Archives

If earth suddenly stops rotating, then the weight of an object of mass m at equator will [ω is angular speed of earth and R is its radius ] :

a) decreases by mω2R b) increase by mω2R c) decrease by mmωR2 d) increase by mωR2 Answer: b)... View Article

An aeroplane of mass 3×10⁴ kg and a total wing area of 120 m² is in a level flight at the same height. The difference in pressure between the upper and lower surface of its wings in Kilo Pascal is( g = 10 ms⁻²)

a) 2.5 b) 5.0 c) 10 d) 12.5 Answer: a) 2.5 Solution: Pressure, Δp=F/A =mg/A =(3×104×10)/120 =2.5 x 103 = 2.5 kPa... View Article

The electric potential changes from 10 V to 30 V as one moves along x-axis from x = 0 to x = 2m . The magnitude of the electric field in the origin is

a) 10 V/m b) 20 V/m c) 5 V/m d) Both (a) and (b) Answer:a) 10 V/m Solution: E = (30 - 10)/(2-0)= 20/2 = 10 V/m... View Article

A battery of emf 2 V and internal resistance 0.5 Ω is connected across a resistance of 9.5 Ω. How many electrons cross through a cross-section of the resistance in 1 second?

Answer: 1.25 x 1018 Solution: Req = 0.5 + 9.5 = 10 Ω The current in the circuit is i = 2v/(10Ω) = 0.2 A Thus,... View Article

A proton moving with a constant velocity passes through a region of space without any change in its velocity. If E and B represent the electric and magnetic fields respectively. Then, this region of space may have

a) E = 0, B = 0 b) E = 0, B ≠ 0 c) E ≠ 0, B = 0 d) E ≠ 0, B ≠ 0 Answer: a, b, d Solution: a) If E... View Article

A rod AB slides on a V-shaped wire with speed v as shown, such that at any time OA=OB=l. The magnetic field in the region is perpendicular downwards and has strength B, the induced emf in the rod is

a) zero b) Bvl c) √3Bvl/2 d) Bvl/2 Answer: b) Bvl Solution: Given, OA=OB=l Since OA and OB are equal ∠OBA and ∠OAB are also equal ∠OBA... View Article

A block of mass m is placed at rest on an inclined plane of inclination θ to the horizontal. If the coefficient of friction between the block and the plane is μ, then the total force exerted by the inclined plane on the block is:

a) mg b) μmgcosθ c) mg sinθ d) μmgtanθ Answer: a) mg Solution: The total force exerted by block =mg,... View Article

A boy weighing 25 kg climbs up from the first floor at a height 3 m above the ground to the third floor at a height 9 m above the ground. What will be the increase in his gravitational potential energy? (Take g=10Nkg⁻¹)

a) 1500 J b) 0 J c) 150 J d) 2250 J Answer: a) 1500 J Solution: P.E=mgh In the first case that is in 3 m... View Article

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Archives

If earth suddenly stops rotating, then the weight of an object of mass m at equator will [ω is angular speed of earth and R is its radius ] :

An aeroplane of mass 3×10⁴ kg and a total wing area of 120 m² is in a level flight at the same height. The difference in pressure between the upper and lower surface of its wings in Kilo Pascal is( g = 10 ms⁻²)

The electric potential changes from 10 V to 30 V as one moves along x-axis from x = 0 to x = 2m . The magnitude of the electric field in the origin is

A battery of emf 2 V and internal resistance 0.5 Ω is connected across a resistance of 9.5 Ω. How many electrons cross through a cross-section of the resistance in 1 second?

A proton moving with a constant velocity passes through a region of space without any change in its velocity. If E and B represent the electric and magnetic fields respectively. Then, this region of space may have

A rod AB slides on a V-shaped wire with speed v as shown, such that at any time OA=OB=l. The magnetic field in the region is perpendicular downwards and has strength B, the induced emf in the rod is

A block of mass m is placed at rest on an inclined plane of inclination θ to the horizontal. If the coefficient of friction between the block and the plane is μ, then the total force exerted by the inclined plane on the block is:

A boy weighing 25 kg climbs up from the first floor at a height 3 m above the ground to the third floor at a height 9 m above the ground. What will be the increase in his gravitational potential energy? (Take g=10Nkg⁻¹)

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