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Physicshelpline

. August 2017

Electromagnetic Induction: Wire on rails

Q- A rod of length L caused to move at a constant speed v along horizontal conducting rails. The magnetic field B is not constant, but is supplied by a long wire parallel to the conducting rails. This wire is a distance a from the rail and has a current i.  If L = 3.18 cm, v = 4.61 m/s, a = 10.8 mm…

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Simple Harmonic Motion

Q- A block is suspended by a vertical spring of constant 1800 N/m and makes 5.5 oscillations per second.

(a) Find the mass of the block.

(b) What is elongations in the spring if the block is at rest in equilibrium?

(c) If the block is pulled down by 2.5 cm from equilibrium position and released, …

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Gravitation

Q- Using mass of earth, distance between sun and earth and gravitation constant as given in your text, calculate mass of sun.

Solution:

 

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Ray Optics: Refraction Through Prism

Q- A beam of white light is incident on a glass prism at an angle of θ = 370 with the normal to the surface. The emergent angle for red light is φr = 750 and for violet light is φv = 790.

(a) If the angle of the prism is A = 450, find the refractive index of the glass for red and violet light.

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Rotational Motion: Angular Momentum

Q- A disk of mass M = 400 grams and radius R = 30 cm is free to rotate about its horizontal axis. A lump of clay of mass m = 100 grams falls from height h = 2m and sticks to the disk at the farthest point from the center. Find the angular velocity of the disk after collision.

Solution:

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Magnetic Effects: Force on a Charged Particle

Q- A charged particle with initial velocity v0 = 3 × 106 m/s in the positive x-direction enters a region of depth d1 = 1.1 m that has a uniform magnetic field B = 0.011 T in the positive z-direction (out of the page). The magnetic field is zero elsewhere. The particle leaves the magnetic field regi…

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Thermodynamics

Q - Refrigerant R22 enters a well-insulated compressor at 3.5 bar, -50C and exits at 14 bar. Determine the work input in kJ/kg if the outlet temperature 750C. (γ = Cp/Cv for R22 is 1.562 at -50C and 1.348 at 750C)

Solution:

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Wave Optics: Interference, Thin Films

Q- A very thin oil film (n = 1.25) floats on water (n=1.33). What is the thinnest film that produces a strong reflection for green light with a wavelength 500 nm? 

Solution:

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Waves

Q- Earthquakes are essentially sound waves traveling through the earth. They are called seismic waves. Because the earth is solid, it can support both longitudinal and transverse seismic waves. These travel at different speeds. The speed of longitudinal waves, called P waves, is 8000 m/s. Transverse…

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Electrostatics: Coulomb's Law

Q- Three charges are fixed in place as shown. The squares in the grid have sides of length s = 0.24 m. The magnitude of q is 3 µC while the magnitude of Q is 4.5 µC. What is the magnitude of the net force on q due to the other two charges?

Solution:

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Rotational Motion

Q- A ball is rolling without sliding up an incline with a velocity of 7 m/s. What will be its velocity when it reaches a vertical height h = 2 m above its initial position? 

Solution:

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Magnetic Effects: Force on a loop

Q- At t=0, a rectangular coil of resistance R = 2 ohms and dimensions w = 3 cm and L = 8 cm enters a region of constant magnetic field B = 1.6 T, directed into the screen as shown. The length of the region containing the magnetic field is LB = 15 cm. The coil is observed to move at constant velocity…

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Simple Harmonic Motion

Q- A particle M executes simple harmonic motion along x axis. The reference particle for this SHM moves on a circular path of radius R = 40 cm with a constant speed of 80 cm/s.

(a) Find the angular frequency, frequency and the time period for this SHM.

(b) If at t = 0, the reference particle makes…

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Gravitation: Potential Energy

Q- A body is projected vertically with a velocity of 6 km/s. Find the maximum height reached by projectile.

Solution:

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Electrostatics: Field

Q- Two charges q = -2 µC and Q = +4µC are placed at a distance d = 12 cm from each other. Find position of a point along the line joining the charges where the electric field is zero. 

Solution:

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Circular Motion: Banking of Road

Q- A car travels around a flat curved road with constant speed.

(a) Draw Free body diagram for the car.

(b) What is direction of net force acting on the car?

(c) Is there a maximum speed to negotiate the curve? If so find an expression for it.

(d) If the road is banked, derived an expression for…

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