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A motorboat covers a given distance in 6 hr moving downstream on a river.

A motorboat covers a given distance in 6 hr moving downstream on a river. It covers the same distance in 10 hr moving upstream. The time it takes... View Article

A man sitting in a bus travelling in a direction from West to East with a speed of 40 km/hr observes that the raindrops are falling vertically down. To another man standing on ground, the rain will appear

1) To fall vertically down 2) To fall at an angle going from West to East 3) To fall at an angle going from East to West 4) The information... View Article

A thief is running away on a straight road on a jeep moving with a speed of 9 m/s. A police man chases him on a motor cycle moving at a speed of 10 m/s. If the instantaneous separation of jeep from the motor cycle is 100 m, how long will it take for the policemen to catch the thief ?

1) 1 sec 2) 19 sec 3) 90 sec 4) 100 sec Answer: 4) 100 sec Solution: The relative velocity of policeman w.r.t the thief is 10 - 9 = 1... View Article

A river is flowing from East to West at a speed of 5m/min. A man on south bank of river, capable of swimming 10 m/min in still water, wants to swim across to river in the shortest time. He should swim

1) Due North 2) Due North- East 3) Due North-East with double the speed of river 4) None of the above Answer: 1) Due North Solution: To... View Article

A boat takes two hours to travel 8 km and back in still water. If the velocity of water is 4 km/hr, the time taken for going upstream 8 km and coming back is

1) 2 hr 2) 2 hr 40 min 3) 1 hr 20 min 4) Cannot be estimated with the information given Answer: 2) 2 hr 40 min Solution: Speed of boat... View Article

A boat crosses a river with a velocity of 8 km/hr. If the resulting velocity of boat is 10 km/hr, then the velocity of river water is

1) 4 km/hr 2) 6 km/hr 3) 8 km/hr 4) 10 km/hr Answer: 2) 6 km/hr Solution: Boat crosses a river with a velocity, VB = 8 km/hr... View Article

Two cars are moving in the same direction with the same speed 30 km/hr

Two cars are moving in the same direction with the same speed 30 km/hr. They are separated by distance of 5 km, the speed of a car moving in the... View Article

How many minimum numbers of non-zero vectors in different planes can be added to give zero resultant?

1) 2 2) 3 3) 4 4) 5 Answer: 3) 4 Solution: The minimum number of vectors having different planes which can be added to give zero... View Article

A passenger train is moving at 5 ms^-1

A passenger train is moving at 5 ms-1 . An express train is travelling at 30 ms-1, on the same track and rear side of the passenger train at some... View Article

A train of 150 m length is going towards North direction at a speed of 10 ms^-1

A train of 150 m length is going towards North direction at a speed of 10 ms-1. A parrot flies at a speed of 5 ms-1 towards South direction... View Article

Two trains are moving with equal speed in opposite directions along two parallel railway tracks

Two trains are moving with equal speed in opposite directions along two parallel railway tracks. If the wind is blowing with speed u along the... View Article

A boat crosses a river of width 1 km by shortest path in 15 min. If the speed of boat in still water is 5 kmh^-1, then what is the speed of the river?

1) 5 kmh-1 2) 12 kmh-1 3) 3 kmh-1 4) 4 kmh-1 Answer: 3) 3 kmh-1 Solution: Boat crosses a river of width 1 km by shortest path in 15... View Article

If a.b = |a x b|, then θ will be

1) 450 2) 600 3) 750 4) 300 Answer: 450 Solution: a.b = |a x b| |a||b|cos θ = |a||b| sin θ tan θ = 1... View Article

A tuning fork of frequency 440 Hz is attached to a long string of linear mass density 0.01 kg m⁻¹ kept under a tension of 49 N. The fork produces transverse waves of amplitude 0.50 mm on the string.

(a) Find the wave speed and the wavelength of the waves. (b) Find the maximum speed and acceleration of a particle of the string. (c) At what... View Article

A 200 Hz wave with amplitude 1 mm travels on a long string of linear mass density 6 g m⁻¹ kept under a tension of 60 N.

(a) Find the average power transmitted across a given point on the string. (b) Find the total energy associated with the wave in a 20 m long... View Article

A transverse wave of amplitude 0.50 mm and frequency 100 Hz is produced on a wire stretched to a tension of 100 N. If the wave speed is 100 m s⁻¹, what average power is the source transmitting to the wire?

Average power of the source = P = 2π2mva2f2...(1)v = √(T/m) = 100 m/s and m = 0.01 kg/mr = 0.5 x 10-3 and f = 100(Given)On substituting the... View Article

Two long strings A and B, each having linear mass density 12 × 10⁻² kg m⁻¹, are stretched by different tensions 48 N and 75 N respectively and are kept parallel to each other with their left ends at x = 0. Wave pulses are produced on the strings at the left ends at t = 0 on string A and at t = 20 ms on string B. When and where will the pulse on B overtake that on A?

Suppose v and v’ are wave speeds in string A and B respectively. T = 4.8 and m = 1.2 x 10-2 and T' = 7.5 Now, v = √(T/m) = 20 m/s and v' =... View Article

A heavy but uniform rope of length L is suspended from a ceiling.

(a) Write the velocity of a transverse wave travelling on the string as a function of the distance from the lower end. (b) If the rope is given... View Article

A circular loop of string rotates about its axis on a frictionless horizontal plane at a uniform rate so that the tangential speed of any particle of the string is υ. If a small transverse disturbance is produced at a point of the loop, with what speed (relative to the string) will this disturbance travel on the string?

R = Radius of the loop, m = mass per unit length of the stringω = angular velocity, V = linear velocity of the stringThe force for a small potion... View Article

A heavy ball is suspended from the ceiling of a motor car through a light string. A transverse pulse travels at a speed of 60 cm s⁻¹ on the string when the car is at rest and 62 cm s⁻¹ when the car accelerates on a horizontal road. Find the acceleration of the car. Take g = 10 m s⁻².

Tension = T = mgSpeed = v1 = √(mg/ρ)At motion:Tension = T = m√(a2+g2) and Speed = v2 = √[(m√(a2 + g2))/ρ]Now,or (A - 1)g2 = a2a2 = 0.140 x 100or... View Article

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