Answer:
166 666 666.7 years
Explanation:
We start the question by making the units uniform. We are told that the continents move at 3 cm/year = 0.03 m/year.
We are also told that the continents are now 5000 km = 5 000 000 m apart
So to calculate the time it took for them to be this far apart
t = distance/speed
t = 5 000 000 m/(0.03 m/year) = 166 666 666.7 years
Answer:
The heavier piece acquired 2800 J kinetic energy
Explanation:
From the principle of conservation of linear momentum:
0 = M₁v₁ - M₂v₂
M₁v₁ = M₂v₂
let the second piece be the heavier mass, then
M₁v₁ = (2M₁)v₂
v₁ = 2v₂ and v₂ = ¹/₂ v₁
From the principle of conservation of kinetic energy:
¹/₂ K.E₁ + ¹/₂ K.E₂ = 8400 J
¹/₂ M₁(v₁)² + ¹/₂ (2M₁)(¹/₂v₁)² = 8400
¹/₂ M₁(v₁)² + ¹/₄M₁(v₁)² = 8400
K.E₁ + ¹/₂K.E₁ = 8400
Now, we determine K.E₁ and note that K.E₂ = ¹/₂K.E₁
1.5 K.E₁ = 8400
K.E₁ = 8400/1.5
K.E₁ = 5600 J
K.E₂ = ¹/₂K.E₁ = 0.5*5600 J = 2800 J
Therefore, the heavier piece acquired 2800 J kinetic energy
pshyical change is a usually reversible change of a substance, as size or shape: Freezing a liquid is a physical change. Compare chemical change.
internal change is when the movement of the particles increases
specific latent heat is the amount of energy per kg (unit mass) required to change ice to water without change in temperature.
