Answer:
H = 3.9 m
Explanation:
mass (m) = 48 kg
initial velocity (initial speed) (U) = 8.9 m/s
final velocity (V) = 1.6 m/s
acceleration due to gravity (g) = 9.8 m/s^{2}
find the height she raised her self to as she crosses the bar (H)
from energy conservation, the change in kinetic energy = change in potential energy
0.5m(V^{2} - [test]U^{2}[/tex]) = mg(H-h)
where h = initial height = 0 since she was on the ground
the equation becomes
0.5m(V^{2} - [test]U^{2}[/tex]) = mgH
0.5 x 48 x (1.6^{2} - [test]8.9^{2}[/tex]) = 48 x 9.8 x H
-1839.6 = 470.4 H (the negative sign indicates a decrease in kinetic energy so we would not be making use of it further)
H = 3.9 m
When a mirror is rotated . . .
-- The incident ray doesn't turn. It's just the line from the source to the mirror.
It would be there, in the same place, even if there was no mirror.
-- The normal turns. It's the line perpendicular to the mirror, so it must turn
with the mirror.
-- Since the normal tuns and the incident ray doesn't, the angle between them
must change. And since the angle of the reflected ray is equal to the angle of
the incident ray, the reflected ray must also turn.
This is a statement not a question .
You can use the equation V=Vo+at since the acceleration is constant. Plugging in the values you know, you will get an answer of 3.75 seconds
