Gravity, friction, and air resistance are some examples.
Y - yo = Vo*t - g * (t^2) / 2
Vo = - 9.0 m/s
t = 0.50 s
=> y - yo = -9.0 m/s * 0.5 s - 9.8 m/s^2 * (0.5s)^2 / 2 = - 4.5m - 1.225m = - 5.725 m.
Answer: option c) - 5.7
Answer:
C
Explanation:
only if there is a net force of zero, the body will not move
some people may say B but that is wrong because maybe one force is greater than the other so the object would still move even though the forces are in opposite directions and parallel
Lifting a mass to a height, you give it gravitational potential energy of
(mass) x (gravity) x (height) joules.
To give it that much energy, that's how much work you do on it.
If 2,000 kg gets lifted to 1.25 meters off the ground, its potential energy is
(2,000) x (9.8) x (1.25) = 24,500 joules.
If you do it in 1 hour (3,600 seconds), then the average power is
(24,500 joules) / (3,600 seconds) = 6.8 watts.
None of these figures depends on whether the load gets lifted all at once,
or one shovel at a time, or one flake at a time.
But this certainly is NOT all the work you do. When you get a shovelful
of snow 1.25 meters off the ground, you don't drop it and walk away, and
it doesn't just float there. You typically toss it, away from where it was laying
and over onto a pile in a place where you don't care if there's a pile of snow
there. In order to toss it, you give it some kinetic energy, so that it'll continue
to sail over to the pile when it leaves the shovel. All of that kinetic energy
must also come from work that you do ... nobody else is going to take it
from you and toss it onto the pile.
