Answer:
a) m=20000Kg
b) v=0.214m/s
Explanation:
We will separate the problem in 3 parts, part A when there were no coals on the car, part B when there is 1 coal on the car and part C when there are 2 coals on the car. Inertia is the mass in this case.
For each part, and since the coals are thrown vertically, the horizontal linear momentum p=mv must be conserved, that is,
, were each velocity refers to the one of the car (with the eventual coals on it) for each part, and each mass the mass of the car (with the eventual coals on it) also for each part. We will write the mass of the hopper car as
, and the mass of the first and second coals as
and
respectively
We start with the transition between parts A and B, so we have:

Which means

And since we want the mass of the first coal thrown (
) we do:



Substituting values we obtain

For the transition between parts B and C, we can write:

Which means

Since we want the new final speed of the car (
) we do:

Substituting values we obtain

Answer:
0.0000000010 joules
Explanation:
Amount : 1540.3 nanojoules (nJ)
Equals : 0.0 joules (J)
Answer:
The force exerted by the rope on her arms is 273.7 N = 0.274 kN
Explanation:
Step 1: Data given
Mass of the ice skater = 55.6 kg
Velocity = 1.73 m/s
She then moves in a circle of radius 0.608 m around the pole.
Step 2:
Force exterted by the horizontal rope is the centripetal force acting on theice skater:
Fc = M*ac
⇒ with ac = v²/r
Fc = M * v²/r
Fc = 55.6 * 1.73²/0.608
Fc =273.69 N
The force exerted by the rope on her arms is 273.7 N = 0.274 kN