The half-life of a substance is 10 years. What percent of the substance remains after 2 half-lives.

need answer asap. i think its 2.5 but not sure

Answers

Answer 1

Answer:

i think its 2.5 as well

Explanation:


Related Questions

Rain drops are formed when water vapor _____.

condenses on grass
evaporates
condenses on dust
freezes

Answers

Answer:

Condenses on dust

Explanation:

Pls brainiest

Answer:

condenses on dust

Explanation:

A flat loop of wire consisting of a single turn of cross-sectional area 8.00 cm2 is perpendicular to a magnetic field that increases uniformly in magnitude from 0.500 G to 1.60 M in 0.99 s. What is the resulting induced current if the loop has a resistance of 1.20 Ω?

Answers

Complete Question

A flat loop of wire consisting of a single turn of cross-sectional area 8.00 cm2 is perpendicular to a magnetic field that increases uniformly in magnitude from 0.500 T to 1.60 T in 0.99 s. What is the resulting induced current if the loop has a resistance of [tex]1.20 \ \Omega[/tex]

Answer:

The current is   [tex]I = 0.0007 41 \ A[/tex]

Explanation:

From the question we are told that

   The  area is  [tex]A = 8.00 \ cm^2 = 8.0 *10^{-4} \ m^2[/tex]

   The initial magnetic field at [tex]t_o = 0 \ seconds[/tex]  is [tex]B_i = 0.500 \ T[/tex]

   The magnetic field at [tex]t_1 = 0.99 \ seconds[/tex] is  [tex]B_f = 1.60 \ T[/tex]

     The resistance is  [tex]R = 1.20 \ \Omega[/tex]

Generally the induced emf is mathematically represented as

      [tex]\epsilon = A * \frac{B_f - B_i }{ t_f - t_o }[/tex]

=>   [tex]\epsilon = 8.0 *10^{-4} * \frac{1.60 - 0.500 }{ 0.99- 0 }[/tex]

=>   [tex]\epsilon = 0.000889 \ V[/tex]

Generally the current induced is mathematically represented as

     [tex]I = \frac{\epsilon}{R }[/tex]

=>  [tex]I = \frac{0.000889}{ 1.20 }[/tex]  

=>  [tex]I = 0.0007 41 \ A[/tex]  

The pharyngeal tonsil is found in the __________________________ .

Answers

Answer:

The pharyngeal tonsils are located near the opening of the nasal cavity into the pharynx. When these tonsils become enlarged they may interfere with breathing and are called adenoids.

Consider an underwater spherical air bubble (you can assume the index of refraction of air is 1 and water is 1.33) with radius R. This bubble can act as a lens. What is its focal length?

Answers

Answer:

-2R

Explanation:

The focal length can be calculated using this formula

1/f = (n1/n2-1)(1/r1-1/r2)

1/f = (1/1.33-1)(1/r + 1/r)

= -0.133/1.33(2/R)

F = -2R

The focal length is this

HELP!!
You are traveling at a speed of 70 miles per hour. How long did it take you to travel 2400 miles?

Answers

Answer:

So do 2400 divided by 70. I got 34.285714 and the numbers behind the decimal are repeating. If you round it you get 34.3

A 5 kg ball is moving at a velocity of +2 m/s when it
speeds up to +5 m/s in 7 seconds.
Calculate the acceleration.

Answers

Heya!!

For calculate aceleration, lets applicate formula:

                                                   [tex]\boxed{a=\frac{V-V_o}{t} }[/tex]

                                                   Δ   Being   Δ

                                          V = Final Velocity = 5 m/s

                                         Vo = Initial Velocity = 2 m/s

                                          a = Aceleration = ? m/s²

                                                   t = Time = 7 s

⇒ Let's replace according the formula:

[tex]\boxed{a=\frac{5\ m/s - 2 \ m/s}{7\ s} }[/tex]

⇒ Resolving

[tex]\boxed{ a=0,428\ m/s^{2}}[/tex]

Result:

The aceleration of the object is 0,428 m/s²

Good Luck!!

Answer:

Ksasdasd

Explanation:

To exercise, a man attaches a 4.0 kg weight to the heel of his foot. When his leg is stretched out before him, what is the torque exerted by the weight about his knee, 40 cm away from the weight? Use g = 10 m/s2. A. 160 Nâm B. 16 Nâm C. 1600 Nâm D. 1.6 Nâm

Answers

Answer:

B. τ = 16 Nm

Explanation:

In order to find the torque exerted by the weight attached to the heel of man's foot, when his leg is stretched out. We use following formula:

τ = Fd

here,

τ = Torque = ?

F = Force exerted by the weight = Weight = mg

F = mg = (4 kg)(10 m/s²) = 40 N

d = distance from knee to weight = 40 cm = 0.4 m

Therefore,

τ = (40 N)(0.4 m)

B. τ = 16 Nm

The torque exerted by the weight about his knee, 40 cm away from the weight is: D. 1.6 Nm

Given the following data:

Mass = 4.0 kgDistance = 40 cm to m = 0.04 metersAcceleration due to gravity (g) = 10 [tex]m/s^2[/tex].

To determine the torque exerted by the weight about his knee, 40 cm away from the weight:

First of all, we would calculate the force being exerted by the weight on his heel.

[tex]Force = mg\\\\Force = 4 \times 10[/tex]

Force = 40 Newton

Mathematically, torque is given by the formula:

[tex]Torque = force \times distance[/tex]

Substituting the given parameters into the formula, we have;

[tex]Torque = 40 \times 0.04[/tex]

Torque = 1.6 Nm

Read more: https://brainly.com/question/14703849

At what final position would you be if you began at initial position of 4m and drove at 30m/s for 20 seconds?

Answers

Answer:

604m

Explanation:

30 * 20=600

600 + 4 = 604m

A rock is thrown with an initial vertical velocity 50 m/s at an angle of 40 degrees.
a. What is the horizontal component of the velocity?
b. What is the vertical component of the velocity?
c. What is the hang timel?
d. What is the peak height?
e. What is the range?

Answers

Answer:

[tex]38.3\ \text{m/s}[/tex]

[tex]32.14\ \text{m/s}[/tex]

6.55 seconds

[tex]52.65\ \text{m}[/tex]

[tex]254.84\ \text{m}[/tex]

Explanation:

u = Initial velocity of rock = 50 m/s

[tex]\theta[/tex] = Angle of throw = [tex]40^{\circ}[/tex]

g = Acceleration due to gravity = [tex]9.81\ \text{m/s}^2[/tex]

Horizontal component is given by

[tex]u_x=u\cos\theta\\\Rightarrow u_x=50\times \cos40^{\circ}\\\Rightarrow u_x=38.3\ \text{m/s}[/tex]

The horizontal component of the velocity is [tex]38.3\ \text{m/s}[/tex]

Vertical component is given by

[tex]u_y=u\sin\theta\\\Rightarrow u_y=50\times \sin40^{\circ}\\\Rightarrow u_y=32.14\ \text{m/s}[/tex]

The horizontal component of the velocity is [tex]32.14\ \text{m/s}[/tex]

Time of flight is given by

[tex]t=\dfrac{2u\sin\theta}{g}\\\Rightarrow t=\dfrac{2\times 50\sin40^{\circ}}{9.81}\\\Rightarrow t=6.55\ \text{s}[/tex]

The hang time of the rock is 6.55 seconds

Maximum height is given by

[tex]h=\dfrac{u^2\sin^2\theta}{2g}\\\Rightarrow h=\dfrac{50^2\sin^240^{\circ}}{2\times 9.81}\\\Rightarrow h=52.65\ \text{m}[/tex]

Maximum height is [tex]52.65\ \text{m}[/tex]

Range is given by

[tex]d=\dfrac{u^2\sin2\theta}{g}\\\Rightarrow d=\dfrac{50^2\sin(2\times40)^{\circ}}{9.81}\\\Rightarrow d=254.84\ \text{m}[/tex]

The range is [tex]254.84\ \text{m}[/tex]

A 20.0 cm wrench is used to generate a torque at a bolt. A force of 50 N is applied at the end of the wrench at an angle of 60.0 degrees to the wrench. The torque generated at the bolt is A. 4.9 N•m. B. 5.7 N•m. C. 6.0 N•m. D. 7.5 N•m. E. 8.7 N•m.

Answers

Answer:

The correct option is  E

Explanation:

From the question we are told that

   The length of the wrench which is also the radius of the circle made by the wrench  is  [tex]l =r = 20.0 \ cm = 0.2 \ m[/tex]

   The force is  [tex]F = 50 \ N[/tex]

    The angle is  [tex]\theta = 60^o[/tex]

Generally the torque generated by the bolt is mathematically represented as

     [tex]\tau = F * sin (\theta ) * r[/tex]

=>  [tex]\tau = 50 * sin (60 ) * 0.2[/tex]

=>  [tex]\tau = 8.7 \ N \cdot m[/tex]

Rebecca heated 50mL of water from 0 degrees Celsius to 60 degrees Celsius. How much energy did she use to heat the water? Remember: cal=m*deltaT


(WRITE THE WORK!/Give explanation.)

Answers

Answer:

Q = 12540  J

Explanation:

It is given that,

Mass of water, m = 50 mL = 50 g

It is heated from 0 degrees Celsius to 60 degrees Celsius.

We need to find the energy required to heat the water. The formula use to find it as follows :

[tex]Q=mc\Delta T[/tex]

Where c is the specific heat of water, c = 4.18 J/g°C

Put all the values,

[tex]Q=50\times 4.18\times (60-0)\\Q=12540\ J[/tex]

So, 12540 J of energy is used to heat the water.

When the rate of the forward reaction equals the rate of the backward reaction, the system is said to be in

Answers

Answer:

equilibrium

Explanation:

bcoz forward reaction equals backward reaction

an explanation can be consistent but may not be the best explanation for a phenomenon

True

False

Answers

Answer:

true

Explanation:

i’m pretty sure it’s true

if it took 3.7 seconds for the sound to reach john how far away was the firework shell when it exploded in kilometers assume that the speed of sound in air is 1,236 km/h

Answers

Answer:

1.2703 km

Explanation:

The speed can be calculated using the formula;

Speed (m/s) = distance (m) ÷ time (s)

Based on the information in this question, it took 3.7 seconds for a sound with speed of 1236 km/h to reach John. The distance will be:

Distance = speed × time

However, we need to convert the time in seconds (s) to hour (hr).

1 second = 0.000277778 hour

3.7 seconds = 0.00102778 hours.

Hence,

distance = 1236 × 0.00102778

Distance = 1.2703 km

All of the following are categories used to classify problems except problems of
A. arrangement
B. inducing structure
C. transformation
D. schematic completion

Answers

Answer:D. schematic completion

Explanation:The rest are actual categoroes

Answer:

schematic completion

Explanation:

got it right on edge

Emmett is lifting a box vertically. Which forces are necessary for calculating the total force?

Fp, Ff, and Fg
Fp and FN
Fp, Fg, and Ff
Fp and Fg

Answers

Answer:

Answer is D: D.Fp and Fg

Explanation:

I did the quiz some time ago and rember it hope it helps.

Answer:

i just finish its d

Explanation:

A tennis rackets delivers 500 N on impact with a tennis ball. What is the force of the tennis ball on the racket?
A: this cannot be determined without knowing the mass of the tennis ball
B: the force on the tennis racket is more than 500 N
C: the force on the tennis racket is 500 N
D: the force on the tennis racket is less than 500 N

Answers

Answer:

the a.

Explanation:

because if you compute you can't know the distance


Rebecca heated 50mL of water from 0 degrees Celsius to 60 degrees Celsius. How much energy did she use to heat the water? Remember: cal=m*deltaT


(WRITE THE WORK!/Give explanation.)

I’ll give BRAINLIEST.

Answers

Answer:

12552 J or 3000 calories

Explanation:

Q = m × c × ∆T

Where;

Q = amount of heat energy (J)

m = mass of water (g)

c = specific heat capacity (4.184 J/g°C)

∆T = change in temperature

For 50mL of water, there are 50g, hence, m = 50g, c = 4.184 J/g°C, initial temperature = 0°C, final temperature = 60°C.

Q = m × c × ∆T

Q = 50 × 4.184 × (60 - 0)

Q = 209.2 × 60

Q = 12552 J

Hence, the amount of heat energy used to heat the water is 12552 J or 3000 calories

Calculate the wavelengths of a 1530 kHz AM radio signal, a 105.1 MHz FM radio signal, and a 1.90 GHz cell phone signal.

Answers

Answer:

196.07 m, 2.85 m and 0.15 m

Explanation:

Frequency of AM radio signal, f₁ = 1530 kHz

Its wavelength can be given by :

[tex]\lambda_1=\dfrac{c}{f_1}\\\\=\dfrac{3\times 10^8}{1530\times 10^3}\\\\=196.07\ m[/tex]

Frequency of FM radio signal, f₂ = 105.1 MHz

Its wavelength can be given by :

[tex]\lambda_2=\dfrac{c}{f_2}\\\\=\dfrac{3\times 10^8}{105.1\times 10^6}\\\\=2.85\ m[/tex]

Frequency of cell phone signal, f₃ = 1.9 GHz

Its wavelength can be given by :

[tex]\lambda_2=\dfrac{c}{f_2}\\\\=\dfrac{3\times 10^8}{1.9\times 10^9}\\\\=0.15\ m[/tex]

Hence, the required wavelengths are 196.07 m, 2.85 m and 0.15 m respectively.

How are all paths that have a displacement of zero similar?

Answers

Answer:

Any situation that has a path that stops at the same position that it started from has a displacement of zero

Explanation:

hope it helps

Find the magnitude of the buoyant force on the block. The acceleration of gravity is 9.8 m/s 2 . Answer in units of N.

Answers

The answer is 2248.02 N.

An engineer is designing a runway for an airport. Of the planes that will use the airport, the
lowest acceleration rate is likely to be 3 m/s2
. The takeoff speed for this plane will be 70 m/s.
Assuming this minimum acceleration, what is the minimum allowed length for the runway?

Answers

Answer:

816m

Explanation:

70^2m/s=2(3m/ss)(x)

x=816

7.
As the distance from the Sun increases the time to orbit the Sun
a. Increases
b. Decreases
c. Stays the same

Answers

As the distance from the Sun increases the time to orbit the Sun  increases. (a)

Examples:

-- Nearest planet to the sun: Mercury.  Time to orbit the sun: 88 days

-- 3rd planet from the sun:  Earth.  Time to orbit the sun: 1 year

-- 5th planet from the sun:  Jupiter.  Time to orbit the sun: 12 years

-- 9th closest object to the sun:  Pluto.  Time to orbit the sun: 248 years

Another pair of examples:

-- Object in a near Earth orbit:  International Space Station

Time to orbit the Earth:  90 minutes

-- Object in a far Earth orbit:  the Moon

Time to orbit the Earth:  27.3 days

The reason for all of this is:  Two things about orbits.

1).  The larger the orbit is, the farther the object has to travel around it.

2).  The farther out the object is, the slower it travels in its orbit.

This is simply the way gravity works.

Most generation of electricity involves turning turbines to spin coils of metal. However some do not. Give a type of energy that does not involve spinning coils of metal. How does it generate electricity?

Answers

Answer:

Photovoltaic Energy

Explanation:

There are other forms of energy that do not involve spinning of metals to generate electricity, one of many such is the Solar Photovoltaic Energy.

Photovoltaic is a form of energy in which sunlight Is directly into electricity. This type of energy is often used to power devices such as small wrist watches, rechargeable lamps, and others. They are connected together to panels that are joined together in arrays to power people or heavy power plants. Photovoltaic power plants are happening to be one of the fastest growing sources of electricity generation around the world.

What is energy?

A. A change that appears in an object when forced is applied.
B. The property of a body that gives it mess.
C. The amount of heat produced by the body.
D. The ability of an object to undergo change.
E. The ability of a body to move.

Answers

Answer:

A

Explanation:

Answer: a or e

Explanation:

if you double the magnitude of a vector, does it follow that the magnitude of the components double? Give example.

Answers

Answer:

The magnitude of the vector clearly doubles if each of its components is doubled.

Explanation:

A 4 kilogram box is at rest on a frictionless floor. A net force of 12 newtons acts on it. What is the acceleration of the box?

Answers

Answer:

3 m/s^2

Explanation:

Step one:

given

Mass m= 4kg

Force F= 12N

Required

Acceleration the relation between force, acceleration, and mass is Newton's first equation of motion, which says a body will continue to be at rest or uniform motion unless acted upon by an external force

F=ma

a=F/m

a=12/4

a=3 m/s^2

help asap
How does the scientist know that the substance goes through a change of state during the time period labeled B on the graph?
a.the temperature remains the same
b.the temperature increases gradually
c.the particles start slowing down
d.the particles start moving faster

Answers

Answer:

The answer is A. The temperature remains the same.

A volume of air increases 0.227 m^3 at a net pressure of 2.07 x 10^7 Pa. How much work is done on the air?

Answers

Answer:

The work done on the air is 4.699 x 10⁶ Joules

Explanation:

Given;

increase in air volume, ΔV = 0.227 m³

net pressure of the air, P = 2.07 x 10⁷ Pa

The work done on the air is given by;

W = PΔV

Where;

W is the work done on the air

P is the net pressure

ΔV  is the increase in air volume

Substitute the given values and solve for work done;

W = (2.07 x 10⁷ Pa) (0.227 m³)

W = 4.699 x 10⁶ Joules

Therefore, the work done on the air is 4.699 x 10⁶ Joules

Integrated Concepts A lightning bolt strikes a tree, moving 20.0 C of charge through a potential difference of 1.00×102 MV . (a) What energy was dissipated? (b) What mass of water could be raised from 15ºC to the boiling point and then boiled by this energy? (c) Discuss the damage that could be caused to the tree by the expansion of the boiling steam.

Answers

Answer:

a) 2*10^9 J

b) 764.8 kg

Explanation:

Given that

Energy of charge, q = 20 C

Potential difference, ΔV = 1*10^2 MV = 1*10^2 * 10^6 V = 1*10^8 V

a)

To find the energy dissipated, we use the formula

ΔU = qΔV

ΔU = 20 * 1*10^8

ΔU = 2*10^9 J

b)

Change in temperature, ΔT = 100 - 15°

ΔT = 85° C

Change in energy, ΔU = 2*10^9 J

Specific heat of water, C = 4180 j./Kg.K

Latent heat of vaporization, L(v) = 2.26*10^6 J/Kg

Q1 = mcΔT

Q2 = mL(v)

Net energy needed, U = Q1 + Q2

U = mcΔT + mL(v)

U = m (cΔT + L(v))

m = U /[cΔT + L(v)]

Being that we have all the values, we then substitute

m = 2*10^9 / [(4180 * 85) + 2.26*10^6]

m = 2*10^9 / (3.553*10^5 + 2.26*10^6]

m = 2*10^9 / 2.615*10^6

m = 764.8 kg

c)

Having 765 kg of steam at the temperature would have extreme effect on the tree, damaging it permanently. Possibly even blowing it to pieces

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