The bQB of a pendulum is released from a horizontal position. If the length of the pendulum is 1.5 m, what is the speed with which the bQB arrives at the lowermost point, given that it dissipated 5% of its initial energy against air resistance?

The bob of a simple pendulum of length 1 m is' pulled aside from its equilibrium’ position through an angle 60^@ and released. Calculate the speed at which the bob passes the equilibrium position.

A-stone of mass 0.25 kg tied to the end of a string is whirled round in a circle of radius 1.5 m with a speed of 40 rev./min in a horizontal plane. What is the tension in the string? What is the maximum speed with which the stone can be whirled around if the string can withstand a maximum tension of 200. N?

A resistance wire connected in the left gap of a metre bridge balances a 10Ω resistance in the right gap at a point which divides the bridge wire in the ratio 3:2. If the length of the resistance wire is 1.5m, then find the length of 1Ω of the resistance wire.

A rain drop of radius 2 mm falls from a height of 500 m above the ground. It falls with decreasing acceleration (due to viscous resistance of the air) until at half its original height, it attains its maximum (terminal) speed, and moves with uniform speed thereafter. What is the work done by the gravitational force on the drop in the first and second half of its journey? What is the work done by the resistive force in the entire journey if its speed on reaching the ground is 10 m s-^1 ?

In a test experiment pn a model aeroplane in a wind tunnel, the flow speeds on the upper and lower surfaces of the wing are 70 m s^-1 and 63 m s^-1 respectively. What is the lift on the wing if its area is 2.5 m^2 ? Take the density of air to be 1.3 kg m^-3 .

A copper wire has diameter 0.5 mm and resistivity of 1.6 xx 10^-8Omega m. What will be the length of this wire to make its resistance 10Omega ? How much does the resistance change if the diameter is doubled?

A fighter plane flying horizontally at an altitude of .1.5 km with speed 720 km/h passes directly overhead an anti-aircraft gun. At what angle from the vertical should the gun be fired for the shell with muzzle speed 600 m s^-1 to hit the plane? At what minimum altitude should the pilot fly the plane to avoid being hit? (Take g = 10 m s^-2) .