Answer:

Explanation:
Since the hoop is rolling on the floor so its total kinetic energy is given as

now for pure rolling condition we will have

also we have

now we will have


now by work energy theorem we can say



now solve for final speed

Answer:
The magnetic force on a current-carrying wire is perpendicular to both the wire and the magnetic field with direction given by the right hand rule.
Answer: The electromagnetic waves reach Earth, while the mechanical waves do not.
Explanation:
Part a)
kinetic energy of the hammer will be

here we know that
m = 4 kg
v = 6 m/s
now by the equation of kinetic energy we have


Part b)
for finding the force we will have

here we know that



now from above equation we have


now by Newton's II law we have


so it requires 720 N.