-- Accelerating at the rate of 8 m/s², Andy's speed
after 30 seconds is
(8 m/s²) x (30.0 s) = 240 m/s .
-- His average speed during that time is
(1/2) (0 + 240 m/s) = 120 m/s .
-- In 30 sec at an average speed of 120 m/s,
Andy will travel a distance of
(120 m/s) x (30 sec) = 3,600 m
= 3.6 km .
"But how ? ! ?", you ask.
How in the world can Andy leave a stop light and then
cover 3.6 km = 2.24 miles in the next 30 seconds ?
The answer is: His acceleration of 8 m/s², or about 0.82 G
is what does it for him.
At that rate of acceleration ...
-- Andy achieves "Zero to 60 mph" in 3.35 seconds,
and then he keeps accelerating.
-- He hits 100 mph in 5.59 seconds after jumping the light ...
and then he keeps accelerating.
-- He hits 200 mph in 11.2 seconds after jumping the light ...
and then he keeps accelerating.
-- After accelerating at 8 m/s² for 30 seconds, Andy and his
car are moving at 537 miles per hour !
We really don't know whether he keeps accelerating,
but we kind of doubt it.
A couple of observations in conclusion:
-- We can't actually calculate his displacement with the information given.
Displacement is the distance and direction between the starting- and
ending-points, and we're not told whether Andy maintains a straight line
during this tense period, or is all over the road, adding great distance
but not a lot of displacement.
-- It's also likely that sometime during this performance, he is pulled
over to the side by an alert cop in a traffic-control helicopter, and
never actually succeeds in accomplishing the given description.
1) The half-life is the time required for a substance to reduce to half its initial value. In formulas:
(1)
where
m(t) is the amount of substance left at time t
m0 is the initial mass
is the half-life
In this problem, the half-life of the substance is 20 years:
therefore, the fraction of sample left after t=40 years will be
So, only 1/4 of the original sample will be left, which corresponds to 25%.
2) We can use again formula (1), by re-arranging it:
If we use m(t)=10 g (mass of uranium left at time t), and
(the time is equal to 4 half lifes), we get
So, the initial sample of uranium was 160 g.
Answer:
speed of molecule ∝ 1/mass of molecule.
Explanation:
The velocities of the molecules depend on their masses. That's because if the molecules are large in size, their velocity is slower. Therefore their velocity is quicker when their size is small, since the molecules can move faster.
Therefore , it can be written as
speed of molecule ∝ 1/mass of molecule.
I think its 60. I think you would subtract 144-84 to get the mass of the vinegar molecule.