Answer:
300000 J / 400 J/s = 750 s = 12.5 minutes
Explanation:
psychologist counseling would be the correct answer I believe
In order to make the athletic shoe to slide faster of a given surface you had to reduce the friction coefficient of the shoe with the surface.
One way to do that is to put some grease of the sole of the shoe, which undoubtedly would reduce the friction coefficient drastically and the shoe would slide more easily.
Also, if you make the sole smoother the shoe the friction coefficient would decrease and, again, the show would slide mor easily.
(a) 3.5 Hz
The angular frequency in a spring-mass system is given by

where
k is the spring constant
m is the mass
Here in this problem we have
k = 160 N/m
m = 0.340 kg
So the angular frequency is

And the frequency of the motion instead is given by:

(b) 0.021 m
The block is oscillating up and down together with the upper end of the spring. The block will lose contact with the spring when the direction of motion of the spring changes: this occurs when the spring is at maximum displacement, so at
x = A
where A is the amplitude of the motion.
The maximum displacement is given by Hook's law:

where
F is the force applied initially to the spring, so it is equal to the weight of the block:

k = 160 N/m is the spring constant
Solving for A, we find
