1) An electric driller comes to rest faster than an electric grinder after switiching it off?Why?
2) The cap of a pen can be opened with the help of 2 fingers. Why?
3) Why a helicopter has 2 propellers ?
4) Is a ladder more likely to slip when a person stands on it at the bottom or at the top?
5) The speed of the Earth increases when it comes closer to the Sun, in the orbit of the Earth. Why?
6) Why is it more difficult to revolve a stone by tying it to a longer string than by tying it to a shorter string?
1) An electric driller comes to rest faster than an electric grinder after switiching it off?Why?
2) The cap of a pen can be opened with the help of 2 fingers. Why?
3) Why a helicopter has 2 propellers ?
4) Is a ladder more likely to slip when a person stands on it at the bottom or at the top?
5) The speed of the Earth increases when it comes closer to the Sun, in the orbit of the Earth. Why?
6) Why is it more difficult to revolve a stone by tying it to a longer string than by tying it to a shorter string?
3) The main rotor produces lift by re-directing the flow of air downward. Due to the torque created from spinning the main rotor, with just the main rotor the helicopter's fuselage (body) would rotate the opposite way until it reached a speed which was equal and opposite the torque/resistance.
The tail rotor counteracts the torque on the main rotor by creating a similar re-direction of air. Therefore torque turns the aircraft one way and the tail rotors thrust turns it the other. To turn the opposite way as the blades rotate you simply remove the tail rotor thrust.
All helicopters need some means of generating this counter-force. There is a "Notar" (No Tail Rotor) which uses the Coanda effect to produce the counter-force.
2) Because you're applying twice the torque
3) The main rotor produces lift by re-directing the flow of air downward. Due to the torque created from spinning the main rotor, with just the main rotor the helicopter's fuselage (body) would rotate the opposite way until it reached a speed which was equal and opposite the torque/resistance.
The tail rotor counteracts the torque on the main rotor by creating a similar re-direction of air. Therefore torque turns the aircraft one way and the tail rotors thrust turns it the other. To turn the opposite way as the blades rotate you simply remove the tail rotor thrust.
All helicopters need some means of generating this counter-force. There is a "Notar" (No Tail Rotor) which uses the Coanda effect to produce the counter-force.
2) Because you're applying twice the torque
