Answer:
The correct option is;
a. 12.5 g
Explanation:
The given parameters are;
The initial mass of the radioactive substance = 200 g
The half life of the radioactive substance = 50 years
The time duration for the disintegration = 200 years
The formula for half life is given as follows;
[tex]N(t) = N_0 \left (\dfrac{1}{2} \right )^{\dfrac{t}{t_{1/2}}[/tex]
Where:
N(t) = Quantity of the remaining substance
N₀ = Initial radioactive substance quantity = 200 g
t = Time duration = 200 years
[tex]t_{1/2}[/tex] = Half life of the radioactive substance 50 years
Therefore, we have;
[tex]N(t) =200 \times \left (\dfrac{1}{2} \right )^{\dfrac{200}{50} } =200 \times \left (\dfrac{1}{2} \right )^4 = 12.5 \ g[/tex]
Therefore, at the end of 200 years, the quantity left = 12.5 g.
Please Help
A skydiver jumps out of a hovering helicopter, so there is no forward velocity. Use this information to answer questions. Ignore wind resistance for this exercise.
3. What is the skydiver's velocity after one second? Show your work and include direction.
Answer:
The velocity and direction after 1 second is 8.1 m/s downwards
Explanation:
The equation of motion for an object in free fall can be written as follows;
v = u + g×t
Where;
v = The final velocity of the object
u = The initial velocity of the object = 0 m/s
g = The acceleration due to gravity = 9.81 m/s²
The velocity after one second is given by the velocity equation as follows;
v = 0 + 9.81 m/s² * 1 s = 9.81 m/s
The direction of the is downwards due to the attraction by the Earth's gravitational field which acts towards the Earth's center
Therefore, the velocity and direction after 1 second is 8.1 m/s downwards.
WILLL GIVE 5 STARS BRAINIEST AND THANKS AND 20 POINTS EACH ANSWER!!!!
A diver performs a dive from a 10 m-platform. She
jumps vertically upwards at 3 m s initially.
Find the time she takes to reach the water surface
Answer:
The time she takes to reach the water from when she jumps off the platform is 1.71 s
Explanation:
According to the equations of motion, we have;
v = u - g·t
v² = u² - 2·g·s
s₁ = u₁·t₁ + 1/2·g₁·t₁²
The given parameters are;
The height of the platform (assumption: above the water) = 10 m
The velocity with which she jumps, u = 3 m/s
The acceleration due to gravity, g = 9.81 m/s²
The height to which she jumps, s, is found as follows;
v² = u² - 2·g·s
At maximum height, v = 0, which gives;
0 = 3² - 2×9.81×s
2×9.81×s = 3² = 9
s = 9/(2×9.81) = 0.4587 m
s = 0.4587 m
The time to maximum height, t, is found as follows;
v = u - g·t
0 = 3 - 9.81×t
9.81×t = 3
t = 3/9.81 = 0.3058 s
The total distance, s₁ from maximum height to the water surface = s + 10 = 0.4587 + 10 = 10.4587 m = 10.46 m
The time to reach the water from maximum height, t₁, is found as follows;
s₁ = u₁·t₁ + 1/2·g₁·t₁²
Where;
s₁ = The total distance from maximum height to the water surface = 10.46 m
u₁ = The initial velocity, this time from the maximum height = 0 m/s
g₁ = The acceleration due to gravity, g (positive this time as the diver is accelerating down) = 9.81 m/s²
t₁ = The time to reach the water from maximum height
Substituting the values gives;
s₁ = u₁·t₁ + 1/2·g₁·t₁²
10.46 = 0·t₁ + 1/2·9.81·t₁²
t₁²= 10.46/(1/2×9.81) = 2.13 s²
t₁ = √2.13 = 1.46 s
Total time = t₁ + t = 1.46 + 0.3058 = 1.7066 ≈ 1.71 s.
Therefore, the time she takes to reach the water from when she jumps off the platform = 1.71 s.
Question 5
Calculate the kinetic energy of a car (m - 800 kg) moving at 15 m/s. Write your answer to the nearest whole number in the blank space
provided. Only write the numerical value of the answer without units. Do not leave any space in between numbers.
Answer: Joules
Answer:
90,000Explanation:
[tex]m =800kg\\v = 15\\\\K.E = \frac{1}{2}mv^2\\ K.E= \frac{1}{2} \times 800\times 15^2\\= 400 \times 225\\= 90000 joules\\= 90 kilojoules[/tex]
What kind of glass is used for car head lamp
Answer:
borosilicate glass
Explanation:
headlamp glass is a borosilicate glass by gravity feed
lab safety test Safety goggles and an apron must be worn when handling chemicals labeled corrosive because they:________.
Answer: React with the skin
Explanation:
lab safety test Safety goggles and an apron must be worn when handling chemicals labeled corrosive because they React with the skin
Does the surface tension of water affect the rate of evaporation? If so, would adding a surfactant speed up evaporation?
Answer:
The evaporation time gradually increased with the increase in surfactant concentration, i.e., from water to the concentration level of 0.005%. Furthermore, the evaporation time is significantly reduced, even lower than that of water containing relatively high concentrations from 0.01% to 0.1%.
A metal ring 4.30 cm in diameter is placed between the north and south poles of large magnets with the plane of its area perpendicular to the magnetic field. These magnets produce an initial uniform field of 1.12 T between them but are gradually pulled apart, causing this field to remain uniform but decrease steadily at 0.230 T/s.(a) What is the magnitude of the electric field induced in the ring? (b) In which direction (clockwise or counterclockwise) does the current flow as viewed by someone on the south pole of the magnet?
Answer:
A)0.00966 N/C
B) counterclockwise direction
Explanation:
We are given;
Diameter of the metal ring; d = 4.3 cm
Radius;r = 2.15 cm = 0.021- m
Initial magnetic field, B = 1.12 T
Rate of decrease of the magnetic field;dB/dt = 0.23 T/s
Now, as a result of change in magnetic field, an emf will be induced in it. Thus, , electric field is induced and given by the formula :
∫E•dr = d/dt∫B.A •dA
This gives;
E(2πr) = dB/dt(πr²)
Gives;. 2E = dB/dt(r)
E = dB/dt × 2r
We are given;
E = 0.23 × 2(0.021)
E = 0.00966 N/C
The magnitude of the electric field induced in the ring has a magnitude of 0.00966 N/C
B) The direction of electric field will be in a counterclock wise direction when viewed by someone on the south pole of the magnet
A skydiver falls toward the ground at a constant velocity. Which statement best applies Newton’s laws of motion to explain the skydiver’s motion? An upward force balances the downward force of gravity on the skydiver. The skydiver’s inertia is zero, which no longer allows for acceleration. An unbalanced force pulls the skydiver toward the ground. The mass of the skydiver is so great that there is no acceleration.
Answer:
The answer is (a.) An upward force balances the downward force gravity on the skydiver
The skydiver is falling at a constant velocity because the upward force is balancing the downward force of gravity. According to Newton, the opposite force balance each other. This is stated in Newton's second law of motion.
The statement that best applies Newton’s laws of motion to explain the skydiver’s motion is that An upward force balances the downward force of gravity on the skydiver.
Newton's 3rd law often applies to skydiving.
When gravity is not acting upon the skydivers they would continue moving in the direction the vehicle they jumped from was moving.
If no air resistance takes place, then the skydivers would still accelerating at 9.8 m/s until they hit the ground.
The skydiver after leaving the aircraft will accelerates downwards due to the force of gravity
usually as there is no air resistance acting in the upwards direction, and there is a resultant force acting downwards, the skydiver will accelerates towards the ground.
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A 4.00-m long rod is hinged at one end. The rod is initially held in the horizontal position, and then released as the free end is allowed to fall. What is the angular acceleration as it is released
Answer:
The angular acceleration α = 14.7 rad/s²
Explanation:
The torque on the rod τ = Iα where I = moment of inertia of rod = mL²/12 where m =mass of rod and L = length of rod = 4.00 m. α = angular acceleration of rod
Also, τ = Wr where W = weight of rod = mg and r = center of mass of rod = L/2.
So Iα = Wr
Substituting the value of the variables, we have
mL²α/12 = mgL/2
Simplifying by dividing through by mL, we have
mL²α/12mL = mgL/2mL
Lα/12 = g/2
multiplying both sides by 12, we have
Lα/12 × 12 = g/2 × 12
αL = 6g
α = 6g/L
α = 6 × 9.8 m/s² ÷ 4.00 m
α = 58.8 m/s² ÷ 4.00 m
α = 14.7 rad/s²
So, the angular acceleration α = 14.7 rad/s²
The pH scale is used to tell if a substance
is an acid or base. Substances with a pH
of 7 are neutral. An acid is anything
below 7 and a base is anything above 7.
Bleach has a pH of about 12. What type of
substance is bleach?
A. base
B. acid
C. neutral
Answer: Bleach is a base
Explanation: If bleach had a pH level of 12, a number above 7, than it is a base. Hope this helps!
Astronauts train for space flight in a centrifuge,which consists of a rotating arm with a cab at the outer end of thearm. The arm, which has a length of 58 feet, is revolved about thecenter of the centrifuge. An astronaut sits in the cab, which is thenrotated 50 times per minute. To the nearest hundred feet, how fardoes the astronaut travel in one minute?
Explanation:
We know that,
[tex]v = rw[/tex]
Where, v = tangential velocity (m/sec)
r = radius = 17.67 m
w = angular velocity = 0.83 revs/ sec
v = 14.66 m/sec
Distance in one minute = 879.6 m
= 2885.82 feet
An average family of four uses roughly 1200 Liters of water per day (1L. - 1000 cm3). A lake that covers 50 km² with a uniform depth and
supplies water to a local town with a population of 40,000 people would lose depth every year due to water consumption form
the locals, Ignore evaporation, rain, creeks and rivers.
Answer:
#_total = 4.38 10⁹ liter
Explanation:
For this exercise we can use a direct proportion rule (rule of three). If 4 people use 1200 liters how much water 1 person consumes
#_water = 1 person (1200 liter / 4 person)
#water = 300 liters
Now we look for the consumption of this person in a year, if 1 person consumes 300 liters 1 day, how many liters they consume in a year (365 days)
#_water_person_total = 365 days (300 liters / 1 day)
#_water_person_total = 109500 liters
This is the water consumption of 1 person in a year, the total of 40000 people how much they consume
#_total = 40000 person (109500 liter / 1 person)
#_total = 4.38 10⁹ liter
How is heat transferred during thermal conduction? Through direct contact of particles Through electromagnetic waves Through motion of hot and cold liquid Through the rising of a warm gas
Answer:
Through direct contact of particlesExplanation:
Heat is transferred in the following ways listed below
1. Conduction(Through direct contact of particles )
2. Convection(Through motion of hot and cold liquid )
3. Radiation(Through electromagnetic waves Through the rising of a warm gas )
1. Conduction: This has to do with the transfer of heat from one medium to another having direct contact with each other, the medium can either be solid or liquids
2. Convection: Has to do with the transfer of heat energy via molecules of the liquids in motion with different or varying temperature gradients
3. Radiation: Mostly occurs in gases, it is the transfer of energy through waves
A 250 watt electric bulb is lighted for 5 hours daily and four 6 watt bulbs are lighted for 4.5 hours daily. Calculate the energy consumed (in kWh) in the month of February.
Answer:
38.024 KWh
Explanation
250 watts multiplied with 5 hours daily multiplied with 28 days monthly equals 35000 Watt hours. Divided by a 1000 to get the KWh equals 35 KWh.
= 250×5hrs× 28days
= 35000watts
= 35000/1000
= 35KWh
Four 6 watt lightbulbs equals 24 watts 4x6=24
Hence, 24×4.5hrs×30days
= 3024watts
= 3024/1000
= 3.024KWhr
The total amount of energy consumed in the month of February = 35 KWh + 3.024 KWh = 38.024 KWh
Note that I had to use 28days since we are considering the month of February.
If 5 complete oscillations of a sound wave pass through a point in 0.5 s and the speed of sound was recorded to be 10 m/s, then find the wavelength of the sound.
Answer:
Wavelength = 1 meters
Explanation:
Given that,
Number of oscillations is 5
It passes through a point in 0.5 s
The speed of sound was recorded to be 10 m/s.
We need to find the wavelength of the sound.
Firstly, we will find frequency of this wave. Total no of oscillations per unit time is called frequency. So,
[tex]f=\dfrac{5}{0.5}\\\\f=10\ Hz[/tex]
Now the speed of wave in terms of wavelength and frequency is given by :
[tex]v=f\lambda[/tex]
Here, [tex]\lambda[/tex] = wavelength
[tex]\lambda=\dfrac{v}{f}\\\\\lambda=\dfrac{10\ m/s}{10\ Hz}\\\\\lambda=1\ m[/tex]
So, the wavelength of the sound is 1 meters.
If a falling object is covering 50 metre distance in 5 seconds, how much time it will take to cover 72 metres?
Answer:
7.2 seconds
Explanation:
50=5
72=t, criss-cross, t=72 (5)/50
A control clinic offers a program that guarantees a weight loss of up to 0.46 kg in one week. Express the weight loss in a ratio of milligrams per second.
Answer:
0.76 mg/s
Explanation:
0.46 kg/week × (1 week / 7 days) × (1 day / 24 hrs) × (1 hr / 3600 s) × (1000 g/kg) × (1000 mg/g) = 0.76 mg/s
Which statement about the dark nebulae is true? Group of answer choices They can be penetrated only with longer wavelengths such as radio and infrared. They block the vast majority of radio waves from our Galaxy. Hydrogen and helium are the chief absorbing and scattering agents. They can be penetrated only with shorter waves, such as UV and x-ray. Only one is known to exist.
Answer:
They can be penetrated only with longer wavelengths such as radio and infrared.
Explanation:
A dark nebula can be defined as an interstellar cloud that is so dense as a result of high concentration of gas and dust and as such it obscures the visible wavelengths of light from stars behind it, thus appearing completely opaque (dark patch) in front of a bright emission nebula or in regions having plenty stars.
Hence, dark nebulae can be penetrated only with longer wavelengths such as radio and infrared light because they cannot be absorbed by the dust layers or particles coated with frozen carbon monoxide and nitrogen residing in the dark nebulae.
claculate the pressure exerted by the water on the bottom of a deep dam of 12m from its surface .(density of water =1000kg/m sqare)
Explanation:
We know that,
[tex]hydrostatic \: pressure (p) = \alpha hg [/tex]
Where,
[tex] \alpha = density \: of \: water \: = 1000[/tex]
h = Height at which pressure is to be calculated
[tex]p = 1000 \times 12 \times 9.8 = 117600 \: [/tex]
Helpppp!!!ASAP!! THANK YOUUUU!
Answer:
F = 9.675Hz
Explanation:
pls for certain reasons let us make
wavelength = $frequency = FV = velocity3 loops : 6$/4 = L
6$/4 = 2
$ = 4/3 = 1.333
V = F x $
F = V/$
F = 12.9/1.333 = 9.675Hz
F = 9.675Hz
How large is theta? Please help!!!!
Answer:
30°
Explanation:
The angle between the normal and the vertical is the same as the angle between the incline and the horizontal. We can show this with geometry.
A 26-foot ladder is placed against a wall. If the top of the ladder is sliding down the wall at -2 feet per second (note that the rate is negative because the height is decreasing). At what rate is the bottom of the ladder moving away from the wall when the bottom of the ladder is 10 feet away from the wall?
Answer:
Dx/dt = 4,8 f/s
Explanation:
The ladder placed against a wall, and the ground formed a right triangle
with x and h the legs and L the hypothenuse
Then
L² = x² + h² (1)
L = 26 f
Taking differentials on both sides of the equation we get
0 = 2x Dx/dt + 2h Dh/dt (1)
In this equation
x = 10 distance between the bottom of the ladder and the when we need to find, the rate of the ladder moving away from the wall
Dx/dt is the rate we are looking for
h = ? The height of the ladder when x = 10
As L² = x² + h²
h² = L² - x²
h² = (26)² - (10)²
h² = 676 - 100
h² = 576
h = 24 f
Then equation (1)
0 = 2x Dx/dt + 2h Dh/dt
2xDx/dt = - 2h Dh/dt
10 Dx/dt = - 24 ( -2 ) ( Note the movement of the ladder is downwards)
Dx/dt = 48/10
Dx/dt = 4,8 f/s
1.A particle is moving up an inclined plane. Its velocity changes from 15m/s to 10m/s in two seconds. What is its acceleration? *
[tex] \huge{ \underline{ \boxed{ \bf{ \blue{Solution:}}}}}[/tex]
Provided:-Initial velocity = 15 m/sFinal velocity = 10 m/sTime taken = 2 sTo FinD:-Accleration of the particle....?How to solve?We will solve the above Question by using equations of motion that are:-
v = u + ats = ut + 1/2 at²v² = u² + 2asHere,
v = Final velocity u = Initial velocity a = acceleration t = time taken s = distance travelled Work out:By using first equation of motion,
⇛ v = u + at
⇛ 10 = 15 + a(2)
⇛ -5 = 2a
Flipping it,
⇛ 2a = -5
⇛ a = -2.5 m/s² [ANSWER]
❍ Acclearation is negative because final velocity is less than Initial velocity.
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help me pleaseeeeeeddd
Answer:
Explanation:
a )
According to graph the object moves with constant velocity of 10 m /s during first 8 s and then its velocity changes to - 5 m /s from 8 th second upto 12 th second .
Initial displacement = 8 m
displacement during 8 s = velocity x time
= 8 x 10 = 80 m
total displacement = 88 m
b )
displacement during period from 8 th to 12 th s
= - 5 x 4 = - 20 m
total displacement after 12 s
= 88 - 20 = 68 m
c ) average speed = total distance covered during 12 s / total time
= (80 + 20) / 12
= 8.33 m /s
average velocity = total displacement during 12 s / total time
= 80 - 20 / 12
= 60 / 12
= 5 m /s .
to what temperature must a given mass of nitrogen at zero degrees be heated so both its volume and pressure will be doubled
Answer:
0 degrees Celsius is 273 degrees Kelvin. As both pressure and volume are proportional to absolute temperature, in order to double both you would need to quadruple the temperature. I.e. 273 X 4 = 1092 Kelvin = 819 Celsius
Explanation:
Jaiden is writing a report about the structure of the atom in her report,she says that the atom has three main parts and two subatomic particles. Do you agree with her?why or why not
Answer:
I do not agree with the answer.
Because in reality, the atom has 2 main parts and 3 subatomic particles.
Explanation:
The parts of an atom are:
- The crust: It is the outer part of the atom and is the place where the electrons are.
- The nucleus: It is the central part of the atom and is the place that contains the protons and neutrons.
The subatomic particles of the atom are:
- Electrons: They are negatively charged particles that go in the atom's crust and are divided into specific sections.
- Protons: They are particles with a positive electric charge, the number of protons in the nucleus of an atom is what determines the atomic number of an element.
- Neutrons: They are atoms with no electric charge.
. Mass of a man is 40 kg. find his weight (g=9.8 m/s?)
Answer: 392N
Explanation: W=mg
W= 40x9.8
= 392N
Answer:
[tex]\large \boxed{\sf 392.4 \ N}[/tex]
Explanation:
[tex]\sf Weight \ (N) =mass \ (kg) \times acceleration \ of \ gravity \ (m/s^2)[/tex]
[tex]W=mg[/tex]
[tex]W=40 \times 9.81[/tex]
[tex]W= 392.4[/tex]
prove that..
please help
[tex] \large{ \boxed{ \bf{ \color{red}{Universal \: law \: of \: gravitation}}}}[/tex]
Every object in the universe attracts every other object with a force which is proportional to the product of their masses and inversely proportional to the square of the distance between them. The forces along the line joining the centre of the two objects.
❍ Let us consider two masses m1 and m2 line at a separation distance d. Let the force of attraction between the two objects be F.
According to universal law of gravitation,
[tex] \large{ \longrightarrow{ \rm{F \propto m_1 m_2}}}[/tex]
Also,
[tex] \large{ \longrightarrow{ \rm{ F \propto \dfrac{1}{ {d}^{2} } }}}[/tex]
Combining both, We will get
[tex] \large{ \longrightarrow{ \rm{F \propto \dfrac{ m_1 m_2}{ {d}^{2}}}}} [/tex]
Or, We can write it as,
[tex] \large{ \longrightarrow{ \rm{F \propto \: G \dfrac{ m_1 m_2}{ {d}^{2} }}}}[/tex]
Where, G is the constant of proportionality and it is called 'Universal Gravitational constant'.
☯️ Hence, derived !!
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What are three different types of electromagnetic radiation that you use in your everyday life? Be sure to identify the source of the radiation as well as the type of electromagnetic radiation that is used.
Explanation:
Some Uses of Electromagnetic waves :
(A) Microwaves
Satellite CommunicationFor cooking food, etc(B) X - Rays (produced by slowing fast moving electrons)
Used in diagnosis of bones, etcluggage content search at airport, etc(C) Radio Waves
Radio and television broadcasting Navigational communication, etcBus starts from rest if the acceleration of the bus is 0.5 MS squared what will be the velocity at the end of two minutes and what distance will it cover during that time
Explanation:
Given that,
Initial speed of the bus, u = 0
Acceleration of the bus, a = 0.5 m/s²
Let v is the velocity at the end of 2 minutes. The change in velocity divided by time equals acceleration.
So,
[tex]a=\dfrac{v-u}{t}\\\\v=u+at\\\\v=0+0.5\times 120\\\\v=60\ m/s[/tex]
Let d is the distance cover during that time. So,
[tex]v^2-u^2=2ad\\\\d=\dfrac{v^2-u^2}{2a}\\\\d=\dfrac{(60)^2}{2\times 0.5}\\\\d=3600\ m[/tex]
So, the final speed is 60 m/s and the distance covered during that time is 3600 m.
