In classical mechanics, kinetic energy (KE) is equal to half of an object's mass (1/2*m) multiplied by the velocity squared. For example, if a an object with a mass of 10 kg (m = 10 kg) is moving at a velocity of 5 meters per second (v = 5 m/s), the kinetic energy is equal to 125 Joules, or (1/2 * 10 kg) * 5 m/s2.
Answer:
Part a)

Part b)

Explanation:
Part a)
If block is sliding up then net force must be zero and friction will be in opposite to the direction of motion of the block


so we have





Part b)
If block is sliding down then net force must be zero and friction will be in opposite to the direction of motion of the block


so we have





Answer:
Shorter string produces more frequency in two different strings because the equation for frequency is velocity/wavelength , this means that a shorter string creates a shorter wavelength which essentially increases the total frequency produced
A solenoid hope this is right