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. July 2018

Newton's Laws: Friction and Inclined Plane

Q- A body of mass 80 kg is to be pushed upward along an inclined plane making angle 300 with horizontal. The coefficient of friction between the body and the plane is 0.2. Find the smallest force required if applied

(a) Horizontally

(b) Along the incline

Solution:

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Linear Charge Density

(On request- Harsh)

Q- (a) Linear charge density of a half ring varies with θ as λ = λ0 cos θ. Find total charge on the ring.

    (b) If the linear charge density of a wire of length L depends on the distance x from its one end as λ=λ0x/L, find total charge of the wire.

Solution:

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Photo Electric Effect

Q-The maximum kinetic energy of photoelectrons is 2.8 eV. When the wavelength of the light is increased by 50%, the maximum energy decreases to 1.3 eV. What are the following quantities?

(a) The work function of the cathode

(b) The initial wavelength

Solution:

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Momentum and Impluse

(a) What is the impulse needed to stop a 20 kg bowling ball moving at 5 m/s?

(b) A 2000 kg car accidentally drops from a crane and crashes at 30 m/s to the ground below and comes to an abrupt halt. What is the momentum at impact?

(c) A railroad diesel engine weighs two times as much as a freight c…

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Electromagnetic Induction

Q- A square conducting loop with sides length a = 0.5 m is placed in a magnetic field. The magnetic field varies in time according to the graph. If the area vector of the coil is in the same direction as magnetic field, what is the magnitude of the induced EMF in the coil at t = 25 s, 35 s and 60 s?…

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