A common argument from contrarians of the human impact on global warming about the increase in CO2 levels of the atmosphere is that the increase in carbon dioxide by humans is only a small percentage of the total sources of emitted CO2. In other words, the argument is that humans cannot be the cause of the increase in warming of the climate since the added emissions is a small percentage of what is added to the atmosphere from natural forces like volcanoes. In your response, address the following: What are the natural carbon sources and sinks? How does the emission of carbon by humans affect this balance? Why is this argument short-sighted of the feedback mechanisms built into our ecosystem? How would you explain to this contrarian that his argument is missing a larger picture?
In: Physics
1) a) Derive a relationship between the electric field (E) and electric potential (V) knowing that V is defined as the energy per unit test charge.
b) Based on the above derivation, state an alternate acceptable unit for (E).
In: Physics
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3. |
Planet Z has diameter 1.8 × 107 m. On the planet's surface, the acceleration due to gravity is 19.5 m/s2. What is the mass of the planet? Note: The constant of universal gravity (G) equals 6.674 × 10-11 N ⋅ m2/kg2. |
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As shown in the diagram, two massless wires connect a rotating pole to a sphere.The sphere has mass 7.2 kg and it revolves in a horizontal circle at constant speed. At this particular speed the tension is the same in both wires. What is the speed of the ball? |
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Two people, each of mass 85 kg, are positioned 8.0 m away from each other. What is the magnitude of the gravitational attraction between them? Note: The constant of universal gravity (G) equals 6.674 × 10-11 N ⋅ m2/kg2. |
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A racecar experiences a centripetal acceleration of 36.0 m/s2 as it travels at a constant speed of 27.0 m/s along a circular arc. What is the radius of the circle? |
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A particle travels in a circle of radius 76 cm and completes one revolution in 4.5 s. What is the centripetal acceleration of the particle? |
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Satellite B revolves around Earth 4 times a day. What is the radius of its orbit, measured from Earth's center? Assume that Earth generates the only significant gravitation attraction on the satellite. Note: The mass of Earth is 5.98 × 1024 kg, and the constant of universal gravity (G) equals 6.674 × 10-11 N ⋅ m2/kg2. |
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An astronaut has weight W on Earth. The astronaut travels to a planet that has a mass 4 times greater than Earth's mass, and its radius is 2 times greater than Earth's radius. What is the astronaut's weight on the planet? |
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The gravitational acceleration at the surface of planet X is 11.6 m/s2, and the radius of the planet is 66,500 km. An astronaut is hovering at height h above the planet's surface, and she notices her weight is the same as it is on Earth. What is h? |
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Earth's radius is 6380 km. An object is dropped from a height 622 km above Earth's surface. What is its initial acceleration in terms of g, the acceleration constant due to gravity at Earth's surface? |
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At the top of a looped section of roller coaster track, the car and rider are completely upside down. What information is necessary to calculate the minimum speed of the car that will prevent a rider from falling out of it? Assume the rider is not strapped into the car. |
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In: Physics
An electron is accelerated through potential difference of 350V. Electron enters magnetic field and moves in the circle with the radius of 7.5cm.
a) What is the magnitude of the field?
b) What is the angular speed of electron?
c) What is the period of revolution of the electron?
In: Physics
A car accelerates from rest to 60 mph in 4.8 seconds. It then continues at constant velocity for 10 seconds. Determine the distance in the first part and in the second part. Also, what is the car's acceleration in the first part? In the 2nd part? What is it's velocity at the end of the first part( which is also maximum velocity)? (show all work)
distance1=
distance 2=
accel1=
accel2=
velocity max=
In: Physics
a.) Find the pressure difference on an airplane
wing where air flows over the upper surface with a speed of 120 m/s
and along the bottom surface with a speed of 90 m/s.
_____ Pa
b.) If the area of the wing is 25 m2,
what is the net upward force exerted on the wing?
____ N
(You may assume the density of air is fixed at 1.29
kg/m3 in this problem. Also, you may neglect the
thickness of the wing-- though could you incorporate this too, if
it was given?)
The answer is NOT a) 3.4x10^4 and b) 8.5 x 10^5. These were both incorrect.
In: Physics
1)When the three blocks below are released from rest, they accelerate with a magnitude of 0.500m/s2. Block 1 has mass M, block 2 has 2M, and block 3 has 2M. What is the coefficient of kinetic friction
2)A block of mass m is held stationary on a ramp by the frictional force on it from the ramp. A force ?,directed up the ramp, is then applied to the block and gradually increased in magnitude from zero. During the increase, what happens to the direction and magnitude of the frictional force on the block?
3)The figure below shows an initially stationary block of mass m = 2.00 kg on a floor. A force of magnitude 10.0 N is then applied at upward angle θ = 20°. What is the magnitude of the acceleration of the block across the floor if (a) μs = 0.600 and μk = 0.500 and (b) μs = 0.400 and μk = 0.300?
In: Physics
A 15μF capacitor has an initial charge of 50μC. It is discharged
through an 8000Ω resistor. Find:
a) the current at 17ms;
mA
b) the charge at 17ms;
μC
c) the power loss in the resistor at 17ms.
mW
d) How long does it take for the energy in the capacitor to drop to
20% of its initial value?
ms
In: Physics
John is listening to a horn. When the horn and John are both at rest, the frequency of the horn is 300 Hz. If he hears a pitch of 330 Hz, there are clearly several possibilities. State which of the possibilities are correct.
1. Both can be moving and have the same speed
2. John is moving towards the horn at rest
3. The distance between John and the horn is increasing with time
4. Both can be moving in opposite directions
5. Both can be moving and have different speeds
6. John and the horn are both moving in the same direction but John is behind and moving faster than the horn
In: Physics
A molecule of DNA (deoxyribonucleic acid) is 2.31
In: Physics
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A small metal bead, labeled A, has a charge of 29 nC . It is touched to metal bead B, initially neutral, so that the two beads share the 29 nC charge, but not necessarily equally. When the two beads are then placed 5.0 cm apart, the force between them is 5.2×10−4 N . Assume that A has a greater charge. |
Part A What is the charge qA and qB on the beads? Express your answer in nanocoulombs. |
In: Physics
A spherical steel ball bearing has a diameter of 2.540 cm at 29.00°C. (Assume the coefficient of linear expansion for steel is 11 ✕ 10−6 (°C)−1. )
(a) What is its diameter when its temperature is raised to 96.0°C? (Give your answer to at least four significant figures.) cm
(b) What temperature change is required to increase its volume by 0.800%?
In: Physics
A carpenter's square has the shape of an L as shown in the figure below. Locate its center of gravity. (Take
(x, y) = (0, 0)
at the intersection of d1 and d4. Assume
d1 = 20.0 cm,
d2 = 5.00 cm,
d3 = 5.00 cm,
and
d4 = 13.0 cm.
)
In: Physics
If you were shown three different interference patterns (double slit, single slit, and diffraction grating), how could you tell the difference between them?
Newton thought that light wasn't a wave because he couldn't see diffraction or interference. Imagine you are transported back in time to convince him otherwise. Write a 1-2 paragraph explanation for Newton explaining why he does not see these features despite the wave nature of light.
In: Physics
In a lab where the Helmholtz coil equation combined with energy conservation is used to determine the charge per mass ratio of the electron what are some random and systematic errors, how can they be minimized, and what does a vector diagram of the experiment look like? Can you explain to me how an experiment of this sort would look?
In: Physics