Answer:
Explanation:
Average velocity is found in the total displacement experienced in the trip divided by the total time it took to make this trip. If, for the first 2.0 hours, the car travels at 60 km/hr, then in 2.0 hours the car can travel 120 km; if it then travels for 3.0 at 85 km/hr, it can travel 255 km in the same direction. The total time this took was 5.0 hours. So doing the math and rounding correctly by following the rules for the adding and subtracting of sig fig's:

If you do not round when you add, the average velocity is 75 km/hr
Answer:
#_photon = 7 10²¹ photons
Explanation:
Let's look for the power that affects the panel of area of 1.5 m2
I = P / A
P = I A
P = 1.37 10³ 1.5
P = 2,055 10³ W
P = E / t
If we use t = 1 s
E = P t
E = 2,055 10³ J
This is the power that the panel receives, let's look for the energy of a photon
E = h f
c = λ f
f = c /λ
E = h c /λ
Let's calculate
E₀ = 6.63 10⁻³⁴ 3 10⁸/680 10⁻⁹
E₀ = 2.925 10⁻¹⁹ J
In one second the total energy is the number of photons for the energy of each one
E = #_photon E₀
#_photon = E / E₀
#_photon = 2,055 10³ / 2,925 10⁻¹⁹
#_photon = 7 10²¹ photons
19 m/s is the average velocity if the initial velocity of an object is 10 m/s and the final velocity is 28 m/s.
<u>Explanation:</u>
The initial and final velocity is given and the average velocity is asked, which can be calculated by the following method,
Given that initial velocity = 10 m/s and final velocity = 28 m/s
As we know that the average velocity = 
Although, 
But here, there is only given initial and final velocity therefore it will be simply an average of the two.

Therefore, the average velocity of the object is 19 m/s.