Aspecial spring is constructed in which the restoring force is in the opposite direction to the displacement but is proportional to the cube of the displacement; i. e., f= -kx3this spring is placed on a horizontal frictionless surface. one end of the spring is fixed, and the other end is fastened to a mass m. the mass is moved so that the spring is stretched a distance a and then released. determine each of the following in terms of k, a, and m(a) the potential energy in the spring at the instant the mass is released(b) the maximum speed of the mass

answer: the correct answer id option(d).

explanation:

snell's law refraction:

the angle of refraction =

the angle of incidence =

refractive index of air = = 1

refractive index of glycerol = 1.47

from the given options, the most closest answer to 63.72° is 65° of option (d).

air exerts forces on falling objects near earth’s surface.

explanation:

the term 'free falls' refer to object that are falling towards the earth, in a situation in which gravity is the only force acting on the object.

for an object in free fall, the acceleration is constant (g, the gravitational acceleration), and so the velocity of the object constantly increases.

for objects near earth's surface, there is always another force acting on the object: the resistance due to the air. this force is opposed to the direction of fall of the object, and it is proportional to the velocity of the object, so as the object falls down, this force increases up to a point when it balances the force of gravity, and the object continues its motion at constant velocity (called terminal velocity). since in this case gravity is not the only force acting on the object, we are not in a situation of free fall.