Lien is pushing a box across a table. She used a force of 100 N to get the box moving. Which force did she overcome to get the b

Explanation:

Efficiency can be expressed as the ratio of useful output to the total power consumed.

The fan delivers 500W as useful output while wasting 300W. Thus, the overall power consumed equals 800W (500 + 300).

The light's wavelength absorbed during the transition is 459 nm. Energy difference between the 5-d and the 6-s sub-levels in gold is expressed as ΔE. Let the wavelength associated with the electron's transition from the 5-d to the 6-s state be λ. The relationship that describes the connection between energy and wavelength is defined as: E = hc/λ, where E stands for photon energy, h represents Planck's constant, c is the speed of light, and λ denotes the wavelength of the photon. Therefore, the absorption wavelength in this transition stands at 459 nm.

The question pertains to the change in frequency of a wave noted by an observer moving in relation to the source, indicating that the concept to invoke is "Doppler's effect."

The standard formula for the Doppler effect is:
-- (A)

Note that we don’t need to be concerned with the signs here, as all entities are moving toward each other. If something was moving away, a negative sign would apply, but that is not relevant to this scenario.

Where,
g = Speed of sound = 340m/s.
= Velocity of the observer relative to the medium =?.
= Velocity of the source in relation to the medium = 0 m/s.
=  Frequency emitted from the source = 400 Hz.
= Frequency recognized by the observer = 408 Hz.

Substituting the given values into equation (A) will yield:





Solving the above will result in,
= 6.8 m/s

The correct result = 6.8m/s

The work done can be calculated using the equation:

Work = Force x Distance = Change in kinetic energy

The kinetic energy is derived using the following formula: KE = (1/2)*m*v^2
Thus, the change in kinetic energy is calculated as (1/2)*m*(Vf)^2 - (1/2)*m*(Vo)^2

Where:

Vf represents the final speed = 90 kph = 25 m/s
Vo denotes the initial speed = 72 kph = 20 m/s

By substituting in the given values:

Work = (1/2)*2500*(25^2) - (1/2)*2500*(20^2) = 281250 J, which can also be represented as 2.8 x 10^5 Joules.

The correct choice among the options is A.

Answer:

The canyon measures 50.176 meters deep.

Explanation:

The student drops a rock from the rim of the canyon, requiring us to ascertain the depth of the canyon—name how far the ground is below the cliff.

The data we have:

Time = t = 3.2 s

Initial velocity = = 0 m/s

Gravitational acceleration = g = 9.8 m/s²

Height = h =?

According to the second equation of motion

Given the initial velocity is zero, the right-hand side of the equation simplifies to zero

h = (0.5)(9.8)(3.2)²

h = 50.176 m

This calculation indicates that the rock dropped a distance of 50.176 meters to reach the canyon's base. Thus, the canyon depth is 50.176 meters.