Answer:
-20 kg.m/s
Explanation:
We have an object moving at 5 m/s with mass 5 kg. The initial momentum is:
pi = m × vi
pi = 5 kg × 5 m/s = 25 kg.m/s
It undergoes a quick collision with some other object and now moves at 1 m/s. The final momentum is:
pf = m × vf
pf = 5 kg × 1 m/s = 5 kg.m/s
The change in the object's momentum is:
Δp = pf - pi
Δp = 5 kg.m/s - 25 kg.m/s = -20 kg.m/s
Answer:
-3802 m/s
Explanation:
The y-component of the final velocity is ...
(6598 m/s)·sin(-20.5°) ≈ -2310.7 m/s
The y-component of the velocity due to acceleration is ...
(5200 m/s²)(0.350 s)sin(55°) ≈ 1490.9 m/s
Then the initial velocity in the y-direction is found from ...
initial velocity + change in velocity = final velocity
initial velocity = (final velocity) - (change in velocity)
= -2310.7 m/s - 1490.9 m/s ≈ -3802 m/s
You say to yourself "Self ! Energy can't be created or destroyed.
The skier's kinetic energy at the bottom of the hill is exactly the
potential energy s/he had at the top."
Potential energy at the top = (mass) (gravity) (height)
= (65.8 kg) (9.8 m/s²) (521 m)
= (65.8 x 9.8 x 521) kg-m²/s²
= 335,961.6 joules .
Part-a: No energy is lost on the way down.
Kinetic energy at the bottom = (1/2) (mass) (speed²)
335,961.6 joules = (1/2) (65.8 kg) (speed²)
335,961.6 joules / 32.9 kg = speed²
335,961.6 kg-m²/s² / 32.9 kg = speed²
(335,961.6 / 32.9) m²/s² = speed²
speed = 101 m/s
___________________________________________
Part b: Energy is lost on the way down.
Just subtract the 1.4 x 10⁵ J of energy away from the 335,961.6 J
before you do the Kinetic Energy calculation at the bottom of the hill.
The skier lost that much energy on the way down, by scraping against
snow and air and stuff, so it isn't available to make speed at the bottom.
<span>If you can't measure the parallax that means that the star is far far away, beyond all possible reach of humanity with its current technology. The closer the star is the greater the parallax, so you either get a bigger, more powerful telescope, or you just accept that it's too far away to be measured at all. Eventually the technology will develop enough to measure it.</span>
