Science+Physics+9

=Design Challenge= For the design challenge, Peggy, Emily, and I have decided to work on a Mindstorms robot, which we have used to build the Alpha Rex. Currently, it is equipped with the ability to walk, touch, hear, react to light, and talk. We have been successful in having the robot walk, yet we have not tested the other actions. The motors used in the robot convert electrical energy to mechanical energy, allowing the robot to move. =Page 192 Multiple Choice Questions= 1. B 2. C 3. C 4. C 5. A 6. A 7. D 8. A 9. B 10. A =Experiment(s)= How will the Lego Mindstorms robot react to different types of light, such as infrared, ultraviolet, visible, etc? Which colors can the Lego Mindstorms robot detect? When the robot is being guided by a wire, does its speed change? =Page 108 Review Questions= 12. Yes a machine can multiply input and output force, but not input energy. Energy can never be created or destroyed. 13. Distance is diminished by dividing by four. 14. The machine's efficiency would be 100%. 15. No, because for all machines, a small percentage of the input energy is converted into another type of energy that is not useful. Even for a lever, 2% of the input energy is converted into output energy and wasted. In all machines, when objects rub together, energy is wasted as heat. Therefore, it is impossible to have the perfect machine. =Page 108 Review Questions= 6. If the car was lifted twice as high, then there would be twice as much potential energy. 7. The car that is twice as massive has twice as much potential energy. 8. 4 joules of potential energy; 8 joules of potential energy 9. It has 16 times as much potential energy, because the speed in proportion to the amount of kinetic energy is squared. 10. The work the breaks of a car uses would be the same. This is because friction does not depend on speed. However, the stopping distance would be nine times as far. = =

=Page 108 Review Questions= 1. An example of this would be if a person pushes down on a table using force, but it does not move in any direction. 2. They both require the same amount of work. 3. The 50 kg sack would require twice as much power. If the lighter sack was moved its distance in half the time, then the power required would be the same for both. 4. A body having energy has the capability to do work. 5. The two main forms of mechanical energy are kinetic energy and potential energy. =Chapter 10= 1. For permanent magnets, how and why do the magnetic domains stay lined up? 2. In an electric motor, how is the current reversed at each half revolution? 3. In an electric motor, how does the current reverse itself at a pace fast enough to keep up with the rotating loop? 4. Why do charged particles at rest not experience a magnetic force? 5. What is torque, mentioned in Figure 10.3? =Mysterious Circuit= On the science table. =Page 173= 1. All the light bulbs should be equally bright. 2. All the currents should be the same. 3. The bulbs from greatest to least are C, B, and A. 4. a) Part C, part B, part A b) The voltage is the same =Page 173 Think and Solve= 2. Amperes=volts/ohms; 8 omega=12 volts/1.5 amperes 3. 6 V battery=4 V + 2 V, the voltage does not change or disappear, so the two should add up to 6 V. 4. resistance=voltage/current; 120 V/20A=6 Omega 5. power=current x voltage; 6W=.05A x 12 V =Circuit Diagram= Here's the picture with labels of the circuit Peggy and I did in class. The diagram is in my notebook (: == Figure 1 shows two batteries making a closed circuit and lighting a light bulb. Each major section of the circuit is labeled. Figure 2 is the diagram of the same circuit shown in the above picture.

=Science Chapter 9 Questions= 7. A good conductor of electricity is also a good conductor of heat because these types of materials have a greater jostling of atoms within the conductor, producing more heat. 8. The brightness of the light also increases. 9. An ampere is a measurement of the rate of electrical flow but a voltage measures electrical pressure. They are not the same thing. 10. Number 5 11. The current flow is the same, whether it is going in or out. This is because a circuit flows in a loop so the amount should be the same. 12. The rest of the energy is converted into heat energy. 19. The brightest light bulb is light bulb C, which also means that it draws the most current. If light bulb A is unscrewed, then both A and B will turn off, but if C is unscrewed, then only C will be off. =Science Chapter 9 Questions= 1. If you fell from a bridge and grabbed a high-voltage power-line, why would no shock be felt, because wouldn't the rest of your body's voltage be different from your hand? 2. What is the difference between the live and neutral parts of a plug? 3. How does the electric signal travel at the speed of light if the speed of electrons is less than 1 cm per second? 4. Why do more pathways create less resistance of a current? 5. What is an alternating current used for?

=Science Car Crash Questions= =Science report= I could not save this as a pdf file because the formatting made the tables overlap with each other.

[[file:sci reportrevise.docx]]
=Page 73 Multiple Choice #1-10= 1. d 2. b 3. b 4. c 5. c 6. a 7. a 8. c 9. c 10. b =**Page 72 #10-12, 16-18**= 10. The heavier cart would only move half as fast as the lighter cart, due to having more mass. 11. 200 N, because the create is not accelerating. Yes, the force of friction is equal and oppositely directed to the 200 N push. The reaction force would be the crate pushing against your hand. 12. The impact force is the same on both vehicles because the action and reaction forces are equal and opposite. The sportscar experiences the greater acceleration though, because the mass of the vehicle is much smaller, yet the same force is being applied to both vehicles. 16. Another arrow would be draw going upwards at the same length as the arrow going downards. The conventional name for this vector is velocity. (Drawings in notebook) 17. The vectors should have a zero resultant because the stone is not moving and is therefore in equilibrium. (Drawings in notebook) 18. The vecor going upwards because a larger force is needed to keep the stone accelerating upwards. (Drawings in notebook) =**How the Forces Apply to my Car**=

Many forces are acting on my car as it moves and stays still. The force of gravity pushes the car down and keeps it from floating away. The support exerted from the floor cancels out the gravity coming downwards. When the car is moving, the wheels are pushing up against the floor. Due to every action having an equal and opposit reaction, the floor is also pushing on the tires, causing the car to move. Drag is also pushing up against the car as it moves forward. The first law of motion, that every object is in a state of rest or uniform speed unless a nonzero force is exerted on it can be seen in that the car stays still unless a force acts upon it, which in this case is the motor powering the wheels. For the second law of motion--acceleration~net force/mass, when the mass of the car was increased the time it had to carry weights, the acceleration was much less than when the weights were not present on the car. The third law of motion which states that whenever one object exerts a force on a second object, the second object exerts an equal and opposite force on the first. This can be seen on the wheels of the car. They push on the floor, in turn causing the floor to push on the wheels, allowing the car to move. The car accelerates due to engine moving the wheels, changing its speed. Forces also cause acceleration, meaning that the wheels of the toy car are pushing against the ground, allowing it to move. Mass also determines acceleration. Therefore, I tried to use a smaller mass when building my car, allowing it to gain a greater speed. Friction also applied to my car, which is a force that acts opposite to the direction of motion. The wheels allow my car to feel less friction, due to the floor and the wheels not being pressed together as much. =**Page 55 Multiple Choice #1-10**= 1. b 2. a 3. b 4. b 5. d 6. c 7. a 8. a 9. d 10. b =**Page 55 #2, 3, 5, 8, 9, 13, and 14**= 2. It hurts because there is a larger force acting upon your hand, the mass of the heavy load. Your hand has a smaller mass than the heavy load, and therefore has a smaller less force. Since every action has an equal and opposite reaction, when only your hand hits the wall, a smaller reaction is felt. However, when both the heavy load and your hand hit the wall, a larger force is given to the wall, causing a larger reaction on your hand. The law that is most applicable is the second law, which is netforce=massxacceleration. 3. No, because the mass is measurement of the amount of matter within a certain object. Therefore, no matter what shape it is in, the mass is still the same. No, because the amount of matter is still the same as well as the force of gravity acting on the object. Therefore, the weight should still remain the same. Yes, the volume did chance because it is compacted to take up a smaller amount of space. The matter within the object is simply squished together. 5. The force of friction is 1 N, because the book is sliding at a constant velocity. This means that the object is in equilibrium and the net force is 0. The forces should cancel out, so the force of friction is 0 N. 8. They accelerate at the same speed. This is because according to Newton's second law, acceleration=netforce/mass. Due to one basketball being filled with rocks, the force acted on that basketball is greater. However, there is also more mass within that basketball than the lighter basketball. This cancels out to be the same acceleration. 9. Since the parachutist is no longer gaining speed, the two forces are equal meaning the parachutist is at equilibrium. 13. The terminal speed before opening the parachute is much faster than after. This is because by increasing the surface area through the parachute, the terminal speed decreases. The greater surface area allows air drag to build up quicklier. 14. Before terminal velocity, the gravitational force is much greater on the falling body than air drag, accelerating the object. However, after it reaches terminal velocity, the two forces are equal, so the object does not accelerate. =**Page 36 Multiple Choice #1-10**= 1. a 2. b 3. c 4. b 5. a 6. c 7. a 8. a 9. d 10. b =**Page 36 #14, 15, and 16**=

14. The write scale reads 450 N. This is because in order for the scaffold to stay stable, the ropes must be able to support the weight of the two people and the scaffold, equaling 850 N. As 400 N is already supported, 450 N must be the force the second rope pulls upward for the scafford to stay in place. If there was too much force, meaning a quanitity over 450 N, then the ropes would pull the people and the scaffold up. If there was too little force, then the ropes would break, causing the people to fall.

15. The reading on her scale should equal her weight, because the force needed to keep her dangling on the rope instead of falling is the same number as her weight. The tension acting on her upwards should cancel out with her weight, making the two quantities equal.

16. The rope doesn't break when Harry ties both ends of the rope to his chair because each rope is supporting half of his weight. Therefore, one individual rope supports 250 N, which is 50 N below the breaking point. Harry ended up taking an early vacation after injuring himself when the rope snapped. When both ropes were tied to his chair, rather than just one rope, his weight was divided among the two ropes, creating less tension for one individual rope. Since he tied the flagpole to one end, the rope ended up having to support both weights. This probably led to the rope sliding through the wheel, making Harry fall lower and the flagpole move upward. The tension on the rope then snapped, causing Harry to fall. =**Page 35 # 2, 4, 6, 7, 9, 13, and 19**= 2. The race-car cannot be at a constant velocity of 100 km/h because it made a curve. Velocity comprises of speed and direction. Therefore, a change in direction would be a change in velocity.

4. For the bear, if I ran in a zig-zag pattern it would be harder for the bear to follow me because of its larger mass. This is because of inertia. Inertia is a tendency for objects to stay in the state of rest or the state of motion it currently is in. Due to the bear's larger mass, it has a greater inertia than I would, making it more difficult for the bear to change velocity and follow.

6. Newton's first law of motion is: A force was applied to the toy wagon to allow it to move forward. However, a force was not acted upon the ball sitting in the wagon. Therefore, the ball's inertia would allow the ball to have a tendency to stay at rest, explaining why the ball rolls over to the back of the wagon when the wagon moves.
 * Every object continues in a state of rest or of uniform speed in a straight line unless acted on by a nonzero net force.

7. When a bus slows, the people inside lurch forward due to the people's inertia. Inertia makes our body want to stay in motion while we are moving with bus, even when it slows down, causing people to lurch forward when the bus slows. The same reason applies for when the bus speeds up. When the bus changes speeds, inertia makes our bodies want to stay in the same speed, which in the case of when the bus speeds up, causes our bodies to lean back. This corresponds to Newton's first law of motion.

9. If the engine is not running, eventually, the friction acting upon the car will eventually slow down and stop. If the friction was not present, then the car will keep moving in the same velocity without the need of an engine to run it.

13. The scafford weighs 150 N because in order for the scaffold to be still, the upward force must be equal to the downard pull. The upword force is at 400 N and the person weighs 250 N. Therefore, the scaffold must weigh 150 N so that the two forces will balance out.

19. When the coin is tossed straight upward, it will land on the spot below where it was tossed. This is because the coin's inertia keeps it going at the same speed of the train, even when it is tossed in midair. If the train suddently slows, the coin should land in front of where it was thrown from due to the coin moving at the speed of the train before it slowed down. If the train turns, then the coin would land to the right or left of where it was thrown from, due to the coin not changing its velocity like the train. ** =**Lab Science 9 Excel Graphs**=

[|sci graphs tracey 2a.xlsx]