How long will it take a sample of lead-212 (which has a half-life of 10.64 h) to decay to one-eighth its original strength?
Answer:
31.92 h
Explanation:
We'll begin by calculating the number of half-lives that has elapsed. This can be obtained as follow:
Original amount (N₀) = 1
Amount remaining (N) = ⅛
Number of half-lives (n) =?
N = 1/2ⁿ × N₀
⅛ = 1/2ⁿ × 1
Cross multiply
2ⁿ = 8
Express 8 in index form with 2 as the base.
2ⁿ = 2³
n = 3
Thus, 3 half-lives has elapsed.
Finally, we shall determine the time. This can be obtained as follow:
Half-life (t½) = 10.64 h
Number of half-lives (n) = 3
Time (t) =?
n = t / t½
3 = t / 10.64
Cross multiply
t = 3 × 10.64
t = 31.92 h
Therefore, it will take 31.92 h for lead-212 to decay to one-eighth its original strength.
MIDDLE SCHOOL: What are the three types of energy used when cleaning? (Please write them in order of occurrence)
Answer:
Chemical, mechanical, thermal i guess
Question 7 (5 points)
(03.06 LC)
Losing
or fewer per week is a healthy rate of weight loss. (5 points)
Answer:
true?
Explanation:
Stress is __________.
A.
positive or negative, depending on circumstances
B.
a body's automatic physical response
C.
a negative reaction to outside influences
D.
A and B only
Answer:
(A)
Explanation:
Depending on the circumstances, there are such things called good stress and bad stress.
If 10.0 J of work are required to transfer 2.00 coulombs of
charge from point X to point Y in an electric field, what is the
difference in potential between these two points?
Answer: 5V
Explanation: because 2 goes into 10, five times. Also I know it’s correct cuz I got it right in my quiz
The difference in potential between these two points is 5 V.
Electric potential between the two points
The electric potential between two points is the work done in taking a unit postive charge from one point to another.
The difference in potential between these two points is calculated as follows;
W = qV
V = W/q
V = 10/2
V = 5 V
Thus, the difference in potential between these two points is 5 V.
Learn more about electric potential here: https://brainly.com/question/14306881
5 examples of electrical energy
Answer:
its very simple this list the items that you have in your house that have electric energy
Explanation:
what is the geologic time scale and how is it used
Answer:
It is a type of map used to map out the geographical change over time. I believe
Explanation:
A cruise ship travels across a river at 25 meters per minute. If the river is 6200 meters wide, how long
does it take the ship to reach the other side.
Answer:
248 minutes
Explanation:
6200/25=248
This means there is 248 25s in 6200
which means it will take 248 minutes to travel through the river
Also here's a neat trick:
The units for speed is meters/minute
The units for distance is meters
Dividing distance by speed will cancel out the meters and leave only the speed.
how can the conductivity of a semiconductor be increased?
1. Un móvil se desplaza 20m e invierte 8 segundos en hacerlo. ¿Cuál es su velocidad instantánea? 2. Un móvil parte a 3 metros después del origen y se detiene a 2 metros antes de este. Si demora 10 segundos en su desplazamiento. Calcular su rapidez.
Answer:
1) v = 2.5 m / s, 2) v = -0.5 m / s
Explanation:
For this exercise we will use the kinematics relations
1) velocity is defined by
v = [tex]\frac{dx}{dt}[/tex]dx / dt
this definition serves for the instantaneous and the average velocity if the displacements are linear in time
v = 20/8
v = 2.5 m / s
b) for this part we use
v = [tex]\frac{\Delta x}{\Delta t}[/tex]
Δx = x_f -x₀
we must place a reference system, where the direction to the right is positive
x_f = -2 m
x₀ = +3 m
Δx = -2 -3
Δx = -5 m
we calculate
v = -5 / 10
v = -0.5 m / s
this value is a scalar
How does a “super-crest” form?
a) It is the meeting of two waves coming from two different points, traveling at the same frequency.
b) It is the separation of two waves coming from the same point, traveling at the same frequency.
Answer Quickly, Please!!!
Answer:
a.) It is the meeting of two waves coming from two different points, traveling at the same frequency.
Explanation:
Correct me if I'm wrong, it's just my own opinion. Thankyouu!
Answer:
A. It is the meeting of two waves coming from two different points, traveling at the same frequency.
Explanation:
If the crest of 1 wave meets the crest of a second wave at a given instant in time and location along the medium, a "super crest" is formed, hope this helps....
pls help Which one of the following is NOT acceleration
A.
a change in mass
B.
a change in direction
C.
an increase in velocity
D.
a decrease in velocity
Answer:
C
Explanation:
Am increase in velocity?
Answer:
change in mass is not acceleration
An electric toy with a resistance of 2.50\,\Omega is operated by a 3.00\,\text{V} battery. (c) How much energy was delivered to the toy [over four hours]?
Answer:
Energy = 51840 J = 51.84 KJ
Explanation:
The electrical energy delivered to the toy can be found out by the following formula:
[tex]Energy = (Power)(time)\\Energy = (VI)(t)\\Enegry = VIt\\[/tex]
where,
V = Voltage = 3 V
R = Resistance = 2.5 Ω
I = Current = V/R (Ohm's Law) = 3 V/2.5 Ω = 1.2 A
t = time = (4 h)(3600 s/1 h) = 14400 s
Therefore,
[tex]Energy = (3\ V)(1.2\ A)(14400\ s)\\[/tex]
Energy = 51840 J = 51.84 KJ
Calculate the weight of a 2.3 kg squirrel
Answer:
Lemme think rq
*inserts writing noises*
*insert intese thinking*
*insert big brain moment*
Well the weight IS 2.3 kg so I think the weight of a squirrel is 2.3 kg
A music fan at a swimming pool is listening to a radio on a diving platform. The radio is playing a constant- frequency tone when this fellow, clutching his radio, jumps off. Describe the Doppler Effect heard by (a) a person left behind on the platform and (b) a person down below floating on a rubber raft. In each case, specify (1) whether the frequency is greater or smaller than the frequency produced by the radio, (2) whether the observed frequency is constant, and (3) how the observed frequency changes during the fall, if it does change. Give your reasoning.
Answer:
The Doppler Effect is given by the following relation;
[tex]f' = \left (\dfrac{v + v_0}{v - v_s} \right) \times f[/tex]
Where;
f' = The frequency the observer hears
f = Actual frequency of the wave
v = The velocity of the sound wave
[tex]v_o[/tex] = The velocity of the observer
[tex]v_s[/tex] = The velocity of the source
Where the observer is stationary, we have;
(i) When the source is moving in the direction of the observer
[tex]f' = \left (\dfrac{v }{v - v_s} \right) \times f[/tex]
(ii) When the source is receding from the observer, we have;
[tex]f' = \left (\dfrac{v }{v + v_s} \right) \times f[/tex]
Therefore;
(a) A person left behind on the platform
For a person left behind on the platform, we have that the radio source is receding, therefore, we have;
[tex]f' = \left (\dfrac{v }{v + v_s} \right) \times f[/tex]
(1) Given that (v + [tex]v_s[/tex]) > v, therefore, v < (v + [tex]v_s[/tex]), f' < f, the frequency heard by the person left on the platform, f', is smaller (lower) than the frequency produced by the radio
(2) The frequency is not constant as the speed of the source is increasing while it under the acceleration due to gravity
(3) During the fall, the speed of the source continuously increases under the effect of gravitational attraction and therefore the frequency heard by the person on the platform becomes progressively smaller
(b) A person down below floating on a rubber raft
For the the person down below on the rubber raft, the radio source is advancing
Therefore, the radio source is moving towards the person at rest down on the rubber raft, therefore, we have;
[tex]f' = \left (\dfrac{v }{v - v_s} \right) \times f[/tex]
(1) Given that (v - [tex]v_s[/tex]) < v, therefore, f' > f, the frequency heard by the person down below floating on the rubber raft, f', is greater (higher) than the frequency produced by the radio
(2) The frequency is not constant as the speed of the source is increasing while it under the acceleration due to gravity
(3) During the fall, the speed of the source continuously increases under the effect of gravitational attraction and therefore the frequency heard by the person on the platform becomes progressively greater (higher)
Explanation:
One of the most dangerous side effects of an erupting volcano is a
Answer:
One of the most deadly effects of a volcano is the ash coming from the eruption, which carries poisonous gases that are harmful to humans, plants, and animals alike.
Explanation:
:))))))))
two pins attracted by a bar magnet maintain a distance between their ends why??
If a chemical reaction has a AH value of -125 kJ, it would be considered what?
Answer:
Exothermic Reaction
Explanation:
ENDOTHERMIC REACTION: A chemical reaction is considered endothermic if the energy is absorbed during the reaction. In other words, if the energy is required by the reactants to proceed with the reaction, then the reaction is endothermic.
The value of enthalpy change ΔH is positive in such reactions showing intake of energy.
EXOTHERMIC REACTION: A chemical reaction is considered exothermic if the energy is released during the reaction. In other words, if the energy is produced as a product of the reaction, then the reaction is exothermic.
The value of enthalpy change ΔH is negative in such reactions showing the release of energy.
Since, the value of ΔH = -125 KJ, is negative for the given reaction.
Therefore, it would be considered as Exothermic Reaction.
2-Write True(T) if the sentence is true. Write False(F) if the sentence is
false.
Momentum is a measure of the motion of a body equal to the product of its
mass and acceleration due to gravity.
Impulse is defined as the force times the time interval.
The tendency of an object to resist a change in motion is called Force
If the speed of an object is doubled, its momentum is multiplied by 2
Sudden change in momentum in a collision, results in a large force that can
cause injury.
Safety features of modern cars ensures that energy is not absorbed when vehicles
stop:
Crumple zones are built into cars to increase the duration of crashes.
answer right away!!—A plucked guitar string emits a dominant
frequency of 320 Hz. What is the
frequency of the 3rd harmonic?
Answer:
20000000000000hz only for this
A man is jogging to work. From his house he runs 752 meters west, turns a corner and runs 587 meters south before arriving at work. What is the mans total distance covered AND net displacement (length of displacement and angle)?
Answer:
[tex]d_t=1339m[/tex]
[tex]d_r=953.98[/tex]
[tex]x=37.975 \textdegree[/tex]
Explanation:
From the question we are told that
1st distance [tex]d_1=752 m[/tex]
2nd distance [tex]d_2=587 m[/tex]
Generally the total distance [tex]d_t[/tex]covered by the man is mathematically given as
[tex]d_t =1st\ distance +2nd\ distance[/tex]
[tex]d_t=752+587\\d_t=1339m[/tex]
Generally the resultant distance traveled is mathematically given as
[tex]d_r^2=d_1^2+d_2^2[/tex]
[tex]d_r=\sqrt{752^2+587^2}[/tex]
[tex]d_r=953.98[/tex]
Generally the angle using sine rule traveled is mathematically given as
let angle =x
[tex]\frac{sin90}{d_r} =\frac{sinx}{587}[/tex]
[tex]sinx=\frac{sin90*587}{953.98}[/tex]
[tex]x=37.975 \textdegree[/tex]
A copper atom has an atomic number of 29 and an atomic mass of 64. What
is the structure of this atom?
A. It has a central nucleus composed of 29 protons and 64 neutrons,
surrounded by an electron cloud containing 29 electrons.
B. It has a central nucleus composed of 35 protons and 29 neutrons,
surrounded by an electron cloud containing 29 electrons.
O C. It has a central nucleus composed of 29 protons and 35 neutrons,
surrounded by an electron cloud containing 29 electrons.
OD. It has a central nucleus composed of 29 protons and 29 neutrons,
surrounded by an electron cloud containing 35 electrons.
Answer:
The answer is B.
Explanation:
It has a central nucleus composed of 29 protons and 35 neutrons, surrounded by an electron cloud containing 29 electrons.
NO LINKS!!!!!! Help its urgent, PLEASE HELP!!!!!!!!!!!!!!!!
Answer:
I think ur answer would be B
Explanation:
srry if wrong
hope this helps
What does it take to be classified as a rouge wave
Answer: A 'rogue wave' is large, unexpected, and dangerous.
At the time, surface winds were light at 15 knots. ... Most reports of extreme storm waves say they look like "walls of water." They are often steep-sided with unusually deep troughs.
Explanation:
Answer:
Rogues, called 'extreme storm waves' by scientists, are those waves which are greater than twice the size of surrounding waves, are very unpredictable, and often come unexpectedly from directions other than prevailing wind and waves.
Which of the following is not a unit of volume?
A. L
B. mL
C. m^3
D. cm^2
Explanation:
D. cm^2
It's a unit for quadruple centimeters. All of the others are used to charge the amount of water in a specific bowl etc.
Ayala is making salad dressing. She mixes oil and vinegar in a blender until a smooth consistency is formed. Explain whether this is a heterogeneous or a homogeneous mixture and why
Answer:Hetero
Explanation: Honestly, same as the last guy said
Your spaceship has run out of fuel and comes to a halt halfway between the earth and the moon. Will you and your spaceship (a combined mass of 5000 kg) fall towards the moon or towards the earth? Show calculations to support your answer.
Answer:
moon
Explanation:
cause yes
Flossie blew a tire 5 minutes into the second leg, up to that point she had traveled 10 km making her speed 2 km/m. It took 2 minutes to fix her tire. Flossie had to finish within 2 minutes in order to stay even with the evil Mabel. If Flossie had 8 km left what speed will she need to win?
Answer:
4km/m
Explanation:
She was going at 2km/m, so 2 kilometers per minute. She has 2 minutes therefore she needs to double her rate to 4 kilometers per minute.
The national government would like to start a program that would give states money for flood relief. Which of the following states could most likely benefit from a program like this?
Answer:
When a disaster is declared, the Federal government, led by the Federal Emergency Management Agency (FEMA), responds at the request of, and in support of, States, Tribes, Territories, and Insular Areas and local jurisdictions impacted by a disaster.
Explanation:
Explain retrograde motion and why it confused early astronomers as they viewed the motion of objects in the sky.
Answer:
Explanation:
Retrograde motion in astronomy is, in general, orbital or rotational motion of an object in the direction opposite the rotation of its primary, that is, the central object (right figure). It may also describe other motions such as precession or nutation of an object's rotational axis. Prograde or direct motion is more normal motion in the same direction as the primary rotates. However, "retrograde" and "prograde" can also refer to an object other than the primary if so described. The direction of rotation is determined by an inertial frame of reference, such as distant fixed stars.
Retrograde motion occurs when a planet far from another planet and from which it is seen rotates at lower speed, creating the impression that it is "retrograding" with respect to the other planet.
Early astronomers get confused as they viewed the motion in the sky because they tried to explain it in terms of the geocentric theory.
Let suppose that we have a planetary system formed by a star and two planets rotating uniformly around the star. Besides, we assume that both planets are rotating at different velocities, and that planet A is more far away from the star than planet B, then the velocity of the planet A relative to planet B is:
[tex]\vec v_{A/B} = \vec {v}_{A}- \vec {v}_{B}[/tex] (1)
A retrograde motion of planet A occurs when [tex]\|\vec v_{A/B}\|\ne 0[/tex] and if [tex]\|\vec v_{A}\| < \|v_{B}\|[/tex] at least. In other words, retrograde motion exists when speed of planet A is less than speed of planet B, creating the impression that planet A is "retrograding" with respect to planet B. This question is easy to solve and to explain by considering the star as an inertial framework, base of the heliocentrical model.
Early astronomers were confused and unable to explain the phenomenon due to their adherence to geocentrical model, which assumed the Earth was the center of the solar system.
We kindly invite to check this question on retrograde motion: https://brainly.com/question/13586212
