Physics Questions and Answers October 14, 2022

What is the kinetic energy of the electrons as they leave the cathode in joules?

Determine the force of friction acting on a block sliding on a horizontal plane (10 marks)

Find the moment of inertia of a thin circular disk with mass m and radius r about its center (10 marks)

(Take g=10ms) Find the kinetic energy of the following: (a) a runner of mass 50 kg running at 6 ms (b) a hovercraft of mass 105 kg travelling at 25 ms (c) an electron of mass 910-28 g, speed 2x10 ms (d) a car of mass 1300 kg travelling at 60 kph.

(i) A gas at a temperature of 27C and pressure of 740 mmHg has a volume of 60 cm3. Calculate the number of moles of the gas present. (3 Marks) (ii) What happens to the number of moles of gas if the volume is doubled? (2 Marks)

(i) An ideal gas is compressed from an initial volume of 200 cm3 to a final volume of 80 cm3 at a constant temperature. Find the initial pressure of the gas. (3 Marks) (ii) How does the initial pressure compare to the final pressure? (2 Marks)

(i) State Boyles law. (2 Marks) (ii) A gas having 150cm3 volume has pressure 120cmHg. If the volume is increased to 30cm3 . Find the final pressure of the gas. (3 Marks)

iii. Determine the time taken to reduce the objects from a distance of 1m to 0.2m from the axis of rotation (10 marks)

Nasimiyu stands at the centre of a rotating platform that has frictionless bearings. She has a 2kg object in each hand, held 1m from the axis of rotation of the system. The system is initially rotating at 10rpm. Determine i. The angular velocity of the system in radius per second after the objects are brought to a distance of 0.2m from the axis of

Determine the displacement of a particle moving in one dimension with constant acceleration (10 marks)

Derive an expression for the velocity of a projectile at the highest point of its trajectory (10 marks)

Suppose that a car is moving with a velocity of 20 m/s and experiences a constant acceleration of 2 m/s^2 for 5 seconds. Calculate: a) The velocity of the car after 5 seconds. b) The displacement of the car after 5 seconds.

b) (i) Give the three equations of motion. (3 Marks) (ii) a bicycle moves with a constant acceleration of 4m/s2 . At time t = 0 seconds the bicycle is at distance x = 10m and travelling with a velocity of 5m/s2 . Calculate: a) The position of the bicycle at time t= 3 seconds. (3 Marks) b) Bicycles velocity at time t = 3 seconds. (2 Marks) c) State

l) (i) A sample of gas has a volume of 70 cm3, a pressure of 500 mmHg, and a temperature of 25C. If the volume of the gas is increased by 50% and the pressure is decreased by 50%, what will be the final temperature of the gas? (3 Marks) (ii) How does the temperature change with both pressure and volume changes? (2 Marks)

k) (i) A sample of gas has a pressure of 400 mmHg and a temperature of 20C. If the pressure of the gas is decreased by 50% and the volume remains constant, what will be the final temperature of the gas? (3 Marks) (ii) How does the temperature change with the pressure? (2 Marks)

(i) A gas has a volume of 90 cm3 and a pressure of 720 mmHg at a temperature of 20C. Calculate the final pressure of the gas if the volume is increased by 50% and the temperature remains constant. (3 Marks) (ii) How does the pressure change with the volume? (2 Marks)

A 8 kg object is thrown upwards with an initial velocity of 10 m/s from a height of 20 meters. Calculate the kinetic energy of the object at its maximum height.

A 2 kg object is thrown upwards with an initial velocity of 10 m/s and experiences a constant acceleration of -9.8 m/s^2 due to gravity. Calculate the height of the object after 3 seconds.

A 5 kg object is thrown upwards with an initial velocity of 20 m/s and experiences a constant acceleration of -9.8 m/s^2 due to gravity. Calculate the time taken by the object to reach its maximum height.

A 10 kg object is thrown downwards with an initial velocity of 20 m/s from a height of 50 meters. Calculate the velocity of the object just before it hits the ground.

A 4 kg object is thrown vertically downwards with an initial velocity of 10 m/s. Calculate the kinetic energy of the object when it hits the ground.

e) State three factors affecting pressure in liquids. (3 Marks) f) If density of a liquid is 20 g/cm3 , height is 4cm and gravitational field strength is 10N/kg, calculate pressure of the liquid.

Suppose a W created in a bubble chamber lives for 5.001025 s. What distance does it move in this time if it is traveling at 0.900c Since this distance is too short to make a track, the presence of the W must be inferred from its decay products. Note that the time is longer than the given Wlifetime, which can be due to the statistical nature of

Calculate the force exerted by the liquid on a 1 m2 area at the bottom of the container.

Given that pressure of a liquid is 1000 pa, density of the liquid as 20 g/cm3 , calculate the height of the liquid. (take g = 10N|kg)

What is the final temperature of the gas if the initial pressure is 100 cmHg, the initial volume is 200 cm3, the final pressure is 200 cmHg, and the final volume is 400 cm3?

Gas in a cylinder having initial volume 200 cm3 and final volume 400 cm3 has a pressure of 100 cmHg. Calculate the final pressure.

A thermally insulated vessel contains 150 g of water at 0 0 C. Then the air from the vessel is pumped out adiabatically. A fraction of water turns into ice and the rest evaporates at 0 0 C itself. The mass of evaporated water will be close to (Latent heat of vaporization of water = 2.10 10 6 J/kg and latent heat of fusion of water = 3.36 10 5

Given the volume of the liquid as 50 cm^3, density of the liquid as 20 g/cm3, and acceleration due to gravity (g) as 10 N/kg, calculate the weight of the liquid.

V has one of the longest known radioactive halflives. In a difficult experiment, a researcher found that the activity of 1.00 kg of 50 V is 1.75 Bq. What is the halflife in years

On the optical bench, arrange the optical bench lamp with the metal F object in place over the opening. You will place a lens at various distances from the F object and record information about the images. (Top View) Bench lamp F object 54 cm 36 cm 27 cm 12 cm 5,1 Lens Screen or Head Location For each case, first you will attempt to locate the

Verify equations rnn2Z aB using the approach stated in the text. that is, equate the coulomb and centripetal forces and then insert an expression for velocity from the condition for angular momentum quantization.

What is the reading of the ammeter (d) What is the reading of the voltmeter 22.5 V 20 V 14 V ov E Fig 1 b 2.4k 5.6k

Drude theory of AC transport. The Drude theory can be extended to study the response of a metal to a timedependent electric field E(t) Eweit. From this we can understand why a metal is shiny, and also find a surprising result in the ultraviolet. (a) Using the ansatz Pav Pweit, solve the Drude equation for pw. Hence obtain the current j(t) je it

A passenger in an automobile observes that raindrops make an angle of 30 with the horizontal as the auto travels forward with a speed of 60 km/h. Compute the terminal (constant) velocity v r of the rain if it is assumed to fall vertically.

A passenger in an automobile observes that raindrops make an angle of 30 with the horizontal as the auto travels forward with a speed of 60 kmh. Compute the terminal (constant) velocity vr of the rain if it is assumed to fall vertically.

The ship travels at a constant speed of v s = 20 m/s and the wind is blowing at a speed of v w = 10 m/s, as shown. Determine the magnitude and direction of the horizontal component of velocity of the smoke coming from the smoke stack as it appears to a passenger on the ship.

The ship travels at a constant speed of vs 20 ms and the wind is blowing at a speed of vw 10 ms, as shown. Determine the magnitude and direction of the horizontal component of velocity of the smoke coming from the smoke stack as it appears to a passenger on the ship.

A capacitor made of two parallel plates, each of area A and separation W is charged by an external d.c.-source. Show that during charging, the displacement current inside the capacitor is the same as the current charging the capacitor.

The magnetic susceptibility X of magnesium at 300 K is 1.2 10 5 . At what temperature will its magnetic susceptibility become 1-44 10 5 ?

A 200 F parallel plate capacitor having plate separation of 5 mm is charged by a 100 V dc source. It remains connected to the source. Using an insulated handle, the distance between the plates is doubled and a dielectric slab of thickness 5 mm and dielectric constant 10 is introduced between the plates. Explain with reason, how the (i)

Draw a plot of a-particle scattering by a thin foil of gold to show the variation of the number of the scattered particles with scattering angle. Describe briefly how the large angle scattering explains the existence of the nucleus inside the atom, Explain with the help of impact parameter picture, how Rutherford scattering serves a powerful way

Prove that the magnetic moment of the electron revolving around a nucleus in an orbit of radius r with orbital speed v is equal to evr/2. Hence using Bohrs postulate of quantization of angular momentum, deduce the expression for the magnetic moment of hydrogen atom in the ground state.

In the 3span beam shown in the Figure 2, the support at C settles by 15 mm. Using the method of moment distribution method, a) Calculate joint moments (10 marks) b) Draw the bending moment diagram (10 marks) c) Calculate the supports vertical reactions (10 marks) and d) Draw the shear force diagram (5 marks). Hint For the calculation of Fixed End

A swimming pool is filled with 2 m of water at 10?C (i.e. ?w = 9803 N/m3). Its bottom is square and measures 4 m on a side. Two opposite sides are vertical; one end is at 45? and the other makes an angle of 60? with the horizontal. Calculate the magnitude of force due to water on: (a) the bottom, (b) a vertical side, (c) the 45? end, (d) the 60?

One end of a thin wire of negligible mass is attached to the ceiling and the other is attached to a solid silver ball. The tension in the wire is 175 N. a. Find the radius of the ball. (10pts) b. If the ball were immersed in water what would be its weight (10pts)

For the beam and loading shown in figure, determine (a) The equation of the elastic curve (eq. of deflection) for the cantilever beam, for AB and BC. (two equations) (b) The deflection at B. (c) The deflection at the free end, and (d) The slope at the free end. Assume that El is constant for the beam. A L2 B W L2 C X

Using any known method of circuit analysis determine the unknown voltages and the currents in all the branches in the circuit below 01 5V 8 (1) 1.25 A U2 U3 20 12 40 UA 15V

Use the BiotSavart Law to determine the magnitude and direction of the magnetic field at the common center (P) of two concentric wire arcs of radii, b0.6 m and a 0.3 m that are connected by straight segments. The two wires that form the arcs carry unequal currents I 10 A and I 15 A. 2.6 x 106 T, into page P R R

Direct electric current of 25 mA is maintained in a circular loop of radius 10 cm and consisting of 100 turns. An external magnetic field, 0.5 T, is directed at an angle of 60 with the plane of the loop. (a) Calculate the magnitude of the torque exerted on the loop by the magnetic field. 1.96 x 102N.m (b) What is the magnitude of the magnetic

Containers A and B have equal volumes. The mass of the liquid in B is 6589.0 times the mass of helium gas in container A. If you know that the density of helium is 0.180 kg/m 3 , what is the density of liquid B?

A student performed the experiment of determining the focal length of a concave mirror by the u-v method using an optical bench of length 1.5 m. The focal length of the mirror used is 24 cm. The maximum error in the location of the image can be 0.2 cm. The 5 sets of (u, v) values recorded by the student (in cm) are : (42, 56), (48, 48), (60, 40),

A biconvex lens of focal length 15 cm is in front of a plane mirror. The distance between the lens and the mirror is 10 cm. A small object is kept at a distance of 30 cm from the lens. The final image is (a) virtual and at a distance of 16 cm from the mirror (b) real and at a distance of 16 cm from the mirror (c) virtual and at a distance of 20 cm

In a labbased course, a common activity is to measure the linear kinematics of motion in the 100 meter dash. This activity involves 10 students acting as timers. Each student is placed at 10meter intervals along the length of the course. At the starting line, Vo 0, and to 0. As the race begins, all students start a stopwatch (all are assumed to

Work out the matrix representations of the Sx, Sy, and S operators. As well as S and S... Given that sms) s(s1)sms), show that the matrix form of S S S.

The truss structure shown in Figure 4 is subjected to a vertical force P 1 at point 3. Let a 1. Each bar has the same EA 1. Calculate the nodal displacements and elemental internal forces by the displacement method. 4 a1 P1 Figure 4 2 3 a1

The cylinder, with the piston still locked in place, is now immersed in a mixture of ice and water and allowed to come to thermal equilibrium with the mixture. The piston is then moved inward very slowly, in such a way that the gas is always in thermal equilibrium with the icewater mixture. We will refer to this slow compression of the gas as

The approximate number of photons in a femtosecond (1015 s) pulse of 600 nanometers wavelength light from a 10kilowatt peakpower dye laser is A. 103 B. 107 C. 101 D. 105 E. 1018

The ground state of the helium atom is a spin A. singlet B. doublet C. triplet D. quartet E. quintuplet

The wave function for identical fermions is antisymmetric under particle interchange. Which of the following is a consequence of this property A. Pauli exclusion principle B. Bohr correspondence principle C. Heisenberg uncertainty principle D. BoseEinstein condensation E. Fermis golden rule

What is the maximum altitude that the aeroplane can reach, given its velocity, weight, and wing surface area?

An aeroplane weighing 39.24 kN is flying in a horizontal direction at 360km/hr. The plane spans 15m and has a wing surface area of 35m2. If the drag coefficient CD=0.03 and density of air is 1.22kg/m3 . Determine (i) Coefficient of lift (3 marks) (ii) Power required to drive the plane (3 marks)

120g of a solid initially at 245 kelvin was carefully dropped into water in a calorimeter at 280 kelvin. If the final constant temperature of the water and solid was 254kelvin and the water is 750g, determine the specific heat capacity of the solid. Assume the heat absorbed by the calorimeter to be negligible. Take the specific heat capacity of

A fluid with a flow rate of 0.0007 litres per second is passing through a soil sample that has a height of 9 cm and a cross-sectional area of 50 cm^2. The head of the fluid is maintained at a constant value of 6 cm. Calculate the permeability coefficient of the soil sample.

Water at a rate of 0.0006 litre/sec, is flowing through a sandy specimen of 8 cm height and 45cm 2 cross-sectional area under a constant head of 7cm. Determine the coefficient of permeability

A liquid of viscosity 0.09Ns/m2 is filled between two horizontal plates 10mm apart. If the upper plate is moving at 1m/s with respect to the lower plate which is stationary and the pressure difference between the ends of the flow channel 60m apart is 60kN/m2 . Determine (i) The velocity distribution across a x- section of the flow channel (2

A convex lens is put 10 cm from a light source and it makes a sharp image on a screen, kept 10 cm from the lens. Now a glass block (refractive index 1.5) of 1.5 cm thickness is placed in contact with the light source. To get the sharp image again, the screen is shifted by a distance d. Then d is (a) 0.55 cm towards the lens (b) 0 (c) 1.1 cm away

The eye can be regarded as a single refracting surface. The radius of curvature of this surface is equal to that of the cornea (7.8 mm). This surface separates two media of refractive indices 1 and 1.34. Calculate the distance from the refracting surface at which a parallel beam of light will come to focus (a) 4.0 cm (b) 1 cm (c) 3.1 cm (d) 2 cm

In an interference experiment the ratio of amplitudes of coherent waves is (a 1 /a 2 ) = ?. The ratio of maximum and minimum intensities of fringes will be (a) 4 (b) 9 (c) 2 (d) 18

A concave mirror for face viewing has a focal length of 0.4 m. The distance at which you hold the mirror from your face in order to see your image upright with a magnification of 5 is (a) 0.16 m (b) 1.60 m (c) 0.32 m (d) 0.24 m

The value of the numerical aperture of the objective lens of a microscope is 1.25. If the light of wavelength 5000 is used, the minimum separation between two points, to be seen as distinct, will be (a) 0.48 m (b) 0.12 m (c) 0.38 m (d) 0.24 m

An observer looks at a distant tree of height 10 m with a telescope of the magnifying power of 20. To the observer, the tree appears (a)10 times taller (b)10 times nearer (c) 20 times taller (d) 20 times nearer

You are asked to design a shaving mirror assuming that a person keeps it 10 cm from his face and views the magnified image of the face at the closest comfortable distance of 25 cm. The radius of curvature of the mirror would then be (a) 30 cm (b) 24 cm (c) 60 cm (d) 24 cm

A block is at the top of a frictionless ramp that is 2.0 m long and 0.10 m high at one end. Use the figure and coordinate system shown in the lab manual (and in textbook example 3.4). The block starts from rest and takes 2.5 seconds to travel 1.8 meters down the ramp. a. What is the value of sin b. What is the magnitude of the acceleration in the

Draw the influence lines for (a) the vertical reaction at B, and (b) the moment at E. Assume the supports at B and D are rollers. There is a short link at C. Solve this problem using the basic method of Sec. 61. 612. Solve Prob. 611 using the MllerBreslau principle. AXX E 10 ft10 10 ft IB ft 15 ft Probs.61112 C 15 ft ID

The following stress distribution has been determined for a machine component. Is equilibrium satisfied in the absence of body forces T 6xy34 T 0 0 3xy54 4x4y6 3x3y 3y

Assume Earth is a spherical blackbody of radius 6,371 km. It absorbs heat from the Sun at a rate given by the solar constant equal to 1379 Wm2. Furthermore, assume Earth has an equilibrium temperature of 278.9 K and is immersed in space, which has a temperature of 50 K. Assume the Earth radiates heat back into space equally in all directions. At

The radiated power P of an accelerating (nonrelativistic) charge depends on the speed of light c., magnetic permeability of free space ., acceleration of the charge a and the charge q by the formula PHqam 11,(a) 4 pts. Given that the units of power P are Watts kgms and . kg mC, where C is Coulombs and s is seconds, what are the integer exponents

1) In the circuit at right the resistors are r192 R402 R302 R62 R202 Ks160 The current , is 2.0 A. Battery 8, is a real battery which has an internal resistance r and an unknown emf , while battery B, is an ideal battery with , 2.0 V. B 352 ww 102252 Rs Ra 4 B a) Draw and name all currents on the diagram. Use Kirchhoffs laws to write equations.

A uniform disk of radius R and mass 5 kg is pivoted such that it rotates freely about its central axis as shown in the diagram. A string wrapped around the disk is pulled with a force of 20 N. The disk accelerates rad at 25. The moment of inertia for a disk is laisk 5 kg b. Find the radius of the disk. Axis of rotation goes intoout of page a. If

Figure 1 shows a schematic diagram of a system. Force F is applied to the spring on top of the beam. Displacement x may also be applied on top of the beam. Assume mass of springs are negligible. Assume the mass of the beam is negligible. Assume no bending occurs in the beam. Note Force F and displacement x are not applied simultaneously. K F X 1

Consider a mass m which is attached to two identical springs on a flat frictionless surface. The figure shows an overhead view of the setup. The mass only moves along the zaxis. When r 0 the springs are at their natural lengths of L. Analyse the systems potential energy to determine whether or not the masss small amplitude oscillations can be

A solid semicylinder of radius r rests under the action of gravity on a hard fixed cylindrical surface of radius R as shown. If rolled slightly to the left or the right and released, the semicylinder will rock from side to side (assume no slipping). (a) From first principles, show that the location of the centroid of mass of the solid semi

According to Quantum Mechanics, the translational energy levels e, of a single particle of mass m 100 kg in a cubic box of volume VL1 cm are given by a) b) o) d) Tn with n nnn and n,,,.n0. 2ml Explain the fundamental role played by this model in statistical physics and show that the energy states of this particle can be conveniently represented

Is there a time t 0 when the probability of measuring spin up in the xdirection is equal to zero If so, determine a time when this occurs and explain your reasoning. If not, explain why not.

Heat conduction in a spherical nuclear fuel element. Consider a spherical nuclear fuel ele ment as shown in Fig. 10B.3. It consists of a sphere of fissionable material with radius R, surrounded by a spherical shell of aluminum cladding with outer radius R. Inside the fuel element, fission fragments are produced that have very high kinetic

The resistivity of a piece of silver at room temperature 1.6 108 m. The effective number of conduction electrons is 0.9 per atom and the Fermi energy is 5.5 eV. Estimate the mean free path of the conduction electrons. Calculate the electronic relaxation time and the electronic drift velocity in a field of 100 Vm1. The density of silver is 1.05 104

What is y(gamma) if v0.250c (b) If v 0.500c

If the Sun suddenly turned off, we would not know it until its light stopped coming. How long would that be, given that the Sun is 1.50 x 10 m away

You note that your prescription for new eyeglasses is 4.50 D. What will their focal length be

A Virtual image of 4cm is formed using a Complex lens of focal Lenth 20cm. If size of object is Im determine position of F20 Obled

What is the force responsible for the upward motion of a rope climber?

Obtain the values for the mesh currents i, and is in the circuit above.

Certain heavy industrial equipment uses AC power that has a peak voltage of 679 V. What is the rms voltage

What force is exerted on the water in an MHD drive utilizing a 25.0cmdiameter tube, if 100A current is passed across the tube that is perpendicular to a 2.00T magnetic field (The relatively small size of this force indicates the need for very large currents and magnetic fields to make practical MHD drives.)

What is the maximum force on an aluminum rod with a 0.100C charge that you pass between the poles of a 1.50T permanent magnet at a speed of 5.00 ms In what direction is the force

Calculate the emf of a dry cell for which a potentiometer is balanced when R 1.200 92, while an alkaline standard cell with an emf of 1.600 V requires R1.24792 to balance the potentiometer.

(a) What is the resistance of ten 2759 resistors connected in series (b) In parallel

An alpha particle (a helium nucleus, containing 2 protons and 2 neutrons) starts out with kinetic energy of 9.9 MeV (9.9x105 eV), and heads in the x direction straight toward a gold nucleus (containing 79 protons and 118 neutrons). The particles are Initially far apart, and the gold nucleus Is Initially at rest. Answer the following questions

An electron of 1 MeV kinetic energy and a positron of 1 MeV kinetic energy have a head on collision (same velocity but in the opposite direction). After the annihilation, the electron and the positron disappear, and a pair of gammy rays is created. (a) Should this pair of gammy rays have the same kinetic energy always Why Yes, because energy is

Express the 9.8kN force F as a vector in terms of the unit vectors i, j, and k. Determine the scalar projection of F onto the xaxis and onto the line OA. 31 F9.8 kN 53 A 30

If you want a characteristic what value of selfinductance RL time constant of 1.00 s, and you have a 50092 resistor, is needed