheet

1. 150J
2. the same
3. 3.0kg-m/sec
4. 7.5 m/s West
5. 24J
6. 5J
7. 8 x 10^2 Joules
8. momentum
9. 48 kg-m/sec north
10. greater

Conservation of Momentum Answers

1/2: 16.9 m/s
3/4. 5 m/s
5. 7 cm/s
6. 1.15 m/s
7. 58 cm/s
8. 1.25 km/hr right
9. 1.14 m/s E

Corrections to Solutions

It appears my copy of the review sheet was different than yours. I have put the solutions below in the order the questions appear on your copy. Email me with any questions.

1. 0 Degrees (180 degrees is minimum resultant, 0 degrees is maxiumum)
2. Arrow up and to the right (use the parallelogram method)
3. 100N (use change in velocity - 10m/s, over change in time - 1.5 s to find acc., then multiply by mass to find the force)
4. 44m (use d = Vit + 1/2at^2, where a = 9.8, t = 3, Vi = 0)
5. decrease (remember because F = Gm1m2/r^2, the distance r plays a greater factor)
6. F (Force of friction only relies on Normal force, and coefficient of friction)
7. Arrow from the box, down and to the left, parallel to the plane (friction always opposes motion)
8. DE (this is where the slope of distance v. time is NOT constant, so velocity must be changing)
9. 10 m/s^2 (use v^2/r, NOT mv^2/r, because we are finding acceleration, not force)
10. copper (its coefficient is the smallest value).
11. 2.0s (Find the average acceleration (Vf + Vi)/2 , then use d = V*t to find t)
12. 1 x 10^ -2 N (mass of insect x velocity of insect)
13. 40m (use Vf^2 = Vi^2 + 2ad)
14. .2h (use distance = average velocity * time)

Solutions to Midterm Review Sheet - Reminder Tutoring

Tutoring
Room 203 - Period 5 - With Ms. Page
Room 606 - Period 6 - With Ms. Pellegrino (while lab is in session)

1. Arrow up and to the right (use the parallelogram method)
2. 44m (use d = Vit + 1/2at^2, where a = 9.8, t = 3, Vi = 0)
3. 0 Degrees (180 degrees is minimum resultant, 0 degrees is maxiumum)
4. 100N (use change in velocity - 10m/s, over change in time - 1.5 s to find acc., then multiply by mass to find the force)
5. DE (this is where the slope of distance v. time is NOT constant, so velocity must be changing)
6. 40m (use Vf^2 = Vi^2 + 2ad)
7. .2h (use distance = average velocity * time)
8. 1 x 10^ -2 N (mass of insect x velocity of insect)
9. F (Force of friction only relies on Normal force, and coefficient of friction)
10. 10 m/s^2 (use v^2/r, NOT mv^2/r, because we are finding acceleration, not force)
11. 2.0s (Find the average acceleration (Vf + Vi)/2 , then use d = V*t to find t)
12. Arrow from the box, down and to the left, parallel to the plane (friction always opposes motion)
13. decrease (remember because F = Gm1m2/r^2, the distance r plays a greater factor)
14. copper (its coefficient is the smallest value).

Helpful Hints for the Exam Tomorrow

Forces:

• If there is a net force, that means an object is ACCELERATING.
• If there is NO net force (equilibrium), the object can still be moving, but there can't be a change in speed
• If something is moving at CONSTANT speed, then the sum of all the forces must be 0
• If something is moving at CONSTANT acceleration, then the NET FORCE must be constant.
• On an inclined plane, the parellel force is the weight * sin of angle.
• On an inclined plane, the perpendicular force is the weight * cos of angle
• When in doubt, use the equation Fnet = m * a
• As you make the angle of an incline greater, the parallel force increases (the object is more likely to slide down), and the perpendicular force decreases (the normal force decreases, also causing the object to slide).
• The direction of friction is always opposite the direction of motion.

Gravitational Force: F = (Gm1m2/r^2)

• If I double the mass of one object, I double the gravitational force between the two objects
• If I triple the distance between two objects, the force becomes 1/3^2 = 1/9 as big
• If I double mass, and distance, the force will still decrease because distance factors more than one mass

You should be comfortable drawing free body diagrams, identifying tension in a pulley system, and using the big 5 motion equations for horizontal and vertical motion.

And the Winner Is...

Guang Gui!

Depending on if you used 9.8 or 10, you may have gotten slightly different answers, but the solutions are in the image, so just click on it to bring it up in full size.

Remember, these types of questions WILL BE on the exam tomorrow so make sure you are prepared for them!

Solutions to Review Packet

Homework: Week of 11/5-11/9

Monday: TPS p47 109-112, Start Packet
Wednesday: Work on packet, study for Exam
Friday: EXAM 4, start studying for midterm!

5 points BONUS!

The first person to post the correct answers to the BACK side of that handout will receive 5 extra points on the exam Friday. You can post your answers as a comment on this post. You have until WEDNESDAY, which is when I will post the solutions.

Solutions to Exam 3 Questions

Hello All,

As you are enjoying your day off, a heads up: Exam 4 (Friday) WILL HAVE projectile motion, and regular motion questions on it!! Study the worksheet we went over today to make sure you can answer these questions.

<---------------------CLICK

Chapter 3 Review Questions - HW Solutions

1. b
2. d
3. a
4. c
5. a
6. e
7. e
8. d
9. d
10. a
11. e

Homework Oct 29 - Nov 2

Monday: TPS p38 65-70 PLUS exam review worksheet
Tuesday: TPS p47 113-120
Wednesday: TPS p50 121-123, 125; CP p52 12,13
Thursday: No Class
Friday: Finish Packet

Next Exam: Friday, Nov 9

Labs Due This Week

Inertia Lab: Due Monday Oct 29
Balloon Car Lab: Due Tuesday Oct 30

Solutions to Projectile Motion Sheet

A soccer ball is kicked....
t = 2.1s (use distance = vi*t + 1/2 at^2)
Vi = 16.7m/s (use distance = v * t)

A long jumper...
time = 1.1s (find the time it takes to get the peak using Vf = Vi + at, and double it)
horizontal distance = 11.66m
Vertical distance = Vit+1/2at^2 = 1.6m

A small mass...
Horizontal component of velocity: 40*cos35 = 32.8
Vertical component of velocity: 40*sin35 = 22.9
Time to peak = 2.3s (Vf = Vi + at)
Distance to peak = initial distance plus projectile = 46.7 m
Vertical Distance = 173m

Automobile accident...
time = .35s
Velocity = 13.1m/s

Solutions to Exam 3 Review Sheet

1. decrease
2. 10N
3. decreases
4. 1.6m/s^2
5. Arrow up and to the right
6. 10N 5N
7. 0 degrees
8. 5.0kg
9. 260N
10. 50N
11. 180 degrees
12. 11N
13. accelerating downward
14.
15. 2N
16. 13N
17. 10N
18. .5kg
19. 19.8N
20. 0
21. 0

Homework 10/22-10/26, EXAM WEDNESDAY

10/22 TPS p37 57-64
10/23 Study for exam
10/24 EXAM! (Newton's laws and mechanics equations)
10/25 No Class
10/25 No Class (PT Conferences)

Parent Teacher Conferences

Parent Teacher Conferences are this week!
Thursday: Nightime
Friday: Afternoon

Please make every effort to attend!

Homework - 10/15-10/19

10/15: TPS p34 43-49; CP p83 1-9
10/16: TPS p84 15, 15; CP p34 52-55
10/17: No Class
10/18: No Class
10/19: TPS p42 85-92; Read p35-37

Extra Credit Opportunity

Based on the results of the test Friday, it looks like some folks might want some extra credit. I will be offering the following:
Opportunity 1: You can go through each of the multiple choice questions, and provide 1-2 sentences for which answer is correct and why.
Opportunity 2: You can create your own mechanics worksheet, with at least 6 different questions:
One for each of the missing variables, plus one that is missing two variables.
These questions can be similar to the ones on the worksheet given in class, but must contain different numbers you select, such as changing the time from 2.4 s to 7 s (and they can't be the same exact problem as anything online either).

Topics on the exam

Scalar v. vector
Displacement v. distance, speed v. velocity
How to calculate displacement
The SLOPE of distance v. time is velocity/speed
The SLOPE of vecloity/speed v. time is acceleration
distance = rate * time
Vertical velocity changes, horizontal doesnt
Change in velocity/change in time = acceleration
As I increase the angle at which i launch something, the vertical component of the velocity goes up, the horizontal component goes down.
Centripetal acceleration increases with increased velocity, and decreases with increased radius, and always points IN
Remember/memorize the BIG FIVE equations!

Review Sheet Solutions

1. constant speed
2. twice as great
3. increase
4. 20 m/s^2
5. <------
6. 40m
7. 0 m/s^2
8. the same
9. 3.00 m/s
10. 10 m/s
11. three times as great
12. the same
13. 3.0m
14. 0.80s
15. 3.0m/s
16. The baseball and the balloon fall at the same rate
17. 45m

G-force

The amount of g-force the human body can handle actually depends on a couple of things:
1. How long the interaction is (how long the force is applied)
2. What direction the interaction is (horizontal or vertical)

Humans can withstain 100's of g's for example, for a mere second. However, over a sustained period of time (such as 20 g's for a minute) it can be deadly.

A typical person can sustain about 5g's in a vertical direction and about 17g in the horizontal direction.

The record for the most g force at an amusement park is 5.5g.

Fighter pilots can go between 6-9g, but may experience what is known as a "greyout" (temporary loss of vision, ability to speak, etc)

Formula One drivers typically experience 5g while breaking, 2g while accelerating, and 4-6 g when cornering.

Strongest g-forces survived by humans
Voluntarily: Colonel John Stapp in 1954 sustained 46.2 g in a rocket sled, while conducting research on the effects of human deceleration.
Involuntarily: Formula One racing car driver David Purley survived an estimated 179.8 g in 1977 when he decelerated from 173 km/h (108 mph) to 0 in a distance of 66 cm (26 inches) after his throttle got stuck wide open and he hit a wall.

Escape Velocity

The escape velocity on the surface of the earth is about 11.2 kilometers per second (which is about 6.96 mi/s)

Homework - Week of 10/8-10/12

10/8 No School
10/9 TPS p41 74-78; CP Read 119-128, do problems p84 21-23
10/10 Study for Exam
10/11 No Class
10/12 Exam Day

Homework - Week of 10/1-10/5

10/1 CP 9-14; TPS p28-29 11,15,18,23,28
10/2 TPS p29 29-33, 40-41
10/3 TPS p30 38-41, Read 39-41; CP p23 15-21
10/4 No Class
10/5 Finish Worksheet (yes, both sides); Read TPS p74-83

Homework - Week of 9/24-9/28

9/24 Read Chapter 2 TPS
9/25 TPS p27 1-3; CP p23 1-2
9/26 TPS p27 4-7; CP p23 3-8
9/27 No Class
9/28 TPS p28-29 #21

Homework - Week of 9/17-9/21

9/17 TPS p19 85-89
9/18 TPS p19 81-84
9/19 TPS p7 30-32

Homework - Week of 9/10-9/14

9/10: TPS p11 49-55
9/11: TPS p10 33-39, 42-44
9/12: TPS p3 1-15

Welcome

Hello all,

Welcome to Pellegrino's Physics Blog Page. This page will contain (not necessarily in this order)

• Homework Assignments
• Postings about Exams
• Easter Eggs about pop quizzes