We want to find the energy that we need to transform 2kg of ice at 0°C to water at 20°C.
We will find that we must give 840,000 Joules.
First, we must change of phase from ice to water.
We use the specific latent heat of fusion to do this, this quantity tells us the amount of energy that we need to transform 1 kg of ice into water.
So we need 336,000 J of energy to transform 1kg of ice into water, and there are 2kg of ice, then we need twice that amount of energy:
2*336,000 J = 672,000 J
Now we have 2kg of water at 0°C, and we need to increase its temperature to 20°C.
Here we use the specific heat, it tell us the amount of energy that we need to increase the temperature per mass of water by 1°C.
We know that:
specific heat of capacity of water = 4200 J/kg°C
This means that we need to give 4,200 Joules of energy to increase the temperature by 1°C of 1kg of water.
Then to increase 1°C of 2kg of water we need twice that amount:
2*4,200 J = 8,400 J
And that is for 1°C, we need to give that amount 20 times (to increase 20°C) this is:
20*8,400 J = 168,000 J
Then the total amount of energy that we must give is:
E = 672,000 J + 168,000 J = 840,000 J
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which statement accurately describes how the acceleration of an object in free fall changes
Answer:
A ball rolls off the table and free falls to the ground. Which statement accurately describes its acceleration? Its acceleration is downward but remains a constant value as it falls.
After release of jet, energy is lost by the engine. How principle of conservation of energy is obeyed in this condition.
Answer:
The principle of conservation of energy states that in a closed system, the energy can neither be created nor destroyed between interacting particles and remains constant or transformed from one form to another
In the jet engine, the release of jet changes the number of interacting particles in the engine, and given that energy cannot be created in the instantaneously closed system of the engine, energy is carried away and therefore lost by particles in the jet exhaust
The conservation of energy principle is therefore obeyed in the condition in which the jet engine losses energy by the release of jet
Explanation:
Which type of electromagnetic wave is deliberately used in some
circumstances to cause damage to living cells in the human body?
A. Infra-red
B. Gamma rays
C. Microwaves
D. Radio waves.
Gamma rays
used in radiotherapy
A man pulls his luggage on a 30 degree incline with a constant force of 25 N. How
much work does he do after walking 20.0 m?
a) 430 J
b) 330J
c) 1500J
d) 250 J
We know
[tex]\boxed{\sf W=Fscos\theta}[/tex]
[tex]\\ \sf\longmapsto W=25(20)cos30°[/tex]
[tex]\\ \sf\longmapsto W=500\times \dfrac{\sqrt{3}}{2}[/tex]
[tex]\\ \sf\longmapsto W=250\sqrt{3}[/tex]
[tex]\\ \sf\longmapsto W=250(1.73)[/tex]
[tex]\\ \sf\longmapsto W\approx 430J[/tex]
Option a) 430 J work done he do after walking 20.0 m.
What is work?Work, in physics, is a measure of energy transfer that happens when an object exists moved over a distance by an external force at least part of which exists involved in the direction of the displacement.
Displacement exists as the distance moved in a straight line, in a provided direction, from the starting point. Displacement exists as a vector quantity as it includes size and direction.
An angle stands the figure formed by two rays, named the sides of the angle, sharing a standard endpoint, named the vertex of the angle.
Force=F=25NDisplacement=s=20mAngle=30°⇒[tex]W=Fcos\theta[/tex]
⇒[tex]W=25(20)cos 30^{0}[/tex]
Then,
⇒[tex]W=50*\sqrt{3} /2[/tex]
⇒[tex]W=250\sqrt{3}[/tex]
Hence,
⇒[tex]W=250(1.73)[/tex]
[tex]W[/tex] approximately 430J.
Hence, Option a) 430 J work done he do after walking 20.0 m.
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A 5.41 kg ball is attached to the top of a vertical pole with a 2.37 m length of massless string. The ball is struck, causing it to revolve around the pole at a speed of 4.75 m/s in a horizontal circle with the string remaining taut. Calculate the angle θ, between 0∘ and 90∘, that the string makes with the pole. Use g=9.81 m/s2.
Answer:
θ = 66º
Explanation:
This exercise of Newton's second law must be solved in part, let's start by finding the slowing down acceleration of the ball
a = v² / r
the radius of the circle is
sin θ = r / L
r = L sin θ
we substitute
a = v² /L sin θ
now let's write Newton's second law
vertical axis
T_y -W = 0
T_y = W
radial axis
Tₓ = m a (1)
let's use trigonometry for the components of the string tension
cos θ = T_y / T
sin θ = Tₓ / T
Tₓ = T sin θ
we substitute in 1
T sin θ = [tex]\frac{m \ v^2}{L \ sin \theta}[/tex]
T L sin² θ = m v²
we write our system of equations
T cos θ = m g
T L sin ² tea = m v²
we divide the two equations
L [tex]\frac{sin^2 \theta}{cos \theta}[/tex] = v² / g
(1 -cos²)/ cos θ = [tex]\frac{v^2 }{g \ L}[/tex]
1 - cos² θ = [tex]\frac{4.75^2}{9.81 \ 2.37}[/tex] cos θ
cos² θ + 0.97044 cos θ -1 = 0
we change variable cos θ = x
x² + 0.97044 x - 1 =0
x= [tex]\frac{-0.97 \pm \sqrt{0.97^2 - 4 1} }{2}[/tex]
since the square root is imaginary there is no real solution to the problem, suppose that the radius is 1 m r = 1 m
T sin θ = [tex]\frac{m \ v^2}{ r}[/tex]
T cos θ = m g
resolved
tan θ = [tex]\frac{v^2}{ r g}[/tex]
θ = tan⁻¹ ( 4.75²/ 1 9.81)
θ = 66º
Which are characteristics of a prokaryotic cell? Select three options.
O contains DNA
O lacks DNA
O contains ribosomes
O lacks ribosomes
O contains a nucleus
O lacks a nucleus
I NEED THIS QUICKLY
Answer:
A. Contains DNA
C. Contains ribosomes
F. Lacks a nucleus
Explanation:
A long distance runner running a 5.0km track is pacing himself by running 4.5km at 9.0km/h and the rest at 12.5km/h. What is his average speed?
Answer:
9.26 km/h
Explanation:
Applying,
V' = D'/t'............... Equation 1
Where V' = Average speed, D' = Total distance, t' = total time.
Given: D' = 5 km
But,
v = d/t............ Equation 2
Where v = speed , d = distance, t = time
t = d/v............ Equation 3
Given: d = 4.5 km, v = 9 km/h, and d = 0.5 km, v = 12.5 km/h
Therefore,
t₁ = 4.5/9 = 0.5 hours
t₂ = 0.5/12.5
t₂ = 0.04 hours
Therefore,
V' = 5/(0.5+0.04)
V' = 5/0.54
V' = 9.26 km/h
Una partícula efectúa un MAS cuya ecuación es: x=0,3 cos (2t + /6) m. Determinar: Amplitud, frecuencia angular, fase inicial, periodo, frecuencia de oscilación y posición en t=0,25 s
Answer:
The answer is below
Explanation:
Una partícula efectúa un MAS cuya ecuación es: x=0.3cos (2t + π/6) m. Determinar: Amplitud, frecuencia angular, fase inicial, periodo, frecuencia de oscilación y posición en t=0.25 s
Solution:
La ecuación de la onda es:
x = A cos (ω t + Ф), donde:
A = amplitud, ω = frecuencia angular = 2 π / T = 2 π f, Ф = fase inicial, f = frecuencia, T = período
Por lo tanto, comparando la ecuación de la onda con x = 0.3cos (2t + π / 6), obtenemos:
a) A = 0.3
b) ω = 2 rad / s
c) Ф = π / 6 rad
d) ω = 2π / T
2 = 2π / T
T = 3.14 s
e) ω = 2πf
2 = 2πf
f = 0.32 Hz
f) en t = 0.25 s:
x (t) = 0.3cos (2 * 0.25 + π / 6) = 0.22 m
1. What type of VOM reading requires the meter to be placed in series with the circuit?
A. Resistance
B. Voltage
C. Current
O
D. Power
Answer:
C. Current.
Explanation:
In a series circuit the current is equal in all of its components, so to measure the current we put the meter in series with the circuit.
the diameter of circular park is 80 m find its area
Give reason.
b} String roller is an example of wheel and axel .Why?
Explanation:
string roller is called an example of wheel and axel because The thin rod which needs to be turned is called the axle and the wider object fixed to the axle, on which we apply force is called the wheel.
hence the we apply force on the roller and the string gets tight.
Wat is acceleration!!!!!
Answer:
Acceleration is the rate of change of velocity with time.its system international unit is meters per second square.
I hope this helps
what is velocity give its SI unit
Answer:
Velocity is the speed of something given in a direction. the SI unit of velocity is metre per second or m/s.
A water heater marked 4 kW takes 4 minutes to heat 1 kg of water from 20 °C to 50 °C. The cost of electrical energy per kWh
is $0.120. What will be the total cost of energy consumption?
The total cost of the energy consumption for the given time period is $0.0364
The given parameters include;
power rating of the heater, P = 4 kW = 4000 Wtime taken to completely boil the water,[tex]t = 4 \min = 4 \min \times \frac{1 \ h}{60 \ \min} = 0.067 \ h[/tex]mass of the water, m = 1 kginitial temperature of the water, t₁ = 20 ⁰Cfinal temperature of the water, t₂ = 50 ⁰Cspecific heat capacity of water, c = 4200 J/kg⁰Ccost of electrical energy = $0.12The total energy consumed in the process of heating the water;
Total electrical Energy = Energy of the heater (kWh) + Energy of the heated water (kWh)
Energy of the heater (kWh) = power x time
= 4 kW x 0.067 h
= 0.268 kWh
Energy of the heated water (J) = mcΔt
where;
Δt is the change in temperature = t₂ - t₁
= 50 ⁰C - 20 ⁰C = 30⁰C
Energy of the heated water (J) = 1 x 4200 x 30
= 126,000 J
Electrical power of the heated water (Watts) = [tex]\frac{126,000 \ J}{4 \ \min} \times \frac{1 \min}{60 \ s} = 525 \ W[/tex]
Energy of the heated water (kWh) = [tex]\frac{525}{1000} \times 4\min\times \frac{1 \ hr}{60 \min} = 0.035 \ kWh[/tex]
Total electrical Energy = 0.268 kWh + 0.035 kWh
= 0.303 kWh
The total cost of the energy consumed is calculated as;
[tex]Total \ cost = \frac{\$ \ 0.12}{kWh} \times 0.303 \ kWh = \$ \ 0.0364[/tex]
Therefore, the total cost of the energy consumption is $0.0364
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A converging lens of focal length 20cm, forms a real image twice the size of the object. Calculate:
i) the power of the lens;
ii) the position of the image.
Answer:
Solition given:
focal length(f)=20cm
size of image(v)=2x
size of object(u)=x
we have
power of lens= reciprocal to focal length=1/20=0.05/cm
ii.
the position of the image is beyond C.
Explanation:
See the attachment !!!!!!!
What will happen to the velocity and momentum of each ball when the small ball hits the heavier large ball?
The small ball will transfer its momentum to the heavier ball. Since the momentum gets conserved. The velocity will depend upon the mass of the balls.
What is the law of conservation of momentum?According to the law of conservation of momentum. The momentum of the body before the collision is always equal to the momentum of the body after the collision.
The momentum of the body is given by the product of the mass and velocity of the body.
According to the law of conservation of momentum
Momentum before collision =Momentum after collision
Hence the small ball will transfer its momentum to the heavier ball.
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Why are road accidents at high speeds very much worse than road accidents at low speeds?
Answer:
The momentum makes it worse.
Explanation:
The momentum of vehicles running at faster speeds is very high and causes a lot of damage to the vehicles.
which is not a common theory on how the effects of hypnosis occurs
Answer:
EFFECTS Adverse reactions to hypnosis are rare, but may include: Headache. Drowsiness. Dizziness
A skipper on a boat notices wave crests passing his anchor chain every 5.6 s . He estimates the distance between wave crests to be 16 m . He also correctly estimates the speed of the waves. Find this speed.
Answer:
v = 2.85 m/s
Explanation:
Given that,
A skipper on a boat notices wave crests passing his anchor chain every 5.6 s.
The distance between wave crests to be 16 m.
We need to find the speed of the waves. The speed of a wave can be calculated by the formula as follows :
[tex]v=f\lambda\\\\v=\dfrac{\lambda}{T}\\\\v=\dfrac{16}{5.6}\\\\v=2.85\ m/s[/tex]
So, the speed of the wave is 2.85 m/s.
Guys please help this is very important it would be greatly appreciated if you would add the work. Thank you !!
Answer:
enjoy
Explanation:
The number of time a cricket chirps in a minute is a function of the temperature in the formula: n=4t-160, where n=number of times a cricket chirps a minute and t=temperature in farenheit. You can use the temperature t=(1/4)n+40 to estimate the temperature based on the number of chirps per minute.
byeeeeeeeeeeeejdiiwidjwdjj2xi2idiwidisididie
Answer:
Be serious or else CEO of brainly will kick you out
3 write the three laws given by kepler.How did they help Newton to arrive at the inverse square law of gravity?
Answer:
Kepler's laws apply: First Law: Planetary orbits are elliptical with the sun at a focus. Second Law: The radius vector from the sun to a planet sweeps equal areas in equal times. Third Law: The ratio of the square of the period of revolution and the cube of the ellipse semimajor axis is the same for all planets.
1.Convert 340 cm into m *(answer=0.34m)
2.What is the weight of potatoes of mass 75kg on the surface of the earth? *(ans=735 N)
[g=9.8 m/s^2
[g=9.8 m/s^2]
3.The weight of body is 420 N.Calculate its mass. *(42.857 kg)*
Answers are all given so i just need the process please (i will mark you brainliest please..
Answer:
1.for the first one 100centimeters make 1 meter therefore
100cm-1m
340cm-x
340/100
=3.4
the answer is supposed to be 3.4, maybe there's a mistake with the question or the answer
2.the weight of a body is given by the formula
mass×gravity,in this case the mass is 75kg and the gravity is 9.8
weight=75×9.8
=735N
3.for this one the mass of a body is given by the formula
mass=weight/gravity
=420/9.8
=42.8kg
I hope this helps
any correct ans guess for 30 pts and brainlist
Answer:
a) ii
b) i
c)iii
d)iii
e) i
f)iii
Explanation:
i hope this will help
Answer:
the answer of b is N and d is mol
Observe the given figure and find the the gravitational force between m1 and m2.
Answer:
The gravitational force between m₁ and m₂, is approximately 1.06789 × 10⁻⁶ N
Explanation:
The details of the given masses having gravitational attractive force between them are;
m₁ = 20 kg, r₁ = 10 cm = 0.1 m, m₂ = 50 kg, and r₂ = 15 cm = 0.15 m
The gravitational force between m₁ and m₂ is given by Newton's Law of gravitation as follows;
[tex]F =G \cdot \dfrac{m_{1} \cdot m_{2}}{r^{2}}[/tex]
Where;
F = The gravitational force between m₁ and m₂
G = The universal gravitational constant = 6.67430 × 10⁻¹¹ N·m²/kg²
r₂ = 0.1 m + 0.15 m = 0.25 m
Therefore, we have;
[tex]F = 6.67430 \times 10^{-11} \ N \cdot m^2/kg \times \dfrac{20 \ kg\times 50 \ kg}{(0.1 \ m+ 0.15 \ m)^{2}} \approx 1.06789 \times 10^{-6} \ N[/tex]
The gravitational force between m₁ and m₂, F ≈ 1.06789 × 10⁻⁶ N
Answer the following questions 1 What is the difference between mass and weight of an object. Will the mass and weight of an object on the earth be same as their values on Mars ? Why?
Answer:
difference between mass and weight is that mass is amount of matter in a material while weight is a measure of how the force of gravity acts upon that mass.the mass of an object will be same on earth and mars but its weight on both planets will be different.
A compound eye __________. ANSWER Unselected is composed of thousands of prisms that focus light onto only a few photoreceptor cells Unselected All of the listed responses are correct. Unselected works best for resolving stationary images Unselected contains many individual light detectors, each with its own lens Unselected is possessed only by insect
Answer:
contains many individual light detectors, each with its own lens
Explanation:
The compound eye is found mainly in insects and crustaceans, it is composed of individual receptor units, each with its focus, sensing nerve; each one gives a small image of the environment, so the image is mosaic type, not a complete integral image of the environment.
When reviewing the different statements, the correct one is
contains many individual light detectors, each with its own lens
A car travels first 10 km in 20 minutes and another 10 km in 30 minutes. What is the average speed of the car in m/s?
Total distance = 10 km + 10 km = 20 km
1 km = 1000 m
20km x 1000 = 20,000 m
Total time = 20 min. + 30 min. = 50 minutes
Average speed = Distance / time
Average speed = 20,000/50 min
Average speed = 400 m/s
beansFe(aq) + Al(s) → beansAl(aq) + Fe(s) (7 points) a. What type of reaction is this? Explain what you think happened.b. This is also another type of reaction. What is it? Give another common example of this type of reaction.c. Do you think it is OK to eat the green beans? Explain why, or why not.
Answer:
tôi đoán lagf pjhAWN ỨNG HÓA HỌC
Explanation:
A person slaps her leg with her hand, which results in her hand coming to rest in a time interval of 2.25 ms2.25 ms from an initial speed of 4.25 m/s4.25 m/s . What is the magnitude of the average contact force exerted on the leg, assuming the total mass of the hand and the forearm to be 1.75 kg1.75 kg
Answer:
The force is 3305.6 N.
Explanation:
Final velocity, v = 0
time, t = 2.25 ms
initial velocity, u = 4.25 m/s
mass, m = 1.75 kg
Let the acceleration is a.
Use first equation of motion.
v = u + a t
0 = 4.25 + a x 0.00225
a = - 1888.9 m/s^2
The force is
F = ma
F = 1.75 x 1888.9
F = 3305.6 N
