Answer:
Earth-orbiting astronauts are weightless for the same reasons that riders of a free-falling amusement park ride or a free-falling elevator are weightless. They are weightless because there is no external contact force pushing or pulling upon their body. In each case, gravity is the only force acting upon their body.
Because Any object or substance that is less dense than a fluid will float in that fluid, so hot water rises (floats) in colder water. When fluids are cooled, they contract and therefore become more dense. Any object or substance that is more dense than a fluid will sink in that fluid, so cold water sinks in warmer water
Explanation:
Given that,
Wavelength of light, 
Angle, 
We need to find the slit spacing for diffraction. For a diffraction, the first order principal maximum is given by :
n is 1 here
d is slit spacing
So, the slit spacing is 
.
Answer:
It attracts ferrous materials
Explanation:
A magnet attracts ferrous materials A ferrous materials are metallic substances or conductors that can conduct heat and electricity. Example of this ferrous materials includes iron, metal etc. Since magnets only can attracts metallic substance to itself, then we can also conclude that they attract ferrous materials since ferrous materials. possesses properties of a metal.
Magnets possesses both north and south poles.
The same of the bar magnets are known to repel each other while unlike poles attract each other.
Answer:
4.1 m
Explanation:
10 kW = 10000 W
20mi/h = 20*1.6 km/mi = 32 km/h = 32 * 1000 (m/km) *(1/3600) hr/s = 8.89 m/s
The power yielded by the wind turbine can be calculated using the following formula
where 
is the air density, v = 8.89 m/s is the wind speed, A is the swept area and 
is the efficiency
The swept area is a circle with radius r being the blade length
