Positions and velocities of a metal ball released from rest when air resistance is negligible. Velocity is seen to increase linearly with time while displacement increases with time squared. Acceleration is a constant and is equal to gravitational acceleration.
Suppose the ball falls 1.0000 m in 0.45173 s. Assuming the ball is not affected by air resistance, what is the precise acceleration due to gravity at this location?
Strategy
Draw a sketch.
We need to solve for acceleration
. Note that in this case, displacement is downward and therefore negative, as is acceleration.
Solution
1. Identify the knowns.
;
;
;
.
2. Choose the equation that allows you to solve for
using the known values.
3. Substitute 0 for
and rearrange the equation to solve for
. Substituting 0 for
yields
Solving for
gives
4. Substitute known values yields
so, because
with the directions we have chosen,
Discussion
The negative value for
indicates that the gravitational acceleration is downward, as expected. We expect the value to be somewhere around the average value of
, so
makes sense. Since the data going into the calculation are relatively precise, this value for
is more precise than the average value of
; it represents the local value for the acceleration due to gravity.
A chunk of ice breaks off a glacier and falls 30.0 meters before it hits the water. Assuming it falls freely (there is no air resistance), how long does it take to hit the water?
We know that initial position
, final position
, and
. We can then use the equation
to solve for
. Inserting
, we obtain
where we take the positive value as the physically relevant answer. Thus, it takes about 2.5 seconds for the piece of ice to hit the water.
Learn about graphing polynomials. The shape of the curve changes as the constants are adjusted. View the curves for the individual terms (e.g.
) to see how they add to generate the polynomial curve.
An object in free-fall experiences constant acceleration if air resistance is negligible.
On Earth, all free-falling objects have an acceleration due to gravity
, which averages
Whether the acceleration
a should be taken as
or
is determined by your choice of coordinate system. If you choose the upward direction as positive,
is negative. In the opposite case,
is positive. Since acceleration is constant, the kinematic equations above can be applied with the appropriate
or
substituted for
.
For objects in free-fall, up is normally taken as positive for displacement, velocity, and acceleration.
Conceptual questions
What is the acceleration of a rock thrown straight upward on the way up? At the top of its flight? On the way down?
Bacteria doesn't produce energy they are dependent upon their substrate in case of lack of nutrients they are able to make spores which helps them to sustain in harsh environments
_Adnan
But not all bacteria make spores, l mean Eukaryotic cells have Mitochondria which acts as powerhouse for them, since bacteria don't have it, what is the substitution for it?
Assimilatory nitrate reduction is a process that occurs in some microorganisms, such as bacteria and archaea, in which nitrate (NO3-) is reduced to nitrite (NO2-), and then further reduced to ammonia (NH3).
Elkana
This process is called assimilatory nitrate reduction because the nitrogen that is produced is incorporated in the cells of microorganisms where it can be used in the synthesis of amino acids and other nitrogen products
There are nothing like emergency disease but there are some common medical emergency which can occur simultaneously like Bleeding,heart attack,Breathing difficulties,severe pain heart stock.Hope you will get my point .Have a nice day ❣️
_Adnan
define infection ,prevention and control
Innocent
I think infection prevention and control is the avoidance of all things we do that gives out break of infections and promotion of health practices that promote life
