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ALL CIE PHYSICS DOUBTS HERE !!!

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astarmathsandphysics:
R=sqrt(V/pi L)
%uncertainty in R is 1/2 (%uncertainty in V + %uncertainty in L)
because of the root
%=1/2 (0.5/15 +0.1/20) *100 =1.92%

ashwinkandel:
Questions from Gravitational Fields

Q1. Ganymede is teh largest of Jupiter's moons with a mass of 1.48 * 10^23 kg. It orbits Jupiter with an orbital radius of 1.07*10^6 km and it rotates on its own axis with a period of 7.15 days. It has been suggested that to monitor an unmanned landing craft on the surface of Ganymede a geostationary satellite should be placed in orbit around Ganymede.
a. Calculate the orbital radius of the proposed geostationary satellite.
b. Suggest a difficulty that might be encountered in achieving a geostationary orbit for this moon.

Q2.The planet Mars has a mass of 6.4 * 10^23 kg and a diameter of 6790 km.
a
i.Calculate the acceleration due to gravity at the planet's surface.[2]
ii. Calculate the gravitational potential at the surface of the planet. [2]
b.
A rocket is to return some samples of Martian material to Earth. Write down how much energy each kilogram of matter must be given to escape completely from Mar's Gravitational Field. [1]
c. Use your answer to b to show that the minimum speed that the rocket must reach to escape from teh gravitational field is 5000 m/s.
d. Suggest why it has been proposed that for a successful mission to Mars that the craft that takes the astronauts to Mars will be assembled at the space station and launched from there, rather than from the Earth's Surface [2]

Q3.
a. Explain what is meant by gravitational potential at a point. [2]
b. The diagram shows the potential near a planet of mass M and radius R.
On a copy of diagram, draw similar curves.
i. for a planet of same radius but of mass 2M- label this i. [2]
ii. for a planet of same mass but of radius 2R- label this ii. [2]
c. Use the graph to explain from which of the three planets it would require the least energy to escape [2]
d. Venus has a diameter of 12100 km and a mass of 4.87*10^24 kg.
Calculate the energy needed to lift one kilogram from the surface of Venus to a space station in orbit 900 km from the surface. [4]

Q4.
a. Explain what is meant by the gravitational field strength at a point. [2]
The diagram shows the dwarf planet, Pluto, and its moon. These can be considdered to be a double planetary system orbiting each other about their joint centre of mass.
b. Calculate teh gravitational pull on Charon due to Pluto. [3]
c. Use your result to b to calculate Charon's orbital period. [3]
d. Explain why Pluto's orbital period must be the same as Charton's [1]

Q5.
a. Determine the gravitational field strength at a height equal to 2R above the Earth's surface, where R is teh radius of the Earth. [1]
b. A satellite is put into an orbit at this height. State the centripetal acceleration of the satellite. [1]
c. Calculate the speed at which the satellite must travel to remain in this orbit. [2]
d
i. The diagram shows the orbital path of the satellite. Frictional forces mean that the satellite gradually slows down.
Copy the diagram and show on your copy the resulting path of the satellite. [1]
ii. Suggest and explain why there is not a continuous bombardment of old satellites colliding with the Earth.[2]

Figure are attached below[Gravitation Field>> q no. 3,4 and 5

ashwinkandel:
Questions from Chapter Coulomb's Law

Q1.
a. Define electric field strength. [2]
b. Two charged conducting spheres each of radius 1.0 cm are placed with their centres 10 cm apart, as shown in the diagram.
Sphere A carries a charge of +2*10^-9
The graph shows how the electric field strength between the two spheres varies with distance x.
i. Calculate the field produced by sphere A at the 5.0 cm mark.[2]
ii. Use your result to b i. to calculate the charge on sphere B. [3]
c.
i. Sphere B is now removed. Calculate the potential at the surface of sphere A. [2]
ii. Suggest and explain how the potential at the surface of sphere A would compare before and after sphere B was removed. [2]

Q2.
An alpha particle emitted in the radioactive decay of radium has an energt of 8.0*10^-13 J
a
i. Calculate the potential difference thata an alpha particle, initially at rest, would have to be accelerated through to gain this energy. [2]
ii. Calculate the speed of the alpha particle at this energy. [3]
b. The diagram shows the path of the alpha particle of this energt as it approaches a gold nucleus.
i. State the speed of the alpha particle at its point of closest approach to the gold nucleus. [1]
ii. Write down the kinetic energy of the alpha particle at this point. [1]
iii. Write down the potential energy of the alpha particle at this point.[1]
c. Use your answer to b iii. to show that the alpha particle will reach a distance of 4.5*10^-14 m from the centre of the gold nucleus. [1]
d. Suggest and explain what this information telles us about the gold nucleus. [2]
(Mass of an alpha particle= 6.65*10^-27 kg, charge on an alpha particle=+2e, charge on an gold nucleus= +79e)

Q3.
a.Define electric potential at a point. [2]
b. The graph shows the potential well near a hydrogen nucleus.
The first electron orbital can be considered to be a circle of diamter 1.04*10^-10 m.
i. Determine the potential at a point on this orbital. [2]
ii. Calculate the energy required to ionise the atom. [2]
c. Use the graph to estimate the electric field strength at a distance of 1.0 * 10^-10 m from the cetnre of the nucleus. [2]

4.The diagram shows a conducting sphere of radius 0.80 cm carrying a charge of +6.0*10^-8 C resting on a balance.
a. Calculate the electric field at the surface of the sphere. [2]
b.A identical sphere carrying a charge of -4.5*10^-8 C held so that its centre is 5.0 cm vertically above the centre of the first sphere.
i. Calculate the electric force between the two spheres.[2]
ii. Calculate the new reading on the balance. [1]
c. The second sphere is moved vertically downwards through 1.5 cm. Calculat the work done against the electric field, in moving the sphere. [3]

astarmathsandphysics:
Will do these in bed in morning

astarmathsandphysics:
Will do the other batch later

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