20km every 1 hr is what 20km/hr means.
so 3hrs is 20km*3=60km.
Answer:
Wave theory of light explains the phenomena of interference, diffraction, scattering, dispersion, polarisation etc. Complete solution: Around 1700, it was concluded by Newton that light was a group of particles. It was called corpuscular theory.
Answer:
T = 37.08 [N*m]
Explanation:
We must remember that torque is defined as the product of a force by a distance. This distance is measured from the point of application of force to the center of rotation of the rotating body.
The force is equal to the product of mass by gravitational acceleration.
![F=m*g\\F=70*9.81\\F=686.7[N]](https://tex.z-dn.net/?f=F%3Dm%2Ag%5C%5CF%3D70%2A9.81%5C%5CF%3D686.7%5BN%5D)
Now the torque can be calculated:
![T=F*r\\T=686.7*0.054\\T=37.08[N*m]](https://tex.z-dn.net/?f=T%3DF%2Ar%5C%5CT%3D686.7%2A0.054%5C%5CT%3D37.08%5BN%2Am%5D)
(a) Let 
be the maximum linear speed with which the ball can move in a circle without breaking the cord. Its centripetal/radial acceleration has magnitude
where 
is the radius of the circle.
The tension in the cord is what makes the ball move in its plane. By Newton's second law, the maximum net force on it is
so that
Solve for :
(b) The net force equation in part (a) leads us to the relation
so that is directly proportional to the square root of . As the radius increases, the maximum linear speed will also increase, so the cord is less likely to break if we keep up the same speed.
The answer is B because if you use process of elimination, you find that A is invalid because Venus is the second planet. C is out because Mars is the 4th planet. D is out because we are nowhere near the Andromeda Galaxy. We are millions of light years away.
