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.
On the periodic table the best insulators are shiny metals like copper silver gold
Answer:
where m < M is delivered to the space station. Soon after, the space station's orbit is adjusted so that it is 50 km ...
Answer:
3.75 m/s south
Explanation:
Momentum before collision = momentum after collision
m₁ u₁ + m₂ u₂ = m₁ v₁ + m₂ v₂
Since the car and truck stick together, v₁ = v₂.
m₁ u₁ + m₂ u₂ = (m₁ + m₂) v
Given m₁ = 1500 kg, u₁ = -15 m/s, m₂ = 4500 kg, and u₂ = 0 m/s:
(1500 kg) (-15 m/s) + (4500 kg) (0 m/s) = (1500 kg + 4500 kg) v
-22500 kg m/s = 6000 kg v
v = -3.75 m/s
The final velocity is 3.75 m/s to the south.
Answer: If the forces on an object are balanced, the net force is zero. If the forces are unbalanced forces, the effects don't cancel each other. Any time the forces acting on an object are unbalanced, the net force is not zero, and the motion of the object changes.
