Answer:
Magnitude of the force is 2601.9 N
Explanation:
m = 450 kg
coefficient of static friction μs = 0.73
coefficient of kinetic friction is μk = 0.59
The force required to start crate moving is
.
but once crate starts moving the force of friction is reduced
.
Hence to keep crate moving at constant velocity we have to reduce the force pushing crate ie
.
Then the above pushing force will equal the frictional force due to kinetic friction and constant velocity is possible as forces are balanced.
Magnitude of the force

Answer:
Terminal velocity of object = 12.58 m/s
Explanation:
We know that the terminal velocity is attained when drag force and gravitational force are of the same magnitude.
Gravitational force = mg = 80 * 9.8 = 784 N
Drag force = 
Equating both, we have

So v = 12.58 m/s or v = -15.58 m/s ( not possible)
So terminal velocity of object = 12.58 m/s
Answer:
Increase the amplitude
Explanation:
The energy conveyed by a wave is directly proportional to the square of its amplitude. Thus; E ∝ A²
This means that increasing the amplitude will lead to an increase in the energy.
Now, the amplitude of a wave is the height of a wave from it's highest point known as the peak, to the lowest point on the wave known as the trough whereas wavelength refers to the length of a wave from one peak to the next.
This means that increasing the amplitude has no effect on the wavelength.