If the sign of work is negative, that means the force and the motion are in opposite directions.
Let's say you see something roll off of the shelf. You catch it, and you let it down slowly and gently.
Gravity exerted down-force on it and it moved down. Gravity did positive work on it.
YOU exerted UP-force on it and it moved down. YOU did negative work on it.
(Also, the falling object exerted down-force on your hand, and your hand moved down. The falling object did positive work on your hand ! Where did THAT energy come from ? It came from the potential energy that the object had while it was on the shelf. Your hand absorbed that energy on the way down, doing negative work. So the object didn't have any kinetic energy when it reached the floor, and it did NOT splinter the floor or shatter in smithereens. It had barely enough energy left to make a sound when it hit the floor.)
Despite the risks, Human populations can be found near volcanoes. This can be associated with the availability of which natural resource?
- <em>Geothermal</em><em> </em><em>energy</em>
<u>Geothermal</u><u> </u><u>energy</u><u> </u><u>is</u><u> </u><u>the</u><u> </u><u>f</u><u>o</u><u>r</u><u>m</u><u> </u><u>of</u><u> </u><u>energy</u><u> </u><u>obtained</u><u> </u><u>from</u><u> </u><u>the</u><u> </u><u>heat</u><u> </u><u>of</u><u> </u><u>the</u><u> </u><u>earth</u><u>.</u><u> </u><u>Near</u><u> </u><u>volcanoes</u><u> </u><u>the</u><u> </u><u>land</u><u> </u><u>is</u><u> </u><u>more</u><u> </u><u>hot</u><u> </u><u>compared</u><u> </u><u>to</u><u> </u><u>the</u><u> </u><u>normal</u><u> </u><u>areas</u><u>.</u><u> </u><u>So</u><u>,</u><u> </u><u>the</u><u> </u><u>heat</u><u> </u><u>of</u><u> </u><u>the</u><u> </u><u>lava</u><u> </u><u>will</u><u> </u><u>help</u><u> </u><u>in</u><u> </u><u>producing</u><u> </u><u>Geothermal</u><u> </u><u>energy</u><u>.</u><u>.</u><u>.</u><u>~</u>
Sound intensity goes inversely as the square of the distance from the source. This is easy to understand if you think of the total sound energy spread out over the surface of a sphere with the source at the center. The surface area of the sphere goes as r^2, so the power density goes inversely as such.
The decibel change is simply
Change = 10 log10( (1/3)^2 ) = -9.54 dB
Average <u>speed</u> = (distance covered) / (time to cover the distance) =
(5m) / (15 sec) =
(5/15) (m/s) = <em>1/3 m/s</em> .
Average <u>velocity</u> =
(displacement) / (time spent traveling) in the direction of the displacement
Average velocity = (5m) / (15 sec) left =
(5/15) / (m/sec) left =
<em>1/3 m/s left</em>.
A number without a direction is a speed, not a velocity.
Answer:
The correct answer is
p = p₁ + p₂
Explanation:
Newton's second law states that force = the change of momentum produced therefore since the collision is inelstic then the change of momentum of each car is p₁ and p₂ and the force of the collition is proportional to p₁ + p₂ that is
F ∝ p₁ + p₂ and since force is directly proportional to p we have
p = p₁ + p₂