Answer:
The velocity of the skateboard is 0.774 m/s.
Explanation:
Given that,
The spring constant of the spring, k = 3086 N/m
The spring is stretched 18 cm or 0.18 m
Mass of the student, m = 100 kg
Potential energy of the spring, 
To find,
The velocity of the car.
Solution,
It is a case of conservation of energy. The total energy of the system remains conserved. So,






v = 0.774 m/s
So, the velocity of the skateboard is 0.774 m/s.
Because many fuels are fossil fuels they take millions of years to form and the known reserves are being used much faster than the new ones being made
Your answer is c steam because steam is a gas...
Answer:

Explanation:
<u>Density
</u>
The density of a substance is the mass per unit volume. The density varies with temperature and pressure.
The formula to calculate the density of a substance of mass (m) and volume (V) is:

We have a cube-shaped piece of copper of 4 cm of side length. The volume of the piece is:

Surprisingly, no other magnitude is required, thus the answer is:

Answer:
6.575
Explanation:
T1 = 30C = 30 + 273 = 303 K
T2 = - 10 C = - 10 + 273 = 263 K
The coefficient of performance of heat pump
k = T2 / (T1 - T2)
k = 263 / (303 - 263) = 6.575