Answer:
A) The crossbeam is moving relative to the observer on the platform so the height appears contracted.
Explanation:
The observer on the train and the beam are in the same reference frame. That means observer on the train will measure the proper length of the beam not the contracted length . the observer is outside and the plank is in the moving system,it will appear to be moving.
Answer:
All i kno is that that kid ain't gonna be ok
Explanation:
if u tell me how to do it ill do it
Do you mean in general or in a piece of paper?
Part a)
Magnitude of electric field is given by force per unit charge



Part b)
Electrostatic force on the proton is given as
F = qE


PART C)
Gravitational force is given by



PART d)
Ratio of electric force to weight


Answer:
A) how your body uses oxygen