The formula for a kinetic energy KE of a falling body is
KE = mgh
where m = mass, g = acceleration due to gravity (9.8 m/s^2, constant), h = height.
The total mass of a skateboader and a skateboard is 64 + 2.0 = 66 kg.
Finally,
KE = 66*9.8*5.0 = 32340 J
Determined by cross product or ( vector product )
Answer:
They collide, couple together, and roll away in the direction that <u>the 2m/s car was rolling in.</u>
Explanation:
We should start off with stating that the conservation of momentum is used here.
Momentum = mass * speed
Since, mass of both freight cars is the same, the speed determines which has more momentum.
Thus, the momentum of the 2 m/s freight car is twice that of the 1 m/s freight car.
The final speed is calculated as below:
mass * (velocity of first freight car) + mass * (velocity of second freight car) = (mass of both freight cars) * final velocity
(m * V1) + (m * V2) = (2m * V)
Let's substitute the velocities 1m/s for the first car, and - 2m/s for the second. (since the second is opposite in direction)
We get:

solving this we get:
V = - 0.5 m/s
Thus we can see that both cars will roll away in the direction that the 2 m/s car was going in. (because of the negative sign in the answer)
Answer:
The linear charge density is 5.19 X 10⁻⁶ C/m
Explanation:
The potential difference between two cylinders, is given as
V = (λ/2πε)ln(b/a)
where;
λ is the line charge density on the power line.
b is the distance between the power line = 1 m
a is the radius of the wire = 1.5 cm = 0.015 m
ε is the permittivity of free space = 8.9 X 10⁻¹² C
V*2πε = λ* ln(b/a)
3900 *(2π*8.9 x10⁻¹²)= λ *ln(1/0.015)
2.1812 X 10⁻⁷ = 4.1997* λ
λ = 5.19 X 10⁻⁶ C/m
Therefore, the linear charge density is 5.19 X 10⁻⁶ C/m