1.) What is the half-life of a 100.0 g sample of nitrogen-16 that decays to 12.5 grams in 21.6 seconds?​

Answer:

Qúéßtîóñ : A quantity of pepper soup of mass 800g poured into a plastic container with a tight fitting lid has a temperature of 30oC. The container is then placed in a microwave oven, rated 1200 W and operated for3 minutes.

(i) Calculate the final temperature attained by the soup. (Assuming no heat losses)

Àñßwër : Pt = mc

1200 x 3 x 60 = x 4000 x

= 67.5o

Final temp = 67 . 5o + 30o

= 97.5oC

(ii) Explain why containers with tight-fitting lids are not suitable for use in microwave cooking.

Àñßwër : The molecules of the steam from the content are confined within the container. As the temperature increases the rate of collision of the molecules with walls of the container increases, thus the pressure inside the container increases. If it is tightly fitted, the pressure can make the container burst thus releasing its hot content.

(iii) When the soup is brought out and allowed to cool, a dent was observed on the container. Explain.[ Take specific heat capacity of the soup = 4000 Jkg-1 K-1 ]

Àñßwër: The container will dent because the condensation of the steam in the container will lead to a decrease in pressure in the container making the atmospheric pressure greater than the pressure in the container.

Explanation:

Answer:

Yes. Anytime the velocity is constant, the acceleration is zero. For example, a car traveling at a constant 90 km/h in a straight line has nonzero velocity and zero acceleration.

:)

brainlest plz, i really need it

Answer:

They will attract when its north and south but will repel when its south and south or north and north

Answer:

m = 6.73 kg

Explanation:

Given that,

The normal force acting on the crate = 66 N

We need to find the mass of the crate.

Normal force = weight of the crate

N = mg

m is mass of the crate

[tex]m=\dfrac{N}{g}\\\\m=\dfrac{66}{9.8}\\\\m=6.73\ kg[/tex]

So, the mass of the carte is 6.73 kg.

Explanation:

W=Fdcos0

=45×7.3cos30

=284.4J

Answer:

0.641 seconds

Explanation:

Distance (d) = 1.0 km

Using the relation :

Speed = distance / time

Time = distance / speed

Speed of sound in seawater is about 1560 m/s

Distance = 1.0km =

1km = 1000m

Time = 1000 / 1560

Time = 0.6410256

Time = 0.641 s

Answer:

Release

Explanation:

The water is heated until

Answer: 721.13

Explanation:

The density of the gasoline will be "721.13 kg/m²". To understand the calculation, check below.

According to the question,

Mass, m = 58.7 kg

Volume, V = 0.0814 m³

We know the relation,

→ Density = [tex]\frac{Mass}{Volume}[/tex]

or,

→            d = [tex]\frac{m}{V}[/tex]

By substituting the values, we get

                = [tex]\frac{58.7}{0.0814}[/tex]

                = 721.13 kg/m²

Thus the above approach is correct.

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Answer:

D

Explanation:

i did that yesterday and your welcome homie b

Answer:

The atomic number of Aluminum is "13"!

Explanation:

The 27 means the atomic mass is 27 . The number of protons plus the number of neutrons is 27. That means the number of neutrons is 27–13=14. Number of neutrons depends on the isotopic form of aluminium.

Answer:

loloololo

lol

Explanation:

lolloolololo

Answer:

I belive that the 2000 kg will be going faster then the 1000kg

Explanation:

Because it is 2x as heavy as the other car which means it most likely would hit the car and keep going because it can hit it so hard that the car dosent hit effected

Answer:

Nuclear energy

Explanation:

The nucleus holds the energy together

Answer:

203.1J

Explanation:

Given parameters:

Mass  = 65kg

Speed  = 2.5m/s

Unknown:

Kinetic energy of jogger  = ?

Solution:

To solve this problem, we use the kinetic energy equation:

    K.E  = [tex]\frac{1}{2}[/tex] m v²  

m is the mass

v is the velocity

 Now insert  the parameters and solve;

  K.E  =  [tex]\frac{1}{2}[/tex] x 65 x 2.5²   = 203.1J

Answer:

because the distance increased while the speed stayed the same

Explanation:

Answer: A curved line on a distance time graph tell us that the speed is changing but the object is either getting faster or the accelerating or slowing down the decelerating.

Explanation: Hope this helps

Answer:

Yes

Explanation:

Certain types of weathering are more common in certain environments than others.

This is very true.

Answer:

Where is the question?

Explanation:

Answer:

A

Explanation:

ap3x

Answer:

A. Refraction

Explanation:

<3

Answer:

I think the anwser is b

Explanation:

because as altitude increase pressure therefore decreases

Answer:

C. Talk test

Explanation:

The talk test would be readily available to me at the the least cost.

The talk test is about the easiest way that one can monitor intensity as they exercise. Because the only thing needed here is the ability to talk and to breathe.

The intensity lies on if one can talk and breathe at the same time. The harder one exercises, the more breathless they become and they find it difficult to talk.

Answer:

c

Explanation:

Answer:

3.

Explanation:

If the astronaut in the video wanted to move upward, he should throw the object downward because according to Newton’s third law, the object will then exert a force on him in the opposite direction (i.e., upward). hence, option (3) is correct.

Newton's Third Law states that if object A exerts a force on object B, then object B must apply a force to object A that is equal in magnitude and directed in the opposite direction.

This law represents a specific symmetry in nature: forces always exist in pairs, and no body can exert a force without also being subjected to one.

Hence, if the astronaut in the video wanted to move upward, he should throw the object downward and  the object will then exert a force on him in the opposite direction (i.e., upward).

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Answer:

The bending occurs because light travels more slowly in a denser medium.

Answer:

The magnitude of the coefficient of kinetic friction is approximately 1.304 × 10⁻⁵

Explanation:

The given parameters are;

The time it takes for the box to stop, "t" = 600 seconds

The distance the box moves before coming to a stop, "d" = 23 meters

The work done by the friction force to stop the block = The kinetic energy lost by the box

The work done by the friction force to stop the block = [tex]\mu _k[/tex]·m·g·d

The kinetic energy change of the block = 1/2·m·u²

Where;

g = The acceleration due to gravity = 9.8 m/s²

m = The mass of the box

[tex]\mu _k[/tex] = The coefficient of kinetic friction

d = The distance travelled by the block = 600 m

u = The initial velocity of the block

∴ [tex]\mu _k[/tex]·m·g·d = 1/2·m·u²

[tex]\mu _k[/tex]·g·d = 1/2·u²

[tex]\mu _k[/tex] = 1/2·u²/(g·d) = 1/2·u²/(9.8 × 23) = u²/450.8

∴  [tex]\mu _k[/tex] = u²/450.8...(1)

The kinematic equation of motion of the block can be presented as follows;

v = u - a·t

Where;

v = The final velocity = 0 m/s (The block slides to a stop)

u = The initial velocity

a = The acceleration of the block (the minus sign indicates that the block's velocity is decreasing)

t = The time of motion of the block = 600 seconds

Therefore, by substituting the above values, we have;

0 = u - 600·a

∴ u = a·600

The kinematic equation of motion for the distance moved by the block, "s" can be expressed as follows;

s = u·t - 1/2·a·t²

Where;

s = The distance moved by the bloc = 23 meters

∴ 23 = a·600·600 - 1/2·a·600² = 360,000·a - 1/2·a·360,000 = 180,000·a

a = 23/(180,000)

u = 600 × (23/(180,000)) = 23/300

The initial velocity, u = 23/300 m/s

From equation (1), we have;

[tex]\mu _k[/tex] = u²/(450.8) = (23/300)²/450.8 = 23/1764000 ≈ 1.304 × 10⁻⁵

The magnitude of the coefficient of kinetic friction, [tex]\mu _k[/tex] ≈ 1.304 × 10⁻⁵

Answer:

42 °

Explanation:

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

Force (F) = 45 N

Workdone (Wd) = 50 J

Distance (d) = 1.5 m

Angle (θ) =.?

Angle at which the box is pulled can be obtained as:

Wd = Fd × Cos θ

50 = 45 × 1.5 × Cos θ

50 = 67.5 × Cos θ

Divide both side by 67.5

Cos θ = 50 / 67.5

Cos θ = 0.7407

Take the inverse of Cos

θ = Cos¯¹ 0.7407

θ = 42.2 ≈ 42 °

Thus, the angle at which the box is pulled is approximately 42 °.

Answer:

0.05s

Explanation:

frequency = speed / wavelength = 20/1 = 20Hz. Thus period = 1/f = 1/20 = 0.05 s

This question involves the concepts of wave speed and wavelength.

The period of the wave is "0.05 s".

The wave speed is given in terms of wave frequency and wavelength as follows:

[tex]v=f\lambda\\\\f=\frac{v}{\lambda}[/tex]

where,

Therefore,

[tex]f=\frac{20\ m/s}{1\ m}\\\\[/tex]

f = 20 Hz

Now, the period of the wave is the reciprocal of the frequency of the wave:

[tex]Period = T=\frac{1}{f}\\\\T=\frac{1}{20\ Hz}[/tex]

T = 0.05 s

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Answer:

a = 2 m/s^2

Explanation:

the solution is already done for you. Its just whats 20 divided by 10 which is 2.

Answer:

Explanation:

All objects radiate energy.