Answer:
It is correct to say that if the human race continues to use energy as it is now, without change, we will witness negative environmental impacts around the world in this century.
As a concrete example, we can cite the means of transport that use fossil fuels, such as cars and buses, which release polluting gases into the atmospheric layer and cause the greenhouse effect, contributing to global warming.
To solve these problems, it is necessary to raise the awareness of individuals, so that there is more and more interest and search for environmentally responsible solutions, such as the large-scale production of electric cars, which do not pollute the environment.
A washing machine heats 10kg of water in each wash cycle. How much energy is saved by washing at 30'c instead of 50'c if the starting temperature of the cold water is 16'c? The specific heat capacity of water is 4200 J/Kg'c
Answer:
[tex]8.4 \times 10^{5}\; \rm J[/tex], assuming that there's no heat exchange between the washing machine and the environment.
Explanation:
Let [tex]m[/tex] denote the mass of water and [tex]c[/tex] the specific heat capacity of water. The energy required to raise the temperature of that much water by [tex]\Delta T[/tex] would be:
[tex]Q = c \cdot m \cdot \Delta T[/tex].
Washing at [tex]30\; \rm ^{\circ} C[/tex] would require a temperature change of [tex]\Delta T = 30\; \rm ^{\circ} C - 16\; ^{\circ} \rm C = 14\; \rm K[/tex].
Washing at [tex]50\; \rm ^{\circ} C[/tex] would require a temperature change of [tex]\Delta T = 50\; \rm ^{\circ} C - 16\; ^{\circ} \rm C = 34\; \rm K[/tex].
In both situations, [tex]c = 4.2 \times 10^{3}\; \rm J \cdot kg \cdot K^{-1}[/tex] while [tex]m = 10\; \rm kg[/tex].
Calculate the energy required in either situation:
Washing at [tex]30\; \rm ^{\circ} C[/tex]:
[tex]\begin{aligned}& Q({30\; ^{\circ} {\rm C}}) \\ &= c \cdot m \cdot \Delta T \\ &= 4.2 \times 10^{3}\; \rm J \cdot kg \cdot K^{-1} \times 10\; \rm kg \times 14\; \rm K \\ &= 588000 \times 10^{5}\; \rm J\end{aligned}[/tex].
Washing at [tex]50\; ^{\circ} {\rm C}[/tex]:
[tex]\begin{aligned}& Q({50\; ^{\circ} {\rm C}}) \\ &= c \cdot m \cdot \Delta T \\ &= 4.2 \times 10^{3}\; \rm J \cdot kg \cdot K^{-1} \times 10\; \rm kg \times 34\; \rm K \\ &= 1428000 \; \rm J\end{aligned}[/tex].
[tex]1428000\; \rm J - 588000\; \rm J = 8.4 \times 10^{5}\; \rm J[/tex].
Một người đi xe ô tô từ a đến b cách nhau 90km trong nửa quãng đường đầu người dó đi với vận tốc v1 trong nửa quãng đường sau người đó đi với vận tốc v2=2v1/3.Tính vận tốc của người đó trên mỗi chặng đường để sau 1.5h người đó đi đến b
Answer:
The speed of the first half is 75 km/h and for the second half is 50 km/h.
Explanation:
A person driving a car from a to b 90km apart for the first half of the distance travels with speed v1 the second half of the distance travels with a speed of v2=2v1/3. Calculate his speed per each the distance so that after 1.5 hours that person reaches b
Total distance, D = 90 km
Let the time for he first half is t and for the second half is t'.
Distance = speed x time
45 = v1 x t .... (1)
And
45 = v2 x t' .... (2)
Total time is T = t + t'
[tex]1.5 = \frac{45}{v_1}+\frac{45}{v_2}\\\\1.5 = \frac{45}{v_1}+\frac{3\times 45}{2v_1}\\\\1.5 = \frac{90+135}{2v_1}\\\\3v_1 = 225 \\\\v_1 = 75 km/h[/tex]
Now, v2 = 2 x 75/3 = 50 km/h
20. A semiconductor is a
crystalline solid that conducts current under any condition
metallic solid that conducts current under any condition
metallic solid that conducts current under certain conditions
crystalline solid that conducts current under certain conditions
Answer:
D. crystalline solid that conducts current under certain conditions
Explanation:
Semiconductors are crystalline solids that has the ability to conduct electrical currents but on certain conditions e.g heat. The conduction of semiconductors is less than that of conductors (metals) but more than insulators (nonmetals), hence, they are said to be intermediates of conductors and insulators in terms of electrical conductivity.
Examples of semiconductors are silicon, boron, carbon, germanium, arsenic etc.
Choose the option that best suit the question .
An inclined plane of angle Ɵ, acting as a simple machine has a velocity ratio :
(a) sinƟ
(b) 1/sinƟ
(c) cosƟ
(d) 1/cosƟ
(e) sinƟcosƟ
Answer:
(b) 1/sinƟ
Explanation:
A simple machine can be defined as a type of machine with no moving parts but can be used to perform work.
Basically, a simple machine allows for the transformation of energy into work. The six simple machines are; lever, wedge, pulley, screw, wheel and axle, and inclined plane.
Inclined plane is a simple machine set at an angle and then used to lift an object.
In Physics, the velocity ratio of a simple machine is calculated as a ratio of the distance moved by the effort to the vertical distance through which a load is raised.
Mathematically, the velocity ratio of an inclined plane of angle Ɵ, acting as a simple machine is given by the formula;
Velocity ratio (V.R) = 1/sinƟ
Basically, an increase in the angle of inclination (measured in degrees) of an inclined plane increases its velocity ratio.
Given that on Earth, gravity causes an acceleration of 9.8 m/s2, what is an acceleration of 7 g?
Answer:
68.6 m/s^2
Explanation:
1 g = 9.8 m/s^2
so
7 g × 9.8m/s^2 = 68.6
use the particle model to explain why the water expands
Answer:
Take water as an example; the size, shape and chemical composition of the water particles remains the same whether it is solid water (ice) or gaseous water (steam) - but how those particles move and are arranged is different for
A cyclist competes half round of a circular track of a diameter 636m in 1.5 minutes . find the velocity
Answer:
Given information:-
Radius of the circular track is 636 mThe time elapsed in the journey is 1.5 min or 90 sThe distance traveled by the cyclist is semi circumference of the circle = πr[tex]\clubsuit[/tex]The displacement of the cyclist will be shortest distance from his initial to final positions which is nothing but diameter of the circle = 2r
We know that,
[tex] \underline{ \boxed{ \sf{Speed = \frac{Distance \: covered }{Time \: taken}}}}[/tex]
[tex]\longrightarrow \sf{\frac{636 \times 3.14 m}{90s}} \\ \\ \longrightarrow \sf22.18 m/s[/tex]
Speed of the cyclist is 22.18 m/s[tex]\sf{Velocity = \frac{Displacement }{ Time} }[/tex]
[tex]\longrightarrow \sf{ \frac{2 \times 636m}{90s} } \\ \\ \longrightarrow \sf{14.13 \: m/s}[/tex]
Velocity of the cyclist is 14.13 m/sThank You :)
An instructor wishes to determine the wavelength of the light in a laser beam. To do so, he directs the beam toward a partition with two tiny slits separated by 0.195 mm. An interference pattern appears on a screen that lies 5.10 m from the slit pair. The instructor's measurements show that two adjacent bright interference fringes lie 1.55 cm apart on the screen. What is the laser's wavelength (in nm)
Answer:
λ = 610.6 nm
Explanation:
We are given;
Separation distance; d = 0.195 mm = 0.195 × 10^(-3) m
Interference pattern distance; D = 4.95 m
Width of the two adjacent bright interference; β = 1.55 cm = 1.55 × 10^(-2) m
Formula for the Fringe width is;
β = Dλ/d
Where;
λ is laser's wavelength
Thus;
λ = (d × β)/(D)
λ = (0.195 × 10^(-3) × 1.55 × 10^(-2))/4.95
λ = 610.6 × 10^(-9) m
λ = 610.6 nm
A 4000 N force acts on an object that initially has a momentum of 400 kg-m/s for 0.9 seconds. What is the final momentum of the system?
Answer:
4360 Kgm/s
Explanation:
Applying,
Ft = M-M'................. Equation 1
Where F = force, t = time, M = Final momentum, M' = Initial momentum.
make M the subject of the equation
M = Ft+M'............ Equation 2
From the question,
Given: F = 4000 N, t = 0.9 seconds, M' = 400 kg-m/s
Substitute these values into equation 2
M = 4000+(0.9×400)
M = 4000+360
M = 4360 kgm/s
Hence the final momentum is 4360 kgm/s
a bubble of gas rises to the surface of a soft drink. this is because
Si dejamos caer un objeto desde una gran altura, ¿será que tiene siempre la misma velocidad
Answer:
asdiieiwihebebwiwo3o2iwjw3
một oto đang chạy với vận tốc là 10m/s thì tăng tốc và chuyển động nhanh dần đều sau 20s thì đạt vận tốc 14m/s
a) tính gia tốc của xe
b) tính vận tốc xe sau 40s kể từ khi tăng tốc và quãng đường xe đi được trong thời gian đó
a) gia tốc = vf-vi / t
a = 14-10 / 20
a = 0,2ms⁻²
b) dưới dạng a = Δv / t
v = lúc
v = 0,2 × 40
v = 8ms⁻¹
như v = d / t
do đó d = vt
d = 8 × 40
d = 320m
hãy đánh dấu là trí óc nhất
physics as a subject involves measurement and estimation,giving examples of everyday life situations, explain the meaning and what is done in each case
Answer:
57
Explanation:
write any two uses of a wedge.
Answer: two uses of a wedge can be to tighten things as well as to lift things.
Explanation: because that is some things wedges (a mechanical tool) can do.
La resistencia de un termómetro de platino es de 6Ω a30°C. Hallar su valor correspondiente a 100°C,sabiendo que el coeficiente de temperatura de resistividad del platino vale 0,00392°C^(-1).
Respuesta:
7,6 Ω
Explicación:
Paso 1: Información dada
Resistencia a 30 °C (R₀): 6 ΩCoeficiente de temperatura (α): 0,00392 °C⁻¹Paso 2: Hallar la resistencia (R) a 100 °C
Podemos ver la relación entre la resistencia de un material y la temperatura usando la siguiente ecuación.
R = R₀ (1 + α × ΔT)
R = 6 Ω (1 + 0,00392 °C⁻¹ × (100 °C - 30 °C)) = 7,6 Ω
The first periodic table of elements Mendeleev created contained only 70 elements. True or false?
Explanation:
FALSE
The first periodic table of elements Mendeleev created contained 63 elements.
Angie walked a distance of 90 meters east in 70 seconds. What was her
velocity?
A. 0.78 m/s east
B. 1.3 m/s east
O C. 7 m/s east
D. 9 m/s east
Two children sitting on a see saw such that they can't swing.what is the net torque in this situation ??? Need an appropriate answer
Answer:
two childrens are sitting on a see saw but can't swing.it means both weight is same (a=b)
Explanation:
hope it will help u please mark me brillientAnswer:
which subject is that question
1. The hydrogen balloons which are used to collect weather information from the atmosphere is made of plastic and never completely filled. Thus the pressure inside and outside are same. The balloon is filled with 150 litres of hydrogen, the air temperature is 27°C and the atmospheric pressure is 98 kPa. The balloon rises to a height where it radios back that the pressure is 30kPa and the temperature is - 33°C. i. What is the Kelvin temperature equivalent to 27°C and -33°C? (1 mark) ii. What is the volume of hydrogen at this height? (2 marks)
Answer:
Answer:- Volume of the balloon is 5.78 L.
Solution:- There are 0.24 moles of hydrogen gas in a balloon at 35 degree C and 1.05 atm pressure. It asks to calculate the volume of the balloon.
This problem is based on ideal gas law equation:
P = 1.05 atm, n = 0.24 mole, T = 35 + 273 = 308 K
R =
V = ?
The equation could be rearranged for the volume as:
Let's plug in the values and do the calculations to get the volume of the balloon:
V = 5.78 L
So, the volume of the gas balloon is 5.78 L.
Annie has a soccer ball and a cake ball she kicks each ball with the same Force the soccer ball accelerates at 3 m per second squared and the kickball accelerates at 5 m per second squared use Newton's law to describe why the kickball has a greater acceleration
can someone pls help me calculate this?
Answer:
10N is the answerrrerreer
Answer:
f= 100N
Explanation: F=m×(v₀-vf/t)
=0.05ₓ(200-0/0.1)
=0.05ₓ2000
=100N
please mark as brainliest
how is speed different from velocity
Answer:
Speed is a time for how long an object is moving
Velocity is the direction of an object
Una rueda tiene 4 cm de diámetro y realiza
200 vueltas cada 5 minutos. Calcular:
a. la frecuencia
b. el período
c. la velocidad lineal o tangencial
d. La velocidad angular
e. La aceleración centrípeta.
Answer:
Una rueda tiene 4 cm de diametro y realiza 200 vueltas cada 4 minutos calcular a frecuencia b el periodo c la velocidad lineal l tangencial
diffusion in physics
Answer:
sorry but which class your talking 'bout
A 111 kg linebacker running at 1.9 m/s and a 82 kg quarterback running at 3 m/s have a head-on collision in midair. The linebacker grabs and holds onto the quarterback. (a) What is their combined speed immediately after the collision
Answer:
Explanation:
mass of linebacker, m = 111 kg
initial velocity, u = 1.9 m/s
mass of quarterback, m' = 82 kg
initial velocity, u' = 3 m/s
(a) Let they are moving in the same direction, the velocity is v after collision.
Use conservation of momentum
m u + m' u' = (m + m') v
111 x 1.9 + 82 x 3 = (111 + 82) v
v = 2.4 m/s
Let they are moving in opposite direction, the velocity is v after collision.
Use conservation of momentum
m u - m' u' = (m + m') v
111 x 1.9 - 82 x 3 = (111 + 82) v
v = - 0.18 m/s
a car of mass 500 kg travelling with a speed of 54km/hr is brought to rest over a distance of 40 m. find the acceleration and force applied on brakes
Answer:
Explanation:
[tex]a=\frac{v_f-v_0}{t}[/tex] We don't yet need the mass of the car, as we can see by this equation. What we do need is the velocity of the car, the initial velocity, in meters per second, and right now it's in km/hr. Not good. We need to convert. The conversion is as follows:
[tex]54\frac{km}{hr}*\frac{1000m}{1km}*\frac{1hr}{3600s}=15\frac{m}{s}[/tex] Ok, that's good. Now we have everything we need but the time element. If the car traveled a distance of 40 meters at 15 m/s, then we can use the d = rt equation to solve for t, and when we find t we plug it into the acceleration equation:
40 = 15t and
t = 2.7 seconds. The car traveled for 2.7 seconds to go that 40 meters. That's the only reason we were given the displacement. We need it for nothing else but that.
Filling in the acceleration equation now:
[tex]a=\frac{0-15}{2.7}=-5.6\frac{m}{s^2}[/tex] and the negative indicates we are in fact slowing down. That's the answer for the acceleration portion of the problem; now we need the force, F, applied to the brakes.
F = ma where m is mass (we get to use that value now!) and a is -5.6 m/s/s.
F = 500(-5.6) and
F = -2800 N and the negative here means that the force of the brakes is acting against the motion of the car: the brakes are pulling the car "backwards" to stop while the car's motion is forward. The negative indicates the direction the force is being applied.
Even though you praise your dog for sitting inside on his bed and chewing the bone you gave him, your dog insists on going outside and burying his bone. This is MOST likely an example of:
Answer:
dog
Explanation:
A motorcycle is moving at a constant velocity of 15 meters/second. Then it starts to accelerate and reaches a velocity of 24 meters/second in 3 seconds. What’s the acceleration of the motorcycle over this time? Use .
A.
9 m/s2
B.
8 m/s2
C.
6 m/s2
D.
5 m/s2
E.
3 m/s2
option E
3m/s square
hope it helped u
What's an area of the earth that suggest that " the Earth is like one giant jigsaw" idea could be true.
Which choice shows the correct sequence of features formed by continued wave erosion?
Answer:
Wave-cut cliff, sea arch, sea stacks
Explanation:
The effect of a wave erosion is made obvious by the structures formed by the wave action.
The high areas of land adjacent to the incoming wave develop the early features or the formation of wave action, which includes the wave-cut cliff
The continuous undercutting of the cliff by the wave results in the formation of the wave cut platform
The effect of the wave further on a cliff, results in the formation of a sea arch and finally a sea stack
Therefore, the correct sequence is the wave-cut cliff, sea arch, sea stacks
