A plane is in level flight at constant speed and each of its two wings has an area of `25 m^2`. If the speed of the air is 180 km/h over the lower wing and 234 km/h over the upper wing surface, determine the plane’s mass. (Take air density to be `1 kg m^-3)`.

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 .

The blades of a windmill sweep out a circle of area A. (a) If the wind flows at a velocity v perpendicular to the circle, what is the mass of the air passing through it in time f?(b) What is the kinetic energy of the air? (c) Assume that the windmill converts 25% of the wind’s energy into electrical energy, and that A = 30 m^- 2 , v = 36 km/h and the density of air is 1.2 kg m^-3 . What is the electrical power produced?

A trolley of mass 200 kg moves with a uniform speed of 36 km/ h on a frictionless track. A child of mass 20 kg runs on the trolley from one end to the other (10 m away) with a speed of 4 m s^-1 relative to the trolley in a direction opposite to the its motion, and jumps out of the trolley. What is the final speed of the trolley? How much has the trolley moved from the time the child begins to run?

A constant force acting on a body of mass 3.0 kg changes its speed from 2.0 m s^-1 to 3.5 m s^-1 in 25 s. The direction of the motion of the body remains unchanged. What is the magnitude and direction of the force?

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) .

Two rails of a railway track insulated from each other and the ground are connected to a milli voltmeter. What is the reading of millivoltmeter when the train travels at speed of 180 km/h along the track, given that the horizontal component of earth's magnetic field is 0.2*10^(-4) wb/m and the rails are separated by 1 meter.

Two trains A and B of length 400 m each are moving on two parallel tracks with a uniform speed of 72 km h^-1 in the same direction, with A ahead of B. The driver of B decides to overtake A and accelerates by 1 m//s^-2 . If after 50 s, the guard of B just brushes past the driver of A, what was the original distance between them?

Give the magnitude and direction of the net force acting on a stone of mass 0.1 kg, (a) just after it is dropped from the window of a stationary train,(b) just after it is dropped from the window of a train running at a constant velocity of 36 km/h,just after it is dropped from the window of a train accelerating with 1 ms^2,just after it is dropped from the window of a train accelerating with 1M/S2

A body of radius R and mass m is rolling horizontally without slipping with a unifrom speed v. It then rolls up in an inclined plane to a maximum height of h. If h = (3v^2)/(4g) , determine the MI of the body about its axis of rotation.