Answer: The correct answer is-15 Volts.
Explanation-
Voltage of a battery can be defined as the difference in electric potential that lies between the positive and negative terminals of a battery.
It can be calculated using Ohm's law, which states that the electric potential difference between two points on a circuit is equal to the product of the current that flows between the two points (I) and the total resistance that sis present between the two points. It can be mathematically depicted as-
ΔV = I • R
Putting the value of 'I' and 'R', we get-
ΔV = 5 X 3
= 15 V
Answer:

Explanation:
First, we write the equations of motion for each axis. Since the crate is sliding with constant speed, its acceleration is zero. Then, we have:

Where T is the tension in the rope, F is the force exerted by the first worker, f_k is the frictional force, N is the normal force and mg is the weight of the crate.
Since
and
, we can rewrite the first equation as:

Now, we solve for
and calculate it:

This means that the crate's coefficient of kinetic friction on the floor is 0.18.
I’m sorry if i took up a lot of space, hope this is a valid approximate answer
Answer:
15 watt
Explanation:
Power is the rate at which work is done.
This means you divide the work done with the amount of time used to perform the work.
The formula for Power is : P = W/t where;
W= work done in J = 45
t= time in seconds = 3 sec
P= 45/ 3 = 15 watt
Answer:
3 photons
Explanation:
The energy of a photon E can be calculated using this formula:

Where
corresponds to Plank constant (6.626070x10^-34Js),
is the speed of light in the vacuum (299792458m/s) and
is the wavelength of the photon(in this case 800nm).

Tranform the units

The band Gap is 4eV, divide the band gap between the energy of the photon:

Rounding to the next integrer: 3.
Three photons are the minimum to equal or exceed the band gap.