Which of the following are valid expressions?

Note that the correct times are t = 0, t = 1/4, t = 1/2. You can tell from the spaces between the two digits. i.e 1&4 and 1&2

Answer:

y(0) = 2.00 cm

y(1/4) = 1.56 cm

y(1/2) = 1.21 cm

Explanation:

This is a very simple exercise, the displacement of the oscillating weight from equilibrium has already been modeled by the equation:

[tex]y(t) = 2e^{-t} cos 4t[/tex]

Where y = displacement ( in cm)

and t = time (in seconds)

The task is to find the displacement when t = 0, 1/4 and 1/2

When t = 0 s

[tex]y(0) = 2e^{0} cos 4(0)\\y(0) = 2* 1*1\\y(0) = 2.00 cm[/tex]

When t = 1/4 s

[tex]y(1/4) = 2e^{-1/4} cos 4(1/4)\\y(14) = 2e^{-1/4} cos (1)\\y(1/4) = 1.56 cm[/tex]

When t = 1/2

[tex]y(1/2) = 2e^{-1/2} cos 4(1/2)\\y(14) = 2e^{-1/2} cos (2)\\y(1/2) = 1.21 cm[/tex]

Answer:

There must be an equal amount of each element on both sides of the equation. Hope this helps and please marks as the brainliest.

Explanation:

Answer:

The answer is D

Explanation:

Hope this helps!

Answer:

C: Valence electrons are transferred from a metal to a nonmetal

Explanation:

In ionic bonds, the metal loses electrons to become a positively charged cation, whereas the nonmetal accepts those electrons to become a negatively charged anion.

hope this was helpful :)

Answer:

The maximum height that a cannonball fired at 420 m/s at a 53.0° angles is 5740.48m.

hmax = 5740.48 m

Explanation:

This is an example of parabolic launch. A cannonball is fired on flat ground at 420 m/s at a 53.0° angle and we have to calculate the maximum height that it reach.

V₀ = 420m/s and θ₀ = 53.0°

So, when the cannonball is fired it has horizontal and vertical components:

V₀ₓ = V₀ cos θ₀ = (420m/s)(cos 53°) = 252.76 m/s

V₀y = V₀ cos θ₀ = (420m/s)(cos 53°) = 335.43m/s

When the cannoball reach the maximum height the vertical velocity component is zero, that happens in a tₐ time:

Vy = V₀y - g tₐ = 0

tₐ = V₀y/g

tₐ = (335.43m/s)/(9.8m/s²) = 34.23s

Then, the maximum height is reached in the instant tₐ = 34.23s:

h = V₀y tₐ - 1/2g tₐ²

hmax = (335.43m/s)(34.23s)-1/2(9.8m/s²)(34.23s)²

hmax = 11481.77m - 5741.29m

hmax = 5740.48m

Answer: The material that is not a mixture; it has the same properties all the way through is called a substance.

Explanation:

A pure substance is a form of matter that has a constant composition and properties that are constant throughout the sample. Hence, it cannot be separated by physical means. Example: Gold

Mixture is a substance which has two or more components which do not combine chemically and do not have any fixed ratio in which they are present. They can be separated by physical means as well. Example: Air

Thus the material that is not a mixture; it has the same properties all the way through is called a substance.

Answer:

The reason is because the pressure of the air inside the room drops with time which makes opening the door to require an increased amount of force to make up for the reduced pressure inside the room

Explanation:

From the kinetic theory of gases we have the following relation;

[tex]v_{rms} = \sqrt{\dfrac{3 \cdot K \cdot T}{m} }[/tex]

[tex]p = \dfrac{n \cdot MW \cdot v^2_{rms} }{3 \cdot V}[/tex]

Where:

K = Boltzmann constant

T = Temperature

m = Mass

MW = Molecular weight

V = Volume

[tex]v_{rms}[/tex] = Root mean square velocity

Whereby the room door is closed, the kinetic energy of the air particles will be used up such that the average velocity of the particles will decrease, given that the volume of the room is constant, the pressure inside the room will drop below the original pressure outside the room such that the force on the door due to the outside pressure is larger than the force on the door from inside the room requiring a larger amount of force to overcome the resistance of the now higher outside pressure force.

Answer:

i can not read that sorry

Answer:

a. frequency = 25 Hz, period = 0.04 s , wave number = 19.63 rad/m

b. y = (0.0700 m)sin[(19.63 rad/m)x - (157.08 rad/s)t]

c.  0.0496 m

d. 0.03 s

Explanation:

a. Frequency, f = v/λ where v = wave speed = 8.00 m/s and λ = wavelength = 0.320 m

f = v/λ = 8.00 m/s ÷ 0.320 m = 25 Hz

Period, T = 1/f = 1/25 = 0.04 s

Wave number k = 2π/λ = 2π/0.320 m = 19.63 rad-m⁻¹

b. Using y = Asin(kx - ωt) the equation of a wave

where y = displacement of the wave, A = amplitude of wave = 0.0700 m and ω = angular speed of wave = 2π/T = 2π/0.04 s = 157.08 rad/s

Substituting the variables into y, we have

y = (0.0700 m)sin[(19.63 rad/m)x - (157.08 rad/s)t]

c. When x = 0.360 m and t = 0.150 s, we substitute these into y to obtain

y = (0.0700 m)sin[(19.63 rad/m)x - (157.08 rad/s)t]

y = (0.0700 m)sin[(19.63 rad/m × 0.360 m) - (157.08 rad/s × 0.150 s)]

y = (0.0700 m)sin[(7.0668 rad) - (23.562 rad)]

y = (0.0700 m)sin[-16.4952 rad]

y = (0.0700 m) × 0.7084

y = 0.0496 m

d. For the particle at x = 0.360 m to reach its next maximum displacement, y = 0.0700 m at time t. So,

y = (0.0700 m)sin[(19.63 rad/m)x - (157.08 rad/s)t]

0.0700 m = (0.0700 m)sin[(19.63 rad/m × 0.360 m) - (157.08 rad/s)t]

0.0700 m = (0.0700 m)sin[(7.0668 rad - (157.08 rad/s)t]  

Dividing through by 0.0700 m, we have

1 = sin[(7.0668 rad - (157.08 rad/s)t]

sin⁻¹(1) = 7.0668 rad - (157.08 rad/s)t  

π/2 = 7.0668 rad - (157.08 rad/s)t

π/2 - 7.0668 rad = - (157.08 rad/s)t

-5.496 rad = - (157.08 rad/s)t

t = -5.496 rad/(-157.08 rad/s) = 0.03 s

The frequency of the wave is 25 Hz, the period is 0.04 s, and the wave number of the given wave is 19.63 rad/m.

(A) Frequency of the wave,

[tex]\bold {f = \dfrac v{\lambda}}[/tex]

where

v - speed = 8.00 m/s

λ - wavelength = 0.320 m

[tex]\bold {f = \dfrac {8.0 m/s }{0.32\ m} = 25\ Hz}[/tex]

Period of the wave,

[tex]\bold {T = \dfrac 1f = \dfrac 1{25 } = 0.04\ s }[/tex]

Wave number of the wave,

[tex]\bold {k = \dfrac {2\pi }{\lambda} = \dfrac {2\pi }{0.320} = 19.63\ rad\ m^{-1}}[/tex]

(B)

Wave function equation of a wave,

y = A sin (kx - ωt)

where

y - displacement of the wave

A = amplitude  = 0.0700 m

ω = angular speed  = 2π/T = 2π/0.04 s = 157.08 rad/s

Put the values in the formula,

y = (0.0700 m)sin[(19.63 rad/m)x - (157.08 rad/s)t]

(C) When x = 0.360 m and t = 0.150 s,

y = (0.0700 m)sin[(19.63 rad/m × 0.360 m) - (157.08 rad/s × 0.150 s)]

y = 0.0496 m

Therefore, the frequency of the wave is 25 Hz, the period is 0.04 s, and the wave number of the given wave is 19.63 rad/m.

To know more about waves,

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Answer:

a. All the laboratory equipment given are very basic equipment used in all the laboratories. Name of each equipment is as follows:

b. Use of each laboratory equipment identified is:

Answer:

When a body is moving on a circle it is accelerating because centripetal acceleration is always acting on it towards the center.

Please see the attached picture...

From the above diagram,we can say the acceleration is always acting on the body when it moves in a circle.

Hope this helps.......

Good luck on your assignment.......

Answer:

an object moving in uniform circular motion is moving in a circle with a uniform or constant speed. The velocity vector is constant in magnitude but changing in direction. Because the speed is constant for such a motion, many students have the misconception that there is no acceleration. "After all," they might say, "if I were driving a car in a circle at a constant speed of 20 mi/hr, then the speed is neither decreasing nor increasing; therefore there must not be an acceleration." At the center of this common student misconception is the wrong belief that acceleration has to do with speed and not with velocity. But the fact is that an accelerating object is an object that is changing its velocity. And since velocity is a vector that has both magnitude and direction, a change in either the magnitude or the direction constitutes a change in the velocity. For this reason, it can be safely concluded that an object moving in a circle at constant speed is indeed accelerating. It is accelerating because the direction of the velocity vector is changing.

Explanation: hopes it help u

Answer: find the answer in the explanation

Explanation:

1.) More thermal energy will be required to raise the temperature of 2 Kg of a substance by 10°C than is required to raise the temperature of 1 Kg of the same substance by 10°C. 

Because the thermal energy depends on the mass of an object.

If the two materials are the same, then they will have the same specific heat capacity. Thermal energy can be expressed as:

H = MCØ

Where

M = mass of the body

C = specific heat capacity

Ø = change in temperature

H = thermal energy

If u substitute the two values of masses into the formula above, then, the mass of 2kg will produce higher thermal energy .

Il.) Heat causes expansion. Using kinetic theory to explain this, the molecules of solid material are in a fixed pattern, held together with strong bonds. When heat is applied to the solid, the molecules will start vibrating in their fixed position. As a result of this, the bond between the molecules begins to loss. This eventually lead to expansion of solid.

Answer: calculate the free fall distance and velocity without air resistance from, the free fall.

Explanation:

To find out something's speed (or velocity) after a certain amount of time, you just multiply the acceleration of gravity by the amount of time since it was let go of. So you get: velocity = -9.81 m/s^2 * time, or V = gt. The negative sign just means that the object is moving downwards

Answer: B

V = 7576 m/s

Explanation: Given that the

circular radius R = 7,000,000 m,

The acceleration due to Earth's gravity is 8.2 m/s2

Let's use gravitational field strength formula to get the mass of the satellite.

g = Gm/R^2

Where G = 6.674×10^−11m3⋅kg−1⋅s−2

Substitutes all the parameters into the formula

8.2 = (6.674×10^-11 × M)/(7000000)^2

Cross multiply

4.018 × 10^14 = 6.674×10^−11M

Make M the subject of formula

M = 4.018 × 10^14 ÷ 6.674×10^−11

M = 6.02 × 10^24 kg

The Force of attraction experienced by the satellite will be

F = mg

F = 6.02 × 10^24 × 8.2

F = 4.94 × 10^25 N

But centripetal force is

F = MV^2/ R

Where V = velocity of the satellite

Substitute F, M and R into the formula

4.94×10^25 = (6.02×10^24V^2)/ 7 ×10^6

Cross multiply

3.46 × 10^32 = 6.02×10^24V^2

Make V^2 the subject of formula

V^2 = 3.46×10^32 ÷ 6.02×10^24

V^2 = 57403600.2

Find the square root of the value to get V

V = 7576 m/s

The required velocity of the satellite is 7576 m/s approximately

Answer:

  (vix, viy) = (14.7 m/s, 10.3 m/s)

Explanation:

The velocities of interest are ...

  (vix, viy) = (vi)(cos(35°), sin(35°)) = (18 m/s)(cos(35°), sin(35°))

  (vix, viy) = (14.7 m/s, 10.3 m/s)

Answer:

First one = 14.7

Second one = 10.3

Explanation:

EDGE

Answer:

They are the physical parts of a computer.

examples :monitor,keyboard,system unit and mouse.

Answer:

Resultant force = (1.2 - 9.8m)ĵ N

where m = mass of the ball

Magnitude of the resultant force = (9.8m - 1.2) N

Since the weight of the ball is expected to exceed the air resistance (because the ball is falling vertically downwards), the direction of the resultant force is vertically downwards. Its unit is Newtons, the SI unit of Force.

Explanation:

If a ball is falling vertically downwards, the only two forces acting on the ball include the weight of the ball (the pull of gravity on the ball) and the air resistance on the ball.

Weight of the ball acts downwards and is given as mg. where m = mass of the ball and g is the acceleration due to gravity = 9.8 m/s²

W = mg = (9.8m) N

In vector form, W = (-9.8mĵ) N

The air resistance on the ball = 1.2 N, the air resistance acts in the direction opposite the motion of the ball, and since the ball is moving vertically downwards, the air resistance acts vertically upwards.

In vector form, the air resistance = (1.2ĵ) N

Hence, the resultant force acting on the ball is the vector sum of all the forces acting on the ball.

Resultant force = (-9.8mĵ) + (1.2ĵ)

= (1.2 - 9.8m)ĵ N

Since the weight of the ball is expected to exceed the air resistance (because the ball is falling vertically downwards), the direction of the resultant force is vertically downwards.

Hope this Helps!!!

Answer:

False

Explanation:

It is located in the little dipper whose stars are more faint.

Answer:

Torque by electric dipole = pEcos thita

Answer:

The answer is below

Explanation:

There are various reasons for a power station not to work at maximum output all the time. These includes technical constraints, such as

1.  Availability of the plant: sometimes the availability of generating plants may affect capacity factor, which may be caused due to plant part break down, or routine servicing.

2.   Economic reasons: the capacity factor of a generating plant can be affected due to the level of usage at peak performance, as the cost of running the plant at peak form may be expensive to maintain.

3.  Availability of the energy resource: this often applicable to generating plants using renewable energy, this is because, energy source such as wind, solar and water may not be readily available all the year round as they can be seasonal. Also, the maximum output can be affected even if the generating plant is using non renewable energy, as there maybe some times, unavailability or low supply of the crude oil or fossil fuel.

Also, the main reason in which the capacity factor for non-renewables is always higher than for renewables, is because of the availability factor, or availability of the energy resources. This is because renewable energy such as water, wind, and solar are not readily available all the time, and are subject to atmospheric conditions, unlike non renewable energy such as crude oil, which can be readily available by purchasing them.

Answer:

Henri’s wave and Geri’s wave have the same amplitude and the same energy

Explanation:

The amplitude of a wave is the distance between the midpoint and the trough (or the crest). This is equivalent to half the distance between the trough and the crest. Therefore:

The energy of a wave is directly proportional to its amplitude.

Answer:

its letter b

Explanation:

Answer:

The substances which allow an electric current to pass through it is called conductors.

Example: Metals like copper,iron ,graphite etc.

The substances which do not allow the electric current to pass through is called Insulators.

Example: Glass, dry wood ,plastic etc.

Hope this helps...

Good luck on your assignment...

Answer:

400grams

Explanation:

Mass is density × volume

0.5×800= 400 grams

Mass is density × volume

0.5×800= 400 grams.

Density is the number of things—which could be people, animals, plants, or objects—in a certain area. To calculate density, you divide the number of objects by the measurement of the area. The population density of a country is the number of people in that country divided by the area in square kilometers or miles.

density, the mass of a unit volume of a material substance. The formula for density is d = M/V, where d is density, M is mass, and V is volume.

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Answer: There will be 75258 nuclei left at 6 pm.

Explanation:

a) half-life of the radioactive substance:

Half life is the amount of time taken by a radioactive material to decay to half of its original value.

[tex]t_{\frac{1}{2}}=\frac{0.69}{k}[/tex]

[tex]k=\frac{0.69}{t_{\frac{1}{2}}}=\frac{0.693}{2hours}=0.346hours^{-1}[/tex]

b) Expression for rate law for first order kinetics is given by:

[tex]A=A_0e^{-kt}[/tex]

where,

k = rate constant  

t = time for decomposition = 6 hours ( from 12 noon to 6 pm)

A = activity at time t = ?

[tex]A_0[/tex] = initial activity  = 600, 000

[tex]A=600000\times e^{-0.346\times 6}[/tex]

[tex]A=75258[/tex]

Thus there will be 75258 nuclei left at 6 pm.

Answer:

a 1.26 km b 10.5 m/s

Explanation:

A. Distance travelled by the schooterist

Since the schooterist travels in a circular path, the distance moved is the circumference of a circle, C with radius r = 0.2 km

C = 2πr

= 2π(0.2 km)

= 1.26 km

So, the distance travelled by the schooterist is 1.26 km

B. The velocity of the schooterist

The velocity of the schooterist v = distance travelled/time

distance travelled = 1.26 km = 1260 m

time = 2 minutes = 2 × 60 s = 120 s

So, V = 1260 m/120 s

= 10.5 m/s

So, the velocity of the schooterist is 10.5 m/s

Answer:

Total contraction on the Bar  = 1.22786 mm

Explanation:

Given that:

Total Length for aluminum bar = 600 mm  

Diameter for aluminum bar  = 40 mm

Hole diameter  = 30 mm

Hole length = 100 mm

elasticity for the aluminum is 85GN/m² = 85 × 10³ N/mm²

compressive load P = 180 KN = 180  × 10³ N

Calculate the total contraction on the bar = ???

The relation used in  calculating the contraction on the bar is:

[tex]\delta L = \dfrac{P *L }{A*E}[/tex]

The relation used in  calculating the total contraction on the bar can be expressed as :

Total contraction in the Bar = (contraction in part of bar without hole + contraction in part of bar with hole)

i.e

Total contraction on the Bar = [tex]\dfrac{P *L_1 }{A_1*E} + \dfrac{P *L_2 }{A_2 *E}[/tex]

Let's find the area of cross section without the hole and with the hole

Area of cross section without the hole is :

Using A = πd²/4

A = π (40)²/4

A = 1256.64 mm²

Area of cross section with the hole is :

A = π (40²-30²)/4

A = 549.78 mm²

Total contraction on the Bar = [tex]\dfrac{P *L_1 }{A_1*E} + \dfrac{P *L_2 }{A_2 *E}[/tex]

Total contraction on the Bar  = [tex]\dfrac{180 *10^3 \N }{85*10^3 \ N/mm^2} [\dfrac{500}{1256.64}+ \dfrac{100}{549.78}][/tex]

Total contraction on the Bar  = 2.117( 0.398 + 0.182)

Total contraction on the Bar  = 2.117*(0.58)

Total contraction on the Bar  = 1.22786 mm

Answer:

Explanation:

ave speed is always (frequency) x (wavelength)

Speed  =  (450 /sec) x (0.52 m)

=      234 m/sec .

Answer:

The most of the elements in the periodic table are metals. The elements cannot be gases and liquids (Molecules are mainly gases and liquids). Metalloids are few. Examples (Germanium, Arsenic)

Answer:

So the weight of the body is 700N

Explanation:

mass of the object=70kg

force of gravity=10N/kg

weight of the object=w-?

as we know that

weight=mass × force of gravity

weight=70kg × 10N/kg

WEIGHT OF THE BODY=700N

I HOPE IT WILL HELP YOU

GOOD LUCK FOR THE ASSIGNMENT

The correct answer is 700 N.

Object mass = 70 kg

Gravity = 10N / kg

Weight = Mass x Gravity

Weight = 70kg x 10N / kg

Weight = 700 N

Mass is more basic because it is a unique property of the object. Weight varies from place to place depending on the acceleration of gravity. If the mass on the earth is m = 10kg, the weight is W = mg = 10 x 10 = 100N.

The strength of the Earth's gravitational field is 10 Newtons (N / kg) per kilogram. This means that there is a force of 10 Newtons per kilogram on Earth. Mass is the amount of substance that makes up an object.

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