A helicopter of mass 1000 kg rises with a vertical acceleration of 15 m s^2. The crew and the passengers weigh 300 kg. Give the magnitude and direction of the (a) force on the floor by the crew and passengers, (b) action of the rotor of the helicopter on the surrounding air, (c) force on the helicopter due to the surrounding air.

Ten one-rupee coins are put on top of each other on a table. Each coin has a mass m. Give the magnitude and direction of (a) the force on the 7th coin (counted from the bottom) due to all the coins on its top,(b) the force on the 7th coin by the eighth coin, (c) the reaction of the 6th coin on the 7th coin.

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?

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?

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

In Millikan’s oil drop experiment, what is the terminal speed of an uncharged drop of radius 2.0 xx 10^-5m and density 1.2 xx 10^3 kg m^-3 ? Take the viscosity of air at the temperature of the experiment to be 1.8 xx 10^-5 Pa s. How much is the viscous force on the drop at that speed? Neglect buoyancy of the drop due to air.