Chapter+4

=Chapter 4: Thrills and Chil = Physics Homework & Textbook

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What Do You See? pg. 292
girl pushing boy around sharp turns acts like a roller coaster

What Do You Think? pg. 292
The roller coasters that give the most screams are the ones that are in the dark, have sharp turns, flip upside down, when you're about to fall, gforce, and go really fast

Investigate pg. 292
PART A:

PART B: 1a. -chair could fall -chair could go in the wrong direction -toes could get run over -slam into a wall -head could jerk forward or backwards - need to go at a resonable speed - have common sense 3a. Julia laughed and screamed while she experienced sharp turns, long fast distances, and spins. The overall ride was rated a 5. 4a. Yes the velocity was responsible for the reaction. Julia reacted more when she was changing velocity 5a. - 6a. 7a. 7b.

Physics Talk
Scalar: a quantity that has magnitude (size/amount), but no direction Displacement: the difference in position between a final position and an initial position; it depends only on the endpoints, not the path; displacement is a vector quantity, it has magnitude (size) and direction Vector: a quantity that has both magnitude (size/amount) and direction Speed: distance traveled divided by the time elapsed; speed is a scalar quantity, it has no direction Velocity: displacement divided by the time elapsed; velocity is a vector quantity, it has magnitude (size) and direction acceleration: the change in velocity divided by the time elapsed; acceleration is a vector quantity, it has magnitude(size) and direction

In the diagram the curve shows the actual path that the object took, but the straight line shows the distance (displacement) it traveled

Example: if you walk from your house to school, and then back to your house and you traveled 5 meters your displacement would be zero because your initial and final positions are the same.

Average velocity = displacement/ time elapsed v=∆d/∆t acceleration= change in velocity/time elapsed a=∆v/∆t

**Checking Up Questions**
1. Distance is the full direction you traveled and displacement is the distanced you traveled from point A to B 2. zero 3. Speed deals with the distance traveled and velocity deals with the displacement 4. acceleration= change in velocity/time elapsed (a=∆v/∆t

Physics to Go Page 358
4/26/11 1&2.

3a. la paz 3b. 40,000/24= 1,666.67 km/h 3c. You don't get a big thrill because you're traveling at a constant speed 4. 12/3=4 m/s^2 5a. speed 5b. velocity 5c. acceleration 5d.velocity (3ms up), displacement 5e. displacement 6. 10/2= 5m/s^2 7. 5/5= 1m/s

Physics Talk
gravitational potential energy: the energy a body possesses as a result of its position in a gravitational field. Kinetic energy: energy an object possesses because of its speed. Joule: the SI unit all forms of energy equivalent unite for the joule are kg(m)^2/ s^2 of N(m). Mechanical energy: the sum of kinetic energy and potential energy.

Checking up
1. increases the speed 2. Heights affect GPE; mass does not 3. increases with speed and mass 4. turns to kinetic energy 5. 30,000 J

Investigate
gate || Velocity at bottom || KE (bottom) || % Difference ||
 * Trial || Mass || Height || GPE(top) || Width of Ball || Time through
 * 1 || .226kg || .063m || .140J || .038m || .0369s || 1.02981 || .113J || -15 ||
 * 2 || .226kg || .147m || .325J || .038m || .0253s || 1.502 || .254J || -20.9 ||
 * 3 || .226kg || .229m || .507J || .038m || .0201s || 1.89 || .404J || -20.3 ||
 * 4 || .226kg || .312m || .691J || .038m || .0172s || 2.209 || .551J || -20.1 ||
 * 5 || .226kg || .397m || .879J || .038m || .0154s || 2.468 || .688J || -21.6 ||



Physics To Go
1. It's the same 2. 3. GPE: 60,000 KE: 50,000 both= 11,000 GPE: 0 KE: 0 both = 0 GPE: 30,000 KE:750 both = 30,750 GPE: 15,000 KE: 150,000 both= 165,000

5. GPE: 75,000 KE: 0 both = 75,000 GPE: 0 KE: 75,000 both= 75,000 GPE: 37500 KE: 37,500 both= 7,5000 GPE: 15,000 K: 55,000 both= 75,000

7. GPE= MGH= (.2kg)(10 m/s^2)(.75m)=14.7J 8. masses cancel out 9a. B 9b. C & F 9c.D

What Do You See? pg. 372
-Girl writing different types of energy on the board - Measuring the energy in the spring toy - Pop up toy shooting up -Person setting up another pop up toy - Person measuring the width of the pop up toy

What Do You Think? pg. 372
In order for a roller coaster to get to its highest point it needs a spring, pulley system, chain system It takes more for a roller coaster to lift it up if there is a bunch of people. It is heavier so more work needs to be done

Investigate pg. 372
Objective: determine the launch velocity of a vertical ball launcher Theory: The launcher gives the ball KE which is converted into GPE. Assuming energy conservation: KEi=GPEf The velocity of the ball can also be measured using a phtotogate. If the photogate method produces (nearly) the same result then this would validate our method (if:KEi=GPEf)


 * Trial || Mass of Ball (kg) || height (m) || V using energy (m/s) || width of ball (m) || time through gate (s) || V using photogate (m/s) || % difference ||
 * 1 || 1 ball || 1.00 ||  || .038 || .0074 ||   ||   ||
 * 2 || 1 ball + N || .81 ||  || .04 || .0092 ||   ||   ||
 * 3 || 1 ball + 2N || .66 ||  || .042 || .011 ||   ||   ||
 * 4 || 1 ball + 3N || .53 ||  || .044 || .013 ||   ||   ||
 * 5 || 1 ball + 4N ||  ||   || .046 ||   ||   ||   ||

Physics Talk pg. 374
-a spring that is difficult to compress or stretch will have a large spring constant (k). That spring will "pack" more SPE for an identical compression than a spring that is easy to compress -the total energy of a spring toy that can jump into the air is the sum of the SPE, GPE, and KE. Once the spring is compressed, the sum of these three energies must remain constant -GPE+KE+SPE= constant -mgh+1/2mv^2+1/2kx^2=constant
 * -spring potential energy**: the energy stored in a spring due to its compression or stretch
 * -calculating SPE**: SPE=(1/2)kx^2
 * -k** is the spring constant
 * -x** is the amount of stretch or compression of the spring

Checking Up pg. 377
1. After a "pop up" toy leaps off the table the spring potential energy is 2. 2 J 3. 2 J 4. spring constant and compression

Physics To Go pg. 380
1.


 * position above table (m) || SPE || KE || GPE || SPE + KE + GPE ||
 * at rest (0m) ||  ||   ||   ||   ||
 * just popping up (0m) ||  ||   ||   ||   ||
 * peak height .6 m ||  ||   ||   ||   ||
 * spring partially up 0 m ||  ||   ||   ||   ||
 * picked position .4 m ||  ||   ||   ||   ||

0.0.25 0.0.25 0.0.25.25

last row:

2. 1+2 -SPE SPE- - - - - - - - Ke - - GPE - - -- -- -- -___-__

__3__ __- - - -__ __- - - -__ __- - - -__ __GPE ET__ KE GPE __-____- -____-__ SPE

__-____-

3.

4. SPE KE GPE KE 5. all the energy for the roller coaster is from the first hill, 6. loses energy through friction 7.300x10x15= 45,000 J of energy 8a. (1/2)mv^2=58,800 8b. should be the same 8c. 58800/400(10) 15 meters 9. it increases, ke decreases, and there is no spe 10. 11a. KE=1/2mv^2 =1/2(.02)(2.7)^2 =.0729J GPE=mgh = (.0)(9.8)(.4) = .0784J No they are not the same, the KE is higher than the GPE 11b. .13m 11c. 12a. 12b.PICTURE 13.

What Do You See?
Its not fun on the moon It is fun on mars Mars is getting more speed

What Do You Think?
Gravity's direction is towards earth People in Australia are not upside down because they are being pulled towards the earth

Physics Talk
Gravitational field: the gravitational influence in the space around a massive object inverse-square relationship: relationship between the magnitude of a gravitational force and the distance from the mass. This also describes how electrostatic forces depend on the distance from an electrical charge Newton's Law of Universal Gravitation: all bodies with mass attract all other bodies with mass; the force is proportional to the product of the two masses and get stronger as either mass gets larger; the force decreases as the square of the distance between the two bodies increases Gravity: The force of attraction between two bodies due to their masses Fg is the force between the bodies r is the distance between their centers m1 and m2 are the masses of the bodies G is a universal constant equal to 6.67 x10^-11N x m^2/kg^2

Checking Up pg.387
1. towards the center of the earth 2. when the field lines are closer together 3. It would become weaker and become 1/9th 4. 10 5. an oval

Physics To Go
1. 4 times smaller 2a. 1/4 2b. 9x less 2c. 16x less 3. this question does not make sense 4. 9.8 both ways 5a. the water, because of tidal buldges 5b. The moons gravitational pull affects the tide of the water where the moon revolves around the earth 5c. Whereever the moon is closest to on the earth, the water there is at high tide and same with the opposite side of the earth while the sides next to the sides that the moon is facing has no tide (earth moves to moon while moon is moving towards the earth) 6a. They wouldn't swim in circles 6b. yes 7a. 1/4 7b. 7c. 16x 7d. 4x 8a. doubled 8b. tripled 8c. quadrupled 8d. halved 9a. 4x 9b. 9x 9c. 16 9d. 1/4 10. doubled, 9x, 6x

What Do You See? pg. 392
Left Picture: older, weighing item on old scale, simple technology Right Picture: new technology, equations on the board, chemicals in the background, weighing the same item but in a highly advanced scale, suspension scale

Physics Talk pg. 396- 399
where **F** is the force exerted by the spring
 * Hooke's Law**: the restoring force exerted by a spring is directly proportional to the distance of stretch or compression of the spring
 * Equation**: force exerted by the spring = -spring constant * spring stretch (compression)
 * X** is the stretch (compression) of the spring
 * K** is the spring constant

The equation for the relationship between mass and weight on Earth is **weight = mg.** This equation is similar to Newton's second law **(force=ma)**. Where **"a" equals 9.8m/s^2**
 * Weight:** the force exerted on a mass as a result of gravity; the weight force on an object due to Earth is downward, in the vertical direction

When an object is moved from Earth to the Moon, its mass stays the same, but its weight changes due to the change in the gravitational field strengths of Earth (g=9.8N/kg) and the moon (g=1.6 N/kg)

Checking Up pg. 399
1. five times 2. the spring constant is an indication of how easy or difficult it is to stretch or compress a spring 3. a 1kg mass on Earth has a weight of 9.8 N 4. When you step on a scale the spring compresses just enough to provide un upward force equal to your weight

Investigate
PART A: 1a. 16 ounces 1b. yes, it measures the mass of something 1c. the force exerted on a mass of a body by a gravitational field 2a. They are seventy kilograms different, the football player is a lot heavier 3a. 64 N and 176 N 4a. 5 4b. 1 5a. 6000

PART B: 2a. paper springs back slightly 3a. paper expands 4a. no it stays closer to how much it is stretched 6a.
 * Mass || Weight || Stretch ||  ||
 * 20lb ||  || 11cm ||   ||

7a. 7c. We predicted 60 grams would stretch 6 cm 8a. The actual stretch was 5.5
 * mass g || weight || stretch of spring cm ||  ||
 * 20 || 1.96 || 1.5 ||  ||
 * 50 || 4.9 || 4 ||  ||
 * 100 || 9.8 || 8 ||  ||
 * 70 || 6.86 || 5.5 ||  ||
 * 120 || 11.76 || 10 ||  ||
 * 150 || 15.42 || 12.5 ||  ||

2a. 3a. Weight Unknown Stretch 3.0cm Weight by assumption: 40g
 * Part C:**
 * Weight(g) || Stretch(cm) ||
 * 20 || 0.5 ||
 * 50 || 1.0 ||
 * 100 || 2. ||

Physics To Go pg 402
1a. 980N 1b.98N 1c. 588 N 2a. 32.5 N 2b. 4000 N 2c. 200 N 3c. slope: .15 3d. spring constant 4. 12/3=4 5. The spring's stretch determines the force 6. 15N/cm 7. 3/2= 1.5N/cm 8. The stretch or compression determines the weight

weight = mass * 9.8 m/s^2 maa is in kg weight is in newtons 1 Kg = 2.2 lbs ← conversion factor my weight in lbs: 135lbs my mass in kg (convert from lbs) = 61 kg my weight in Newtons (calculate using Fw=mg) = **1.00 LB IS 4.45 NEWTONS ("exact")**

What Do You See?
- two people in elevators - one person is bigger than the other -more force pushing down on the scale going on - fat guy is free falling, so there is no force exerted showing that the scale reads zero -there is more force on the small kid because he is accelerating upwards

What Do You Think?
Yes (to both questions) it does, because its like the picture we looked at in the beginning of the section when you are acceleration upwards you weight is less than usual and when you and speeding down a hill you are either in free fall or you weigh more than normal

MINI CHALLENGE: Name: Space Jam Theme: Outer Space Ride must include: vertical loops (min 360 degrees), horizontal loops (minimum 360 degrees), a camel hump (a 2nd hump after the initial hump), horizontal curves (minimum 90 degrees) -- at least one of each of these features You will eventually build a working model of your ride. The dimensions of your model is limited to a base of 50 cm x 100 cm and it may be up to 100 cm tall.

1a. 200g 2a&b. 3a. It gets smaller but at a constant speed its equal 4a. 5a. Yes, because gravity goes towards the earth 5b. Yes, because of the Fnet 5c. no 5d. Yes, they are the same 5e. done 6a. No net force is acting on it 1a. The scale reading gets larger 1b. You are looking at apparent mass 1c. 2a. Yes 2b. Yes 2c. no 2d. spring scale should be longer 3a. ok 4a. Your apparent weight would be greater in an elevator when you are going upwards 5a. The apparent weight would decrease as you go down 5b. apparent weight would decrease 6a. Weight doesn't change. 6c. Weight would be less 6d. Yes 7a. 8a. Accelerate both ways. Apparent weight changes on both. Roller coasters move in different direction
 * Part A**
 * || acceleration (up, down, zero) || scale reading (larger, smaller, equal to weight) ||
 * mass at rest || zero || equal ||
 * mass up at constant speed || zero || equal ||
 * mass accelerating upward || up || larger ||
 * mass at rest at top || zero || equal ||
 * mass moving down at constant speed || zero || equal ||
 * mass accelerating downward || down || smaller ||
 * Part B**

Physics Talk

Checking Up

What Do You See?
Sharp Turn Looks like they are going to fall off There is nothing holding the cart in the roller coaster is impossible to happen because the second hump is higher than the first the vertical slope is also impossible

What Do You Think?
You do not fall out of the roller coaster because of centripetal force is pulling towards the center, high speed that the roller coaster is traveling, and your seat belt

Physics Talk
All objects moving in circles or curves must have a force toward the center of the circle. All objects moving in circles are also accelerating. In a vertical loop, the centripetal force can be either the gravitational force, the normal force of the track on a roller coaster car, or a combination of the two; you need to add the forces as vectors. At the bottom of the circle, the normal force (red vector) points toward the center of the circle (upward) while the gravitational force (blue vector) points downward. The vector sum of these two forces must be towards the center of the circle. You can therefore conclude that the normal force is larger than the gravitational force. The normal force corresponds to your apparent weight, as it did in the investigation in the previous section. This is why you feel as if you weight more at the bottom of the loop of the roller coaster.
 * Normal Force**: The force acting perpendicular to the surface
 * Centripetal force:** any force directed toward the center the causes an object to follow a circular path at constant speeds
 * Centripetal Acceleration:** the acceleration directed toward the center of a circle experienced by an object traveling in a circular path at constant speed

Checking Up pg. 429
1. Centripetal force 2. Yes, there will be centripetal acceleration 3. The track and gravity 4. Normal force/ gravity 5. The mass, curve, and radius determines the amount of force that is needed

Investigate pg. 420
1a. It has forward motion. 1b. It has circular motion. 1c. The car will go off on a tangent. It will go forward. 1d. The car went forward. 2a. centripetal force 2b. Its going inward 4. picture 5a. yes 5b. The force is down. The force is towards the middle 5c. picture
 * Part A**

1a. The string gets tighter and he needs to apply more force 1b. The faster the stopper, the more force applied to the stopper 2a. You need to apply A LOT more force 2b. To compare force 2c. The more mass, the more force 3a. It requires more force and more motion of the fingers when its longer 3b. The number of stoppers and the speed 4a. It is much easier because gravity is working with you 4b. top 4c. After the slack, you feel the force again. When there is slack you feel nothing 5a. You need more force 5b. more force 5c. bigger change is more force and a smaller radius is less force 5d. make the track sturdier and make the cart more connected to the track 6a. large 6b. small 9a. yes 9b. yes 9c. yes 11a. Very large and the force from the speed 11b. If its going fast there is a higher force towards the center
 * Part B **

Physics To Go pg 433
1a. circle 1b. it would go off into a tangent 2a. centripetal force 2b. go in a straight line 3. because there would be more tension 4. easier cause the more force that goes down the more so the normal force goes up 5. Fnet= force m=mass v= velocity r= radius 6a. no 6b. yes 6c. a=28.28 m/s /2s a= 14.14 m/s^2 8. normal force, gravity, centripetal force and there is 2 of each 9. all the forces together cause centripetal force 10. at the top of the loop normal force: 3500 N because Fc=mg+fn 4000= 500 + 3500

bottom of the loop first space: 500 second space: 6500 slow moving: at the top: 300 at the bottom: 3300

11. At the top because all the forces are pressing down on you 12. centripetal force 13a. heavy 13b. light 13c. heavy 13d. heavy 13e. normal 14a. up 14b. down 14c. up 14d. up 14e. none 14f. sideways 14g. down

What Do You See? pg. 436
Kids are pulling and pushing the roller coaster to the top (doing work) once they get to the top of the hill they start going faster when they go down the hill two kids are in the car and one kid is holding on on the back

What Do You Think? pg. 436
it takes more force to pull a roller coaster up a steep hill You have to apply more force

Physics Talk pg 441
Work: the product of displacement and the force in the direction of the displacement; the energy transferred to an object Power: the work done divided by the time elapsed; the speed at which work is done and energy is transferred Watt: the SI unit for power; 1W = 1j/s

Checking Up
1. potential energy 2. from the kinetic energy at the bottom 3. less force to gradually lift it than to lift at a higher incline 4. brakes convert KE to thermal energy 5. j/s

Physics to Go
1a. the GPE at the bottom of the incline will have no GPE, but it will have x amount at the top 1b. ww=fd=mgh 1c. SPE=1/2kx^2 1d. 1/2kx^2 1e. GPE to KE to SPE 1f. when it hits the spring 2a. 0 because he is moving horizontally and not moving it up or down 2b. 60*.5= 30 nm 2c. 75*40= 2960 nm 2d. 500*.7= 350 nm 3. transferjkmn 4. the mass of the cart 5a. 10,000*20=200000 5b.200000/150=1333.3333

6.

Section 9: Force and Energy: Different Insights
What Do You See?

Roller Coaster Proposal
SourceURL:file://localhost/Users/carvalce/Desktop/space%20jam%20final.doc Space Jam is a roller coaster that will get your adrenaline pumping. It combines GPE and KE to give you an exhilarating experience you will remember for a lifetime. The large drop and extreme height of it provides the coaster with a lot of gravitational potential energy. As you travel down the initial drop you accelerate quickly due to the steep drop, resulting in gaining kinetic energy. Eventually most of the gravitational potential energy that you started with at the top of the roller coaster is converted to kinetic energy. This newly found kinetic energy gives you just the right amount of velocity to make a revolution around the vertical loop and to give the feeling of weightlessness. You now gained back some gravitational energy at the top of the loop that will again be converted to kinetic energy as you head towards the bottom of the loop. At the bottom of the loop your energy is almost all kinetic and little potential. At this point in the ride you feel pressed into your seat and feel as though you have suddenly gained a substantial amount of weight. This is due to Newton’s laws, because you are accelerating, you feel a force exerted on you. Now you enter the arguably most exciting part of the roller coaster, the horizontal loops. As travel through this section you will go around one and a half circles horizontally. This will exert a force on you that will push you outwards and back into your seat and again make you feel very heavy. Now you travel into the camelback, a portion of the track that will make you feel like you are going to fly out of your seat. This again will gain potential energy as you climb which will again be converted back to kinetic energy. This kinetic energy will get you to the conveyor belt that brings the ride back to the top. A certain amount of force is applied over a distance and time for the conveyor belt to reach the top, in other words power is used. Now you can enjoy Space Jam over and over again!
 * Proposal: Space Jam**


 * Scale Diagram:**






 * Free Body Diagrams:**




 * Safety Features**
 * 1) 1. Seat belt: We need a seatbelt that goes over your head and shoulders and locks in place. This seat belt is necessary for our roller coaster because of the intense, drop and vertical loops.
 * 2) 2. No Wheels: For our roller coaster we used a trough, like ones used in Olympics bobsledding, this object is design with sides to keep the cart in instead of attaching wheels.
 * 3) 3. Structure: the beams of the roller coaster are very sturdy and support the roller coaster track very efficiently to ensure that the track will never break
 * 4) 4. Check Ups: Every hour someone walks the track checking every part of the roller coaster to make sure bolts are screwed in tightly, tracks are in place, and nothing is out of the ordinary. There is also an initial test every morning where the roller coaster is tested three times before letting people ride it
 * 5) 5. Stopping: In order to stop the roller coaster safely we designed a efficient way to stop it by increasing the angle of the track and having it land into a conveyor belt that either ends the ride or brings you back to the top
 * 6) 6. Precautions: People with high blood pressure, [|heart disease] or heart condition, [|pregnancy] cannot ride this ride because of the dangerous health risks it may cause. This also applies to people who have been consuming alcohol or if you don't meet the height and weight requirements.

Section 10: