PLEASE HELP. A substance decays according the the equation ae^-0.0025t, where t is in minutes. Find the half life of the substance. Round to the nearest tenth.
Answers
First of all, that's not an equation. An equation needs an 'equals' sign ( = ),
so you need something like
Amount present = a e^-0.0025t .
'a' = amount present when t = 0 .
The half-life is the time it takes for the original amount to decay to half of it.
That's just 't' when e^-0.0025t = 1/2
Take the natural log of each side: -0.0025t = ln(0.5)
Divide each side by -0.0025 : t = ln(0.5) / (-0.0025) =
(-0.69315) / (-0.0025) =
t = 277.26 minutes
( 4hrs 37min 15.5sec)
Rounded to nearest tenth: t = 277.3 minutes .
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Lookattheattachedpicture
Hope itwillbehelpfultoyou..
A. Yes
B. No
Answers
Answer:
Yes
Explanation:
Neglecting air resistance, the total mechanical energy of the system would be conserved because the two forces acting on the weight are the spring force and the gravitational force, and both are conservative in nature.
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Prior to determining the experimental design, a scientist typically forms a hypothesis. The answer is letter B. this is to prepare the scientist, the possible outcome of their research before the experimental design whether they are wrong or not.
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Answer:
73.8 N
Explanation:
The total volume is,
V =
=
= 0.1396 m
The average density is,
=
= 7.169 g/cm³
The linear mass density is,
μ = pπr²
= (7.169 x 10⁹) (π (0.3 x 10⁻³)²)
= 2.026 x 10⁻³ Kg/m
The fundamental mode of length is,
L = λ/2
λ=2L
= 2 x 0.65
= 1.3 m
The speed of the wave is,
v = λf
= 1.3 m x 147 Hz
= 1.91 m/s
The tension is,
v = √T/ц
T = ц v²
= 2.026 x 10⁻³)(1.91 m/s)²
= 73.769N
73.8N
Answers
Answers
Answer:
Explanation:
We should know that the gradient(slope) of a distance-time graph is the speed, and the gradient of a velocity-time graph is the acceleration.
a) Since the gradient from t=80 to 160 is 0, the speed is 0, indicating it is at rest.
b)To find the speed, we find the gradient of the graph at t=40. Since it is a straight line from t=40 to 60, we can do this simply by
Gradient = (200-120)/(60-40)=80/20=4 (This is an estimate since the graph is not clear, instead of t=40 and t=60, you can use any two points along that straight line (from about t=20 to 60))
c)The one on the right is the velocity graph, and the one on the left shows acceleration. We can know this by analysing some points. For example, and t=50, the right graph is about constant at 5, while the left one is 0. This would indicate that the left one shows the gradient of the right (gradient of a constant portion is 0). We can choose another place on the right graph, say t=60 to 80. The curve is decreasing. The left graph for this same time period is negative. This reaffirms our guess, since the gradient of a decreasing curve should be negative.
If you want to do it the other way around, you can analyse the left graph. From about t=15 to t=30 the graph is decreasing. Thus its slope should be negative. However, the right graph is positive for this period. This means that the right graph definately does not show the slope of the left.
When you learn about calculus and derivatives, these will become much clearer :)