Answer:
The image behind the mirror is called a virtual image because it cannot be projected onto a screen—the rays only appear to originate from a common point behind the mirror. If you walk behind the mirror, you cannot see the image, because the rays do not go there
Answer:
it’s the third option: 4,600,000 km
Explanation:
just took the test and that was correct
I might be wrong but I’d say the first one
Answer:
•when a food service worker touches food
Explanation:
The worker is physically putting his hands on the food, therefore contaminating it which whatever’s on his hands
-YW!! <33
Answer:
a) v = 0.8 m / s
, b)
= 0.777 m / s
, c) ΔK = 0.93 J
Explanation:
This exercise can be solved using the concepts of moment, first let's define the system as formed by the two blocks, so that the forces during the crash have been internal and the moment is conserved.
They give us the mass of block 1 (m1 = 100kg, its kinetic energy (K = 32 J), the mass of block 2 (m2 = 3.00 kg) and that it is at rest (v₀₂ = 0)
Before crash
po = m1 vo1 + m2 vo2
po = m1 vo1
After the crash
= (m1 + m2) 
a) The initial speed of the block of m1 = 100 kg, let's use the kinetic energy
K = ½ m v²
v = √2K / m
v = √ (2 32/100)
v = 0.8 m / s
b) The final speed,
p₀ =
m1 v₀1 = (m1 + m2) 
= m1 / (m1 + m2) v₀₁
The initial velocity is calculated in the previous part v₀₁ = v = 0.8 m / s
= 100 / (3 + 100) 0.8
= 0.777 m / s
c) The change in kinetic energy
Initial K₀ =
K₀ = 32 J
Final
= ½ (m1 + m2)
²
= ½ (3 + 100) 0.777²
= 31.07 J
ΔK =
- K₀
ΔK = 31.07 - 32
ΔK = -0.93 J
As it is a variation it could be given in absolute value
Part D
For this part s has the same initial kinetic energy K = 32 J, but it is block 2 (m2 = 3.00kg) in which it moves
d) we use kinetic energy
v = √ 2K / m2
v = √ (2 32/3)
v = 4.62 m / s
e) the final speed
v₀₂ = v = 4.62 m/s
p₀ = m2 v₀₂
m2 v₀₂ = (m1 + m2) 
= m2 / (m1 + m2) v₀₂
= 3 / (100 + 3) 4.62
= 0.135 m / s
f) variation of kinetic energy
= ½ (m1 + m2)
²
= ½ (3 + 100) 0.135²
= 0.9286 J
ΔK = 0.9286-32
ΔK = 31.06 J
The momentum of an object is the product between the mass m of the object and its velocity:

The truck in our problem has momentum equal to
and a mass of

so, if we re-arrange the previous formula, we can use these data to find the velocity of the truck: