Exercise Book: 18
A piece of
radioactive material contains
2000 atoms. If its half life is 20 seconds
the time take for 125 atoms to remain is?

Answers

Answer 1
Liza Liza pizza dinner

Related Questions

What is the wavelength of a wave?

Answers

Definition: Wavelength can be defined as the distance between two successive crests or troughs of a wave.

how does light spectra help us understand astronomy

Answers

Answer: From spectral lines astronomers can determine not only the element, but the temperature and density of that element in the star.

Explanation: The spectral line also can tell us about any magnetic field of the star. The light from the stuff between the stars allows astronomers to study the interstellar medium.

Hope this helps! :)

Sarah was trying to explain electromagnetic waves energy to her lab partner. She said that microwaves have more energy than infrared
waves. Her partner Jose argued that infrared waves have more energy Who is right and provides the correct justification?
A Jose is correct because infrared waves have a smaller amplitude than microwaves
B. Jose is correct because infrared waves have a greater frequency than microwaves.
C. Sarah is correct because microwaves have a greater frequency than infrared.
Sarah is correct because microwaves have a smaller wavelength than infrared.

Answers

Ndjdjdm g t yheisbs msid su T❤️‍♀️b?.): dh dur rjruviz

A. Jose is correct because infrared waves have a smaller amplitude than microwaves

Which three statements could explain the increase in the deer population? A. Rainfall was above average over the past five years B. A hawk species settled into the area five years ago C. Extremely harsh winters occurred during the past five years D. The number of cattle ranchers decreased in the past five years E. The law allowed an extended wolf hunting season for the past five years

Answers

Answer:

D. The number of cattle ranchers decreased in the past five years

Explanation:

According to Jennifer M Schieltz and Daniel I Rubenstein (2016), "More than a quarter of earth's land surface is used for grazing domestic livestock." This has negative effects on availability of pasture for herbivorous wildlife such as the deer.

Increase in the number of cattle  ranchers decreases the availability of pasture and vice versa.

Hence, the decrease in the number of cattle ranchers over the past five years led to an increase in the deer population due to a decrease in competition for pasture.

help me plz Your starting fitness level is known as__________. (10 points) a starting point b beginning level c baseline d entry level

Answers

Answer:

Would it be starting point?

Explanation:

When you start a sport or something, you may not be good or bad at it. However, as time goes on you are going to improve.

Idk if this helps or not buh yeah

A truck heading east has an initial velocity of 6 m/s. It accelerates at 2 m/s2 for 12 seconds. What distance does the truck travel in the given time?

84 m
144 m
216 m
360 m

Answers

The answer (distance) is:

216m

The distance of the truck in the given time is 216 m.

How do you find displacement with velocity and acceleration?

Displacement (s) of an object equals, velocity (u) times time (t), plus ½ times acceleration (a) times time squared (t2). Use standard gravity, a = 9.80665 m/s2, for equations involving the Earth's gravitational force as the acceleration rate of an object.

How do you find velocity from acceleration?

Multiply the acceleration by time to obtain the velocity change: velocity change = 6.95 * 4 = 27.8 m/s . Since the initial velocity was zero, the final velocity is equal to the change in speed. You can convert units to km/h by multiplying the result by 3.6: 27.8 * 3.6 ≈ 100 km/h.

Learn more about velocity from acceleration here: brainly.com/question/14344386

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How would YOU define speed?

Answers

Speed is a scalar quantity that refers to “how fast an object is moving.”

Answer:

Speed is a way of measuring how quickly something is moving or being done, or something moving fast. An example of speed is a car being driven 45 miles per hour. An example of speed is someone cleaning a room in 10 minutes.

Lily takes 3 hours to travel from place A to place B at the rate of 60 miles per hour . She takes 2 hours to travel from B to c with50% increased speed .find the average speed from place A to C

Answers

Answer:

The average speed form A to C is 72 miles/hour

Explanation:

Average Speed

If an object travels a distance d in a time t regardless of the direction, the average speed is the quotient of the distance over the time:

[tex]\displaystyle \bar v=\frac{d}{t}[/tex]

Lily travels from A to C in two steps:

First, she takes ta=3 hours from A to B at va=60 miles/hour. The distance traveled in that time is:

da=va*ta

da=3*60 = 180

da = 180 miles

Then she takes tb=2 hours to travel from B to C at a speed 50% increased with respect to va, thus:

vb=150*va/100=1.5*60=90

vb=90 miles/hour

She travels a distance:

db=2*90=180 miles

The total distance traveled is

dt=180 + 180 = 360 miles

And the total time taken is

tt= 3 + 2 = 5 hours

Thus, the average speed is:

[tex]\displaystyle \bar v=\frac{dt}{tt}[/tex]

[tex]\displaystyle \bar v=\frac{360}{5}[/tex]

[tex]\displaystyle \bar v=72\ miles/hour[/tex]

The average speed form A to C is 72 miles/hour

how are open and closed systems related to energy?

Answers

Answer:

The stovetop system is open because heat can be lost into the air. A closed system is one that cannot transfer energy to its surroundings.

What is one difference between an electromagnetic wave and a mechanical wave?

A.
A mechanical wave can travel through a vacuum. An electromagnetic wave must have a medium to travel through.

B.
An electromagnetic wave can travel through a vacuum. A mechanical wave must have a medium to travel through.

C.
An electromagnetic wave moves parallel to the direction of the wave's travel. A mechanical wave can move only perpendicular to the direction of the wave's travel.

D.
An electromagnetic wave moves perpendicular to the direction of the wave's travel. A mechanical wave can move only parallel to the direction of the wave's travel.

Answers


B.
An electromagnetic wave can travel through a vacuum. A mechanical wave must have a medium to travel through.

The answer is b

an object near the surface of a planet falls 54m in 3s. what is the acceleration due to gravity on that planet

Answers

Answer:

12s

Explanation:

Giwe two Escample of translucent
Object​

Answers

Answer: Butter paper, ground glass, and a bonus thin sheets of plastic

Explanation: Translucent objects allow light to pass through them partially.

Answer:

Tinted windows, frosted glass, sunglasses, wax paper, fingers, and certain plastics are all examples of translucent objects. Translucent is defined as a material that blurs light as it passes through.

Hope this helps :)

How do you measure the weigh of an object

Answers

Answer: Weight is a measure of the force of gravity pulling down on an object. It depends on the object's mass and the acceleration due to gravity, which is 9.8 m/s2 on Earth. The formula for calculating weight is F = m × 9.8 m/s2, where F is the object's weight in Newtons (N) and m is the object's mass in kilograms.

Answer:gravity pulling down on an object

Explanation:

Find the momentum
of a
30g ball traveling
12 m/s

Answers

Answer:

0.36 kgm/s

Explanation:

Formula for momentum is :

P=mv

p is momentum

m is mass = 30g = 0.03kg

v is velocity = 12 m/s

P= 0.03 x 12

P = 0.36 kgm/s

A fish is swimming around the 720-meter perimeter of her pond. If she swims 10 laps in 120 minutes, what is her average speed in m/min

Answers

Answer:

60

Explanation:

Her average speed is 60 m/min

1. If a plane flying at 230 m/s drops a package to the ground 75m below.
a. How much time before the package hits the ground?
b. How far in the x-direction does the package travel before it hits the ground?
c. What is the speed and direction of the package before it hits the ground?

2. A diver runs with a speed of 1.2 m/s straight off a diving board 10m above the water.
a. How much time is he in the air?
b. How far from the board does he land?
c. What is his speed right before he strikes the water?

3. A car leaves the edge of a cliff 55m high and hits 130 m from the base.
a. How much time is the car in the air?
b. What is the initial velocity of the car?
c. What is the speed and direction it hits the ground?

Answers

Answer:

What class is this for, I think I have done this before.

PLZ HELP!

The image here shows four soccer balls at four different locations on an uneven soccer field very near sea level. Which soccer ball has the greatest amount of potential energy?


Ball B
Ball C
Ball A
Ball D

Answers

Answer:

The answer is B.

Explanation:

Because that's the one that's more-so higher up than the other soccer balls. This grants the ball to have higher potential energy than the rest.

Quote:

"Your body is as weak as your soul, so it is easy to separate the two."

- Akuma

The ball b would have the greatest amount of the potential energy as the mass of each ball is the same then the ball on the highest altitude would have the greatest amount of the potential energy contained with it.

What is mechanical energy?

Mechanical energy is the combination of all the energy in motion represented by total kinetic energy and the total stored energy in the system which is represented by total potential energy.

The mechanical energy = potential energy + kinetic energy

As given in the problem, the image here shows four soccer balls at four different locations on an uneven soccer field very near sea level.

The potential energy of the ball = mass×gravity×height

Since each ball's mass is the same, the ball at the highest altitude would have the most potential energy within it. As a result, ball b would have the greatest quantity of potential energy.

Thus,the correct answer is option A.

Learn more about mechanical energy from here, refer to the link;

brainly.com/question/12319302

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The diagram shows a hand reaching for a doorknob.
Which action would decrease the strength of the electric force between the hand and the doorknob?
A) moving the hand closer to the doorknob
B) moving the hand farther away from the doorknob
C) adding negative charges to the hand
D) magnetizing the doorknob

Answers

Answer: Moving the hand farther away from the door knob

Explanation:

The magnetic force becomes weaker when there is more distance

The magnetic force becomes weaker when there is more distance.

What is Electric force?

The nucleus and electrons are drawn to one another by the electric force. The void created by a positive or negative charge is referred to as an electric field since it generates a field there.

If you had a positive charge just here, it would have an electric field surrounding it and affect the area in which it was located.

The same applies for a negative charge; it too has an electric field surrounding it. Now, opposite charges attract each other while like charges repel one another. A positive charge here and a positive charge here, for example, would resist one another since they are similar charges.

Therefore, The magnetic force becomes weaker when there is more distance.

To learn more about Magnetic force, refer to the link:

https://brainly.com/question/3160109

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A cannonball is launched off a 100 m cliff horizontally with an initial velocity of 50 m/s. The goal is to have the cannonball travel a target distance of 400m. Based on this, will the cannonball reach the target distance?

A. Yes, the cannonball will hit its goal
B. More information is needed to determine the outcome
C. No, the cannonball will overshoot its goal
D. No, the cannonball will fall short of the goal

self note *9

Answers

Answer:

D. No, the cannonball will fall short of the goal

Explanation:

Based on the information given in the problem,  No, the cannonball will fall short of the goal, therefore the correct answer is option D.

What are the three equations of motion?

There are three equations of motion given by Newton,

v = u + at

S = ut + 1/2×a×t²

v² - u² = 2×a×s

As given in the problem a  cannonball is launched off a 100 m cliff horizontally with an initial velocity of 50 m/s. The goal is to have the cannonball travel a target distance of 400 meters,

By using the second equation of motion in the vertical direction,

100 = ut + 0.5*9.81*t²

t = 4.51 seconds

The distance traveled by the cannonball in the horizontal direction at the same time = 4.51*50

                 =205 meters

Thus, based on the information given in the problem,  No, the cannonball will fall short of the goal, therefore the correct answer is option D.

To learn more about equations of motion here, refer to the link;

brainly.com/question/5955789

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The distance is 10 meters. What is the variable?

Answers

The distance between two points needs to be measured, in meters. The true distance
between the points is 10 meters, but due to measurement error we can’t measure the
distance exactly. Instead, we will observe a value of 10+ϵ
ϵ, where the error ϵ
ϵ is distributed
(0,0.04)
N(0,0.04). Find the probability that the observed distance is within 0.4 meters of the
true distance (10 meters). Give both an exact answer in terms of Φ
Φ and an approximate
numerical answer.

3. A cat is moving at 18 m/s when it accelerates at 4 m/s2 for 2 seconds. What is
his new velocity?

Answers

Answer:

v=u+at

v=8+(4x2)

v=16m\s2

Five 6 ohm resistors are connected in parallel. Which of the following is their effective resistance?

A. 6 ohm​​
B. 1.2 ohm​​
C. 30 ohm​​
D. 5/6 ohm

Answers

1/Rt = 1/R1 + 1/R2 + 1/R3+ 1/R4+ 1/R5

1/Rt = 1/6+ 1/6+1/6+1/6+1/6

1/Rt = 5/6

Rt = 6/5

Rt = 1.2 ohm

so B is the answer

PLEASE HELP ME!!!

Which of the following connect to the energy conversions that happen when you plug a vacuum into an electrical outlet and turn it on?

A.)kinetic, chemical, sound
B.)sound, nuclear, electrical
C.)chemical, nuclear, electrical
D.)sound, thermal, kinetic

Answers

Answer:

I think is B. sound, nuclear, electrical

but if I wrong then I am so sorry

why the formation of sand is a physical change.

Answers

This is a physical change because there isn’t a change in composition of the substance, sand. It is only changing the shape, not having a chemical reaction of any sort.
I hope this helps!

1 lb equals how many grams

Answers

Answer:

1 lb. is 453.592 grams

Explanation:

1lb is 453.592 grams

453.592 grams hope this helps!

Given two metal balls (that are identical) with charges LaTeX: q_1q 1and LaTeX: q_2q 2. We find a repulsive force one exerts on the other to be LaTeX: 1.35\times10^{-4}N1.35 × 10 − 4 N when they are 20 cm apart. Accidentally, one the the experimenters causes the balls to collide and then repositions them 20 cm apart . Now the repulsive force is found to be LaTeX: 1.406\times10^{-4}N1.406 × 10 − 4 N. What are the initial charges on the two metal balls?

Answers

Answer:

[tex]q_1=\pm0.03 \mu C[/tex] and [tex]q_2=\pm0.02 \mu C.[/tex]

Explanation:

According to Coulomb's law, the magnitude of  force between two point object having change [tex]q_1[/tex] and [tex]q_2[/tex] and by a dicstanced is

[tex]F_c=\frac{1}{4\pi\spsilon_0}\frac{q_1q_2}{d^2}-\;\cdots(i)[/tex]

Where, [tex]\epsilon_0[/tex] is the permitivity of free space and

[tex]\frac{1}{4\pi\spsilon_0}=9\times10^9[/tex] in SI unit.

Before  dcollision:

Charges on both the sphere are [tex]q_1[/tex] and [tex]q_2[/tex], d=20cm=0.2m, and [tex]F_c=1.35\times10^{-4}[/tex] N

So, from equation (i)

[tex]1.35\times10^{-4}=9\times10^9\frac{q_1q_2}{(0.2)^2}[/tex]

[tex]\Rightarrow q_1q_2=6\times10^{-16}\;\cdots(ii)[/tex]

After dcollision: Each ephere have same charge, as at the time of collision there was contach and due to this charge get redistributed which made the charge density equal for both the sphere t. So, both have equal amount of charhe as both are identical.

Charges on both the sphere are mean of total charge, i.e

[tex]\frac{q_1+q_2}{2}[/tex]

d=20cm=0.2m, and [tex]F_c=1.406\times10^{-4}[/tex] N

So, from equation (i)

[tex]1.406\times10^{-4}=9\times10^9\frac{\left(\frac{q_1+q_2}{2}\right)^2}{(0.2)^2}[/tex]

[tex]\Rightarrow (q_1+q_2)^2=2.50\times10^{-15}[/tex]

[tex]\Rightarrow q_1+q_2=\pm5\times 10^{-8}[/tex]

As given that the force is repulsive, so both the sphere have the same nature of charge, either positive or negative, so, here take the magnitude of the charge.

[tex]\Rightarrow q_1+q_2=5\times 10^{-8}\;\cdots(iii)[/tex]

[tex]\Rightarrow q_1=5\times 10^{-8}-q_2[/tex]

The equation (ii) become:

[tex](5\times 10^{-8}-q_2)q_2=6\times10^{-16}[/tex]

[tex]\Rightarrow -(q_2)^2+5\times 10^{-8}q_2-6\times10^{-16}=0[/tex]

[tex]\Rightarrow q_2=3\times10^{-8}, 2\times10^{-8}[/tex]

From equation (iii)

[tex]q_1=2\times10^{-8}, 3\times10^{-8}[/tex]

So, the magnitude of initial charges on both the sphere are [tex]3\times10^{-8}[/tex] Coulombs[tex]=0.03 \mu C[/tex] and [tex]2\times10^{-8}[/tex] Colombs or [tex]0.02 \mu C[/tex].

Considerion the nature of charges too,

[tex]q_1=\pm0.03 \mu C[/tex] and [tex]q_2=\pm0.02 \mu C.[/tex]

I shoot a water balloon catapult at the end of the year rally with a velocity of
57m/s at 31 degrees. What velocity does it hit the ground with?

Answers

Answer:

29.36 [tex]m/s[/tex] downwards

Explanation:

Use the equation [tex]v^{2} =u^{2} +2as[/tex]

Choose upwards as positive

v=?

u= 57sin31 (vertical component of initial velocity)

a= -9.8

s=0

[tex]v^{2} = (57sin31)^2 +2(-9.8)(0)[/tex]

v=29.36 [tex]m/s[/tex] downwards

During a phase change, a substance undergoes a(n) *

HELP

reversible change from one state to another.

irreversible change to a different substance

irreversible change from one state to another.

reversible change to a different substance.

Answers

Answer:

Reversible change from one state to another

Hope this helps

:)

what are contact force and non contact force give example​

Answers

Explanation:

Force is push or pull on a body.

Contact force is a force that requires contact. It acts between two body that touches on another.

Examples are pushing a car, ringing a bell, kicking a ball.

Non contact forces are forces applied to another object without contact. The action of this force is usually through a targeted force field.

Examples are magnetic force, gravitational force

PLEASE HELP :) <3
Describe some ways people can reduce the risks of being harmed by volcanoes and/or earthquakes.

Answers

Protection in a volcanic ashfall:

Stay inside, if possible, with windows and doors closed.

Wear long-sleeved shirts and long pants.

Use goggles to protect your eyes.

Keep your car or truck engine switched off.

Protection from earthquake if you're indoors:

Drop down and take cover under a desk or table

Stay inside until the shaking stops and it is safe to exit.

Stay away from bookcases and other furniture that can fall on you.

Stay away from windows and light fixtures.

If you are in bed – hold on and stay there.

Answer:

best way is to remain inside ur home or under any table

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