A) the resistance is increasing
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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.
Answer:
The speed of the car, v = 19.997 m/s
Explanation:
Given,
The centripetal acceleration of the car, a = 13.33 m/s²
The radius of the curve, r = 30 m
The centripetal force acting on the car is given by the formula
F = mv²/r
Where v²/r is the acceleration component of the force
a = v²/r
Substituting the values in the above equation
13.33 = v²/30
v² = 13.33 x 30
v² = 399.9
v = 19.997 m/s
Hence, the speed of the car, v = 19.997 m/s
Answer:
a

b

Explanation:
From the question we are told that
The mass of the rock is 
The length of the small object from the rock is 
The length of the small object from the branch 
An image representing this lever set-up is shown on the first uploaded image
Here the small object acts as a fulcrum
The force exerted by the weight of the rock is mathematically evaluated as

substituting values


So at equilibrium the sum of the moment about the fulcrum is mathematically represented as

Here
is very small so
and 
Hence

=> 
substituting values


The mechanical advantage is mathematically evaluated as

substituting values


Internal energy cannot be transferred whereas, thermal energy is the energy due to temperature difference