The work is being done in following cases:
A mover carries a box up a flight of stairs.
A mover carries a box across a room.
Wind blows a pool chair across the yard.
A weightlifter lifts a barbell off the ground.
These are the only cases in which work is being done. The Formula of Work is:
Work= Force applied x Distance moved.
In all of these cases force is being applied and the object on which the force is being applied move in a horizontal or Vertical direction. Thus Work is done !
Answer:
4) True. The change of direction needs an unbalanced force
Explanation:
Let us propose the resolution of the problem using Newton's second law.
F = m a
As the car is spinning the acceleration is centripetal
a = v2.r
F = m v2 / r
We can see that as the velocity of a vector even if its module does not change, the change of direction requires an external force.
Now we can analyze the statement if they are true or false
1) and 3) False, even when the speed changes, the direction changes
2) False with the speed change can be determined
4) True. The change of direction needs an unbalanced force
5) False are different things. the direction is where it is going and the speed is the magnitude of the vector
Answer:
v_average = (d₂-d₁) / Δt
this average velocity is not necessarily the velocity of the extreme points,
Explanation:
To resolve the debate, it must be shown that the two have part of the reason, the space or distance between the two points divided by time is the average speed between the points.
v_average = (d₂-d₁) / Δt
this average velocity is not necessarily the velocity of the extreme points, in the only case that it is so is when there is no acceleration.
Therefore neither of them is right.
1) 4°C : It has the highest density as shown on the graph.
2) Water expands when it freezes, making it less dense than just water.
3) The ice would sink to the bottom, then the rest of the water would freeze as well, the entire lake/river/whatever will freeze eliminating the organisms that live there.
Answer:
<em>The final speed of the second package is twice as much as the final speed of the first package.</em>
Explanation:
<u>Free Fall Motion</u>
If an object is dropped in the air, it starts a vertical movement with an acceleration equal to g=9.8 m/s^2. The speed of the object after a time t is:

And the distance traveled downwards is:

If we know the height at which the object was dropped, we can calculate the time it takes to reach the ground by solving the last equation for t:

Replacing into the first equation:

Rationalizing:

Let's call v1 the final speed of the package dropped from a height H. Thus:

Let v2 be the final speed of the package dropped from a height 4H. Thus:

Taking out the square root of 4:

Dividing v2/v1 we can compare the final speeds:

Simplifying:

The final speed of the second package is twice as much as the final speed of the first package.