Which two substances are elements?

A. sand and air B. salt and sand
C. iron and helium
D. helium and water

Answers

Answer 1
C, iron and helium are elements since they consist of only one type of atoms

Related Questions

Someone help me with this PE question?

Answers

Answer:

Your abdominals

Explanation:

I think it is your core

A stunt man jumps from a burning building and comes to
rest at ground level. Consider his impulse during landing if
he lands on a soft mat, on a concrete surface, or in a safety
net. Which of the following is true?
a. His impulse is greatest if he lands on a soft mat.
b. His impulse is greatest if he lands on a concrete
surface.
c. His impulse is greatest if he lands in a safety net.
d. The impulse is the same in all three cases.
e. There is zero impulse in all three cases because he
comes to rest.

Answers

Answer:

I think it's E it just sounds right to me tbh

Explanation:

The driver of a car traveling at 21.6 m/s applies the brakes and undergoes a constant deceleration of 1.86 m/s 2 . How many revolutions does each tire make before the car comes to a stop, assuming that the car does not skid and that the tires have radii of 0.35 m

Answers

Answer:

each tire made 57.03 revolutions before the car halted

Explanation:

Given that;

Initial Velocity u =  21.6 m/s

final velocity v = 0 m/s

acceleration = -  1.86 m/s²

radii r = 0.35 m

first we calculate distance travelled by the car to stop;

v² - u² = 2as

s = v² - u² / 2a

we substitute

s = (0² - (21.6)² / 2 × (-1.86)

s = (0 - 466.56) / ( - 3.72 )

s = 125.419 m

Now Distance traveled by each tire in 1 revolution = 2πr

i.e 2πr is travelled in 1 revolution

so

n×2πr = 125.419 m

n = 125.419 m / 2πr

n = 125.419 m / 2π(0.35)

n = 125.419 / 0.7π

n = 57.03 revolutions

Therefore, each tire made 57.03 revolutions before the car halted

A student drives the 105-mi trip back to campus after spring break and travels with an average speed of 53 mi/h for 1 hour and 30 minutes for the first part of the trip. (a) What distance was traveled during this time?

Answers

Answer:

79.5 miles.

Explanation:

From the question given above, the following data were obtained:

Average speed = 53 mi/h

Time = 1 hr 30 minutes

Distance travelled =?

Next, we shall convert 1 hr 30 minutes to hours. This can be obtained as follow:

Recall:

1 hr = 60 mins

Therefore,

1 hr 30 mins = 60 + 30 = 90 minutes.

60 mins = 1 hr

Therefore,

90 mins = 90 mins × 1 hr / 60 mins

90 mins = 1.5 hr

Finally, we shall determine the distance travelled during the time. This can be obtained as follow:

Average speed = 53 mi/h

Time = 1.5 hr

Distance travelled =?

Average speed = Distance travelled / time

53 = Distance travelled / 1.5

Cross multiply

Distance travelled = 53 × 1.5

Distance travelled = 79.5 miles

Calculate the change in momentum of a ball has 35 kg mass and it changed its velocity from 3m/s to 6 m/s
please hellllpppppp

Answers

Answer:

105 kg.m/s

Explanation:

Formula for change in momentum is given as;

ΔP = m(v - u)

We are given;

Mass; m = 35 kg

Initial velocity; u = 3 m/s

Final velocity; v = 6 m/s

Thus;

ΔP = 35(6 - 3)

ΔP = 35 × 3

ΔP = 105 kg.m/s

A car traveling 85 km/h is 250 m behind a truck
traveling 73 km/h.

Answers

Time needed = t = 20.83 s

Further explanation

Given

car speed = 85 km/h

truck speed = 73 km/h

Required

the time it takes for the car to reach the truck

Solution

When the car reaches the truck, the distance between them will be the same

x car - 250 m = x truck

General formula for distance (d) :

d = v.t

So the equation becomes :

85t-250 = 73t

12t=250

t = 20.83 s

An object is traveling at a velocity of 100 rn/s to the left for about 5 seconds. How far has the object traveled? (What is the distance?)

Answers

Answer:

500 rn

Explanation:

In a game of ice hockey, you use a hockey stick to hit a puck of mass 0.16 kg that slides on essentially frictionless ice. During the hit you exert a constant horizontal force on the puck that gives it an acceleration of 75 m/s2 for a fraction of a second. During the hit, what is the magnitude of the horizontal force that you exert on the puck

Answers

Answer:

12N

Explanation:

given- mass, acelation

Fnet=ma= .16kg*75m/s2

Fnet=12 N only force no friction given.

Anastasia constructed a simple circuit with a battery and a light bulb. She knows that the resistance of the light bulb is 10
2 and that the voltage given to the light bulb is 12 V. What is the current through the light bulb?

Answers

Answer:

Simple Single Loop Circuits. J. E σ. = ∆V = IR ... To find the current, use the total voltage and equivalent resistance: S. V ... A circuit contains a 48-V battery and two 240Ω light bulbs.

A woman is reported to have fallen 144 ft from the 17th floor of a building, landing on a metal ventilator box that she crushed to a depth of 18.0 in. She suffered only minor injuries. Ignoring air resistance, calculate
A) The speed of the woman just before she collided with the ventilator.
B) Her average acceleration while in contact with the box.
C) Modeling her acceleration as constant, calculate the time interval it took to crush the box.

Answers

Answer:

Okay uh gimme some time though

For each scenario below, choose the best graph.
(a) Maria bikes from home to work.

Answers

A line graph that plots either speed or distance against time.

Really, the type of graph depends on what quantity you want the graph to show.

The surface area of a postage

stamp is 0.00600 m^2, and the air

exerts 1.00 atm of pressure on it.

How much force does it exert on

the stamp?

(Hint: The standard unit for

pressure is Pa.)

(Unit = N)

Answers

Answer:

Force = 607.95 Newton

Explanation:

Given the following data;

Area = 0.00600 m^2

Pressure = 1 atm to Pascal = 101325 Pa

To find the force;

Pressure = Force/area

Force = pressure * area

Substituting into the equation, we have;

Force = 101325 * 0.00600

Force = 607.95 Newton.

Therefore, the amount of force exerted by the air on the stamp is 607.95 Newton.

9. What is the speed of a 25 kg object that has 2500 J of kinetic energy?

Answers

Answer:

We conclude that the speed of a 25 kg object that has 2500 J of kinetic energy is 14.14 m/s.

Explanation:

Given

Mass m = 25 kg Kinetic Energy (K.E) = 2500 J

To determine

The speed v = ?

We know that a body can possess energy due to its movement — Kinetic Energy.

The speed with which a body moves can be determined using the formula

[tex]K.E=\frac{1}{2}mv^2[/tex]

[tex]v=\sqrt{\frac{2\times \:K.E}{m}}\:\:\:[/tex]

substituting m = 25 and K.E = 2500 in the formula

[tex]v=\sqrt{\frac{2\times 2500}{25}}[/tex]

[tex]v=\sqrt{\frac{5000}{25}}[/tex]

[tex]v=\sqrt{200}[/tex]

[tex]v=14.14[/tex] m/s

Therefore, we conclude that the speed of a 25 kg object that has 2500 J of kinetic energy is 14.14 m/s.

A taxi hurries with a constant speed of 60 miles per hour. How long will it take to travel a distance of 130 miles

Answers

Answer:

2.17 hrs

Explanation:

time = distance / velocity

We know that distance = 130 miles and velocity = 60 miles/h.

t = d / v

t = 130 miles / 60 miles/h

t = 2.17 hrs

It takes about 2.17 hours to travel a distance of 130 miles. Hope this helps, thank you !!

Sort the following properties as quantitative or qualitative property MASS-DENSITY-VOLUME-MELTING POINT

Answers

Answer:

mass, volume: quantitative propereties: extensive properties

volume, melting point: quantitative propereties: intensive properties

Explanation:

The quantitative properties of matter are characteristics of matter that can be measured and of which quantities can be expressed.

Quantitative properties can be divided into 2 groups:

Extensive properties: This is whose value depends on the amount of substance analyzed. They are not properties that allow us to distinguish one substance from another, since its value changes depending on the size of the object or sample that you have. Intensive properties: are those that do not depend on the mass or size of a body. That is, these are properties whose value is independent of the amount of substance analyzed; they are useful for differentiating substances.

On the other hand, the qualitative properties of matter are those that cannot be expressed in numerical values ​​or quantities. They are detected, in many cases, through the senses, since they do not measure them.

In this case:

mass, volume: quantitative propereties: extensive propertiesvolume, melting point: quantitative propereties: intensive properties

6. A baseball player hits a 0.155-kilogram fastball traveling at -44.0 m/s into center field at a speed of 50.0

m/s. If the impact lasts for 0.00450 second, with what force does he hit the

baseball?

Answers

Answer:

3,237.78N

Explanation:

According to Newton's second law of motion

F = mass * acceleration

Since a = v-u/t

F = m(v-u)/t

Given

Mass m = 0.155kg

v = 50.0m/s

u = -44.0m/s

Time t = 0.00450secs

Substitute

F = 0.155(50-(-44))/0.00450

F = 0.155(50+44)/0.00450

F = 0.155(94)/0.00450

F = 14.57/0.00450

F = 3,237.78N

hence he hit the baseball with a force of 3,237.78N

How does energy keep the world going? How is energy conserved?​

Answers

Answer:

The most notable way that reducing energy helps the environment is by decreasing power plant emissions.

Answer:

Explanation:

The conservation of energy law states that energy cant be created or destroyed, only transferred. Since energy cant be created or destroyed, the amount of energy in the universe is completely constant.

Energy keeps the world "going" because we use it every single day in our life. Everything in the universe uses some sort of energy. We digest food for energy, we use electrical energy for electronics, we convert electrical energy into heat energy for heaters and such, we use solar panels to power our houses. There are countless examples of how energy keeps the world "going."

pls help ;-; this is the question btw

Answers

The answer is "Infrared"

Hope this helps

Answer:

x-rays

Explanation:

A pendulum is placed on a distant planet. The length is one meter, and the measured period is 1.4 seconds, what is the acceleration of gravity on that planet?

Answers

Answer:

[tex]a=20.14\ m/s^2[/tex]

Explanation:

The time period of the simple pendulum is given by :

[tex]T=2\pi \sqrt{\dfrac{l}{g}}[/tex]

l is the length of the pendulum

g is the acceleration due to gravity

We have,

T = 1.4 s, l = 1 m

So,

[tex]T^2=\dfrac{4\pi^2 l}{g}\\\\g= \dfrac{4\pi^2 l}{T^2}\\\\g= \dfrac{4\pi^2 \times 1}{(1.4)^2}\\\\g=20.14\ m/s^2[/tex]

So, the acceleration due to gravity of that planet is [tex]20.14\ m/s^2[/tex].

A cart was allowed to roll down a ramp from rest. It reached the bottom of the ramp with a speed of 25 cm/s. A student could conclude that the cart

Answers

Answer:

A student could conclude that the cart gained momentum as it rolled down.

Explanation:

If the cart was allowed to roll down the ramp from rest, it means that the initial velocity of the cart is zero (0). Also, if the final velocity of the cart became 25 cm/s, it means that the velocity of the cart increased from 0 to 25 cm/s.

Therefore, A student could conclude that the cart gained momentum as it rolled down.

Cheetahs can accelerate to a speed of 20.0 m/s in 2.50 s and can continue to accelerate to reach a top speed of 30.0 m/s. Assume the acceleration is constant until the top speed is reached and is zero thereafter. Let the +x-direction point in the direction the cheetah runs. Express the cheetah’s top speed (vtop) in miles per hour (mi/h).
Starting from a crouched position, how much time (t-accel) does it take a cheetah to reach its top speed, and what distance (d) does it travel in that time?

Answers

Answer:

The cheetah’s initial velocity is 0 m/s. Let’s use the following equation to determine the acceleration.

Explanation:

Acceleration = (v/t) = (20/2.5) = 8m/sec^2.

1) Time to 29m/sec. = (v/a) = (29/8) = 3.625 secs. (3.6)

Distance covered to top speed = (v^2/2a) = 52.5625 metres (52.6).

2) Distance to run at top speed = (120 - 52.5625) = 67.4375 metres.

Time = (d/v) = (67.4375/29) = 2.325 secs.

Total time to warthog = (2.325 + 3.625) = 5.95 secs.

Cheetah's top speed will be "67.12 mi/h". A complete solution is provided below.

Given that:

Speed,

20.0 m/s

Time,

2.50 s

Acceleration to top speed,

30.0 m/s

Now,

Acceleration (a) of cheetah will be:

= [tex]\frac{20}{2.5}[/tex]

= [tex]8 \ m/s^2[/tex]

Top speed ([tex]V_{top}[/tex]) of cheetah

= [tex]\frac{30}{1609}\times 3600[/tex]

= [tex]67.12 \ mi/h[/tex]

→ The time required (t) to reach the top speed will be:

= [tex]\frac{30}{8}[/tex]

= [tex]3.75 \ sec[/tex]

and,

→ The distance travelled (d) by cheetah will be:

= [tex]\frac{1}{2}\times 8\times (3.75)^2[/tex]

= [tex]\frac{1}{2}\times 8\times 14.0625[/tex]

= [tex]56.25[/tex]

Learn more:

https://brainly.com/question/13265986

Is it possible for the earth to be sucked into a black hole? If so, what would happen?

Answers

Answer:

si es posible

Explanation:

ya no existiria la tierra

if possible

the earth would no longer exist.

Answer:

Yes,

Explanation:

We would all die immediatly, its like being stretched and crushed

what are the four intermittent reinforcement schedules in your own words?

Answers

The four resulting intermittent reinforcement schedules are: Fixed interval schedule (FI) Fixed ratio schedule (FR) Variable interval schedule (VI)

What recreational drug does an alcopop contain?

Answers

Alcohol is 100% correct

An "alcopop" is a term used to describe a flavored alcoholic beverage that typically resembles a soft drink or a fruit juice in appearance and taste. It is also referred to as a "ready-to-drink" (RTD) beverage.

Alcopops are often targeted toward younger consumers and are known for their sweet and fruity flavors, which can mask the taste of alcohol.

The specific recreational drug that an alcopop contains is alcohol itself. Alcohol, or ethanol, is a psychoactive substance that can have intoxicating effects when consumed.

It is considered a recreational drug because of its ability to alter consciousness, impair judgment and coordination, and produce pleasurable or mood-altering effects.

The alcohol content in alcopops can vary, but it is typically lower than in pure spirits or liquors. This is often achieved through dilution with other ingredients, such as carbonated water or fruit juices, to create a milder alcoholic beverage.

Alcopops may also contain additional flavorings, sweeteners, and additives to enhance their taste and appeal.

Know more about alcopop:

https://brainly.com/question/33750456

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At what speed, in m/s, would a moving clock lose 1.3ns in 1.0 day according to experimenters on the ground?

Answers

Answer:

v=0.14c

Explanation:

Which statement about personal strength is TRUE?
1. It is inborn and cannot be developed with training or practice.
2. It is something you can acquire with hard work and lots of practice.
3. It is strictly a physical quality, like beauty, or physical ability, like the ability to swim fast.
4. It is such a natural part of a person that they may not even recognize it.

Answers

I think the answer would be 2 because strength can be learned and acquired with weights or other equipment

Hope this helps

Have a great day/night

Feel free to ask any questions

A crane is used to lower weights into a lake for an underwater construction project. Determine the tension in the cable of the crane due to a concrete sphere with a radius of 2 m when the sphere is lowered into the water. The concrete has a specific gravity of 2.8.

Answers

Answer:

Tension in the cable = 591292.8 N or 591.3 kN

Explanation:

Tension in the cable = Weight of object in air - upthrust/bouyancy due to the liquid

Weight of object in air = mass * acceleration due to gravity, g

Since mass is not given, it is obtained from the formula, mass = density * volume

Volume of the sphere = 4/3πr³ where r, radius = 2 m; π = 22/7

volume = 4/3 * 22/7 * (2m)³

volume of sphere = 33.52 m³

Density of concrete sphere = specific gravity * density of water

where, specific gravity = 2.8, density of water = 1000 kg/m³

density of concrete =  2.8 * 1000 kg/m³

density of concrete = 2800 kg/m³

acceleration due to gravity, g = 9.8 m/s²

Thus, weight of concrete = 2800 kg/m³ * 33.52 m³ * 9.8 m/s² = 919788.8 N

Upthrust = density of water * volume of sphere * g

Upthrust = 1000 kg/m³ * 33.52 m³ * 9.8 m/s² = 328496 N

The tension in the cable is the calculated as below;

Tension in the cable = Weight of object in air - upthrust/bouyancy due to the liquid

Tension in cable = 919788.8 N - 328.496 N = 591292.8 N

Therefore, tension in the cable is 591292.8 N or 591.3 kN

A runner completes the 200-meter dash with a time of 19.80 seconds. What was the runner's average speed in miles per hour?

Answers

Answer:

v = 22.54 mph.

Explanation:

Given that,

Distance moved, d = 200 m

Time, t = 19.8 s

We need to find the runner's average speed.

We know that,

1 mile = 1609.34 m

200 m = 0.124 miles

19.8 seconds = 0.0055 h

So,

Speed = distance/time

[tex]v=\dfrac{0.124}{0.0055}\\\\v=22.54\ mph[/tex]

So, the runner's average speed is 22.54 mph.

A ball player catches a ball 3.10 s after throwing it vertically upward. a) with what speed did he throw it? b) what height did it reach?​

Answers

Answer:

speed=30.41, height=94.27

Explanation:

since the motion is vertical upward means the motion is against gravitational force and the initial velocity of the ball was zero.

if |v|= 11, |w|= 23, |v-w|= 30, find |v+w|​

Answers

Answer:

[tex]|v+w|=20[/tex]

Explanation:

We are given that

|v|=11

|w|=23

|v-w|=30

We have to find the value of |v+w|

|a-b|^2=(a+b)\cdot (a+b)=a^2+b^2-2|a||b|cos\theta

Using the formula

[tex](30)^2=(11)^2+(23)^2-2(11)(23)cos\theta[/tex]

[tex]900=121+529-506cos\theta[/tex]

[tex]900-121-529=-506cos\theta[/tex]

[tex]250=-506cos\theta[/tex]

[tex]cos\theta=-\frac{250}{506}[/tex]

[tex]|a+b|^2=|a|^2+|b|^2+2a\cdot bcos\theta[/tex]

Using the formula

[tex]|v+w|^2=(11)^2+(23)^2+2(11)(23)\times (-\frac{250}{506})[/tex]

[tex]|v+w|^2=400[/tex]

[tex]|v+w|^2=(20)^2[/tex]

[tex]|v+w|=20[/tex]

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