ALL CIE PHYSICS DOUBTS HERE !!!

[astarmathsandphysics]

The compass points in the direction of the magnetic field, which is from south to north

[ashwinkandel]

Questions from Circular Motion:
Q1.
Explain why the toy falls off when the speed of the turntable is increased.

Q2.
A teacher swings a bucket of water, of total mass 5.4 kg, round in a vertical circle of diameter 1.8m. [3]
i.Calculate the minimum speed which the bucket must be swung at so that the water remains in the bucket at the top of the circle. [2]
ii. Assuming that the speed remains constant, what will be the force on the teacher's hand when the bucket is at the bottom of the circle? [1]

Q3.
In a training, military pilots are given various tests. One test puts them in a seat on the end of a large arm which is then spun round at high speed, as shown in the diagram.
i. Describe what the pilot will feel and relate this to the centripetal force.[3]
ii. at top speed the pilot will experience a centripetal force equivalent to six times his own weight (6 mg)
    a. Calculate the speed of pilot in this test. [3]
    b. Calculate the number of revolutions of the pilot per minute. [2]
iii. Suggest why it is necessary for pilots to be able to be able to withstand forces of this types [2]

Q4.
The diagram shows a centrifuge used to separate solid particles suspended in a liquid of lower density.
a.The container is spun at a rate of 540 revolutions per minute
i.Calculate the angular velocity of the container. [2]
ii. Calculate the centripetal force on the particle of mass 20mg at the end of the test tube. [2]
b. An alternative methods of separating the particles from the liquid is to allow them to settle to the bottom of a stationary container under gravity. By comparing the forces involved, explain why the centrifuge is more effective method of separating the mixture. [2]

The diagram for questions 1 , 3 and 4 are attached below.

[astarmathsandphysics]

1. The centripetal force is friction which cannot increases above a certain point (=mu R=mu mg where mu=coefficient of friction)
The centrifugal force is F=mv^2/r
When mv^2/r >mu mg the toy starts to slip

[astarmathsandphysics]

2,3,4 in attachmwnts

[Naruto123]

a) Calculate the displacement expressed as a fraction of the amplitude of a particle moving in simple harmonic motion with a speed equal to half of the maximum value .
b) Calculate the displacement at which the energy of the particle has equal amounts of kinetic and potential energies

thanku in advance

[astarmathsandphysics]

a)speed=wA*sin(wt) and max speed=wA so =wA*sin(wt)/wA =sin wt=1/2
x=Acos wt so x/A=cos wt=sqrt(1-sin^2 wt)=sqrt(1-(1/2)^2)=(sqrt(3))/2
b)1/2mv^2=1/2msin^2(wt)=1/2kx^2=1/2kcos^2 wt
tan^2 wt =k/m so tan wt =sqrt(k/m) and sec^2 wt=1/(cos^2 wt)=1+tan^2 wt =1+k/m so cos^2 wt=1/(1+k/m)
x=1/2k cos wt=1/2 k sqrt(1/(1+k/m))

[ashwinkandel]

Questions from the Chapter Charged Particles

1.
The diagram shows the path of an electron as it travels in air. The electron rotates clockwise around a uniform magnetic field into the plane of the paper, but the radius of the orbit decreases in size.
a i. Explain the origin of the force that causes the electron to spiral in this manner.[2]
ii. Explain why the radius of the ircle gradually decreases. [2]
b. At one point in the path, the speed of the electron is 1.0*10^7 m/s and the magnetic flux density is 0.25T.Calculate:
i.the force on an electron at this point due to the magnetic field.[2]
ii. the radius of the path at this point. [2]

2.
The diagram shows an arrangement to deflect protons from a source to a detector using a magnetic field. A uniform magnetic field exists only within the area shown. Protons move from the source to the detector in the plane of the paper.
a
i.Copy the diagram and sketch the path ofa proton from the source to the detector.
Draw an arrow at two points on the path to show teh direction of the force on the proton produced by the magnetic field. [3]
ii.State the direction of the magnetic field within the area shown.[1]
b.The speed of a proton as it enters the magnetic field is 4.0*10^6 m/s. The magnetic flux density is 0.25T. Calculate:
i. the magnitude of the force on the proton caused by the magnetic field. [1]
ii. the radius of curvature of the path of the proton in the magnetic field. [2]
c.Two changes to the magnetic field in the area shown are made. These changes allows an electron with the same speed as the proton to be deflected along the same path as the prton. State the two changes made. [2]

3.
The diagram shows an electron tube. Electrons emitted from the cathode accelerate towards the anode and then pass into a uniform electric field created by two oppositely charged parallel metal plates.
a i.Explain why the beam curves upward. [2]
ii. Explain how the pattern formed on the fluorescent screen shows that all the electrons have the same speed as they leave the anode.[2]
b. Write down an equation relating the speed of the electrons v to the potential difference V(ac) between the anode and the cathode.[1]
c. The deflection of the beam upward can be cancelled by applying a suitable uniform magneti field in the space between the parallel plates.
i.State the direction of magnetic field for this to happen. [1]
ii. Write down an equation relating the speed of the electrons, v , the electri field E that exists between the plates and the magnetic flux density B needed to make the electrons pass undeflected between the plates. [2]
iii. Calculate the value of B required, using the appratus shown in the diagram, given that the specific charge on an electron e/m is 1.76*10^11 C/kg [2]

4.Protons and helium nuclei from the Sun pass into the Earth's atmosphere above the poles, where the magnetic flux density is 6.0*10^-5 T. The particles are moving at a speed of 1.0*10^6 at right angles to the magnetic field in this region. The magnetic field can be assumed to be uniform.
a.Calculate the radius of the path of a proton as it passes avoce the Earth's pole.[3]
b.Draw a diagram to show the deflection caused by the magnetic field on a proton and on a helium nucleus which both have teh same initial velocity as they enter the magnetic field. State on the diagram the radius of the path of each particle.
Mass of helium nucles=6.8*10^-27kg;Charge on a helium nucleus = 3.2*10^-19 C [2]

5. In Milkan's oil  drop experiment, an oil drop of weight 1.5*10^-14 N is held stationary between plates 10 mm apart by a p.d between the plates of 470 V.
a.Draw a digram of the apparatus and explain why the oil drop remains stationary.[3]
b. i.Calculate the charge on the oil drop. [3]
ii. Explain what is meant by the quantanisation of charge. [3]
c. When the charge on the oil drop is changed, the p.d needed to keep the drop stationary also changes. Values of 940 V and 313 V are also obtained.
i.Describe how the charge on the oil drop can be changed while the drop remains between the plates.[1]
ii. Explain why only certain values of p.d are found in this experiment and predict another value of the p.d that mey be required when the charge on the oil drop is changed.[3]

The diagrams for questions 1,2 and 3 are attached below.

[astarmathsandphysics]

Will print this page to do in bed in morning

[astarmathsandphysics]

here

[Most UniQue™]

Can someone solve this ASAP. Got exam tomorrow. And please mention the formula you use.

Thanks in advance 

[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