Answer:
50km/h
Explanation:
Average Speed = Distance/Time
100km/2h = 50km/h
An astronaut wearing a space suit floats in the middle of a room with no air (i.e. vacuum) and is 20.0 m from any wall, the floor and the ceiling. She needs to get to the door so she can go with her NASA friends to eat a hamburger. She has only a book and a pencil in her possession. She cannot call for help since something is interfering with her signal. Under these conditions, how can she get to the door
Answer:
To get to the door, the astronaut has to throw the book and pencil away from her in the direction opposite to that of the door.
Explanation:
Since no net force acts on her and she floats in the center of the room, if she throws the book and pencil away from her, since both her, the book and the pencil have an initial momentum p = 0, and since momentum is conserved, then after throwing the book and pencil away from her, the momentum of both her, the book and pencil is still zero.
The astronaut will thus develop a momentum which is opposite to that of the book and pencil. This is shown below.
Since p = p' where p = initial momentum of astronaut, book and pencil = 0 and p' = final momentum of astronaut, book and pencil = mv + m'v' where m = mass of book and pencil, v = velocity of book and pencil, m' = mass of astronaut and v' = velocity of astronaut.
So, p = p'
0 = mv + m'v'
mv = -m'v' where mv = momentum of book and pencil and m'v' = momentum of astronaut
v' = -mv/m
We see that the astronaut develops a momentum opposite in direction but equal in magnitude to that of the book and pencil and will thus develop a velocity opposite to that of the book and pencil.
Thus, to get to the door, the astronaut has to throw the book and pencil away from her in the direction opposite to that of the door.
Which of the following statements is NOT correct?
A. If the forces on an object are balanced, then the object can be at a constant speed.
B. If the forces on an object are balanced, then the object can be at rest.
C. If the forces on an object are unbalanced, then the object can be accelerating.
D. If the forces on an object are unbalanced, then the object can be at rest.
Select the correct answer. A truck moves 60 kilometers east from point A to point B. At point B, it turns back west and stops 15 kilometers away from point A. What are the total distance and total displacement of the truck? A. The total distance is 105 kilometers, and the total displacement is 15 kilometers east. B. The total distance is 105 kilometers, and the total displacement is 45 kilometers east. C. The total distance is 60 kilometers, and the total displacement is 60 kilometers east. D. The total distance is 60 kilometers, and the total displacement is 45 kilometers east. E. The total distance is 105 kilometers, and the total displacement is 75 kilometers east.
Answer:
Option a
Explanation:
How efficient is a pulley system if an operator has to pull 2.5m of rope to lift a 250 N pail of water a distance of 4.5 m?
Answer:
the pulley system is very efficient
Explanation:
Given;
load, L = 250 N
distance moved by the load, a = 4.5 m
distance moved by the effort, e = 2.5 m
let the force or effort applied = F
Apply the principle of conservation of energy;
F x e = L x a
F = (L x a) / e
F = (250 x 4.5) / 2.5
F = 450 N
The efficient of the pulley system;
E = Output force / Input force
E = (450 x 2.5) / (250 x 4.5)
E = 1 = 100%
Therefore, the pulley system is very efficient
Water can exist in three states: solid (ice), liquid and gas (steam).In which state, or states, is the motion of the molecules only vibrational?
Answer:
solid
Explanation:
Answer:
In the solid state, the motion of molecules is only vibrational, because solids are very tightly packed together and cannot move other than by vibrating
HELP PLSSS I HAVE AN EXAM MONDAY AND I THINK THIS IS GONNA BE ON ITTTT
A fish is at the western bank of a river that is 64 m wide and has a current with a velocity of 0.90 m/s [S]. The fish swims directly across the river going due east. The fish can swim at a speed of 0.2 m/s.
a) How long does it take for the fish to get across the river
b) What is the resulting velocity of the fish
c) When the fish arrives on the opposite bank, how far is it from being at the point directly across from where it started?
The answers are here, please show work on how to get these
a) 3.2 x 10^2
b) 0.9 m/s (S 13 E)
c) 2.9 x 10^2
(a) 3.2 x 10²s
(b) 0.9 m/s (S 13 E)
(c) 2.9 x 10²m
Explanation:The sketch illustrating the scenario has been attached to this response.
As shown;
The fish swims due east with a velocity [tex]V_{x}[/tex] = 0.2m/s
The river current has a velocity [tex]V_{y}[/tex] due South = 0.9m/s
The resultant of the velocity is V
The width of the river is x = 64m
(a) To calculate how long it took the fish to get across the river, we know that velocity is the rate of change in distance, therefore we can use the relation;
V = [tex]\frac{d}{t}[/tex] -------------(i)
Where;
V = velocity of the fish = [tex]V_{x}[/tex] = 0.2m/s
d = distance from the start to the end = width of the river = x = 64m
t = time taken to move for that distance
Make t subject of the formula in equation (i);
t = [tex]\frac{d}{V}[/tex]
Substitute the values of d and V into the equation;
t = [tex]\frac{64m}{0.2m/s}[/tex]
t = 320 s
t = 3.20 x 10²s
Therefore, the time taken for the fish to get across the river is 3.20 x 10²s
(b) The resulting vector of the fish is V whose magnitude is the algebraic sum of vectors [tex]V_{x}[/tex] and [tex]V_{y}[/tex], and direction is given by θ. i.e
The magnitude of the resulting vector is;
|V| = [tex]\sqrt{(V_x)^2 + (V_y)^2}[/tex]
|V| = [tex]\sqrt{(0.2)^2 + (0.9)^2}[/tex]
|V| = [tex]\sqrt{(0.04) + (0.81)}[/tex]
|V| = [tex]\sqrt{(0.85)}[/tex]
|V| = 0.92m/s
|V| ≅ 0.9m/s
The direction of the resulting vector θ and is given by;
tan θ = [tex]\frac{V_y}{V_x}[/tex]
tan θ = [tex]\frac{0.9}{0.2}[/tex]
tan θ = 4.5
θ = tan⁻¹ ( 4.5)
θ = 77.47° South of East.
θ ≈ 77.5° South of East.
Subtracting θ = 77.5° from 90° gives its value East of South
i.e
90 - 77.5 = 12.5° East of South
This can also be written as S12.5°E
Approximating to the nearest whole number gives S 13 E
Therefore, the resulting velocity of the fish is 0.9m/s in the direction S13°E
(c) When the fish arrives on the opposite bank, its distance from being at the point directly across from where it started is the product of the velocity of the river current and the time taken by the fish to get across the river. This point is equivalent to k as shown in the diagram.
Therefore;
distance = velocity of river current x time taken
distance = 0.9m/s x 3.20 x 10²s
distance = 2.88 x 10²m
distance ≅ 2.9 x 10²m
Notice that the velocity of the river current is used since that's the velocity of the fish on the y-axis.
HELP ME ILL MARK YOU THE BRAINLIEST
Option C: Later in the day, less power is developed in lifting each box
Answer:
Later in the day, less power is developed in lifting each box.
power= workdone÷time
4) Describa una situación en la cual un cuerpo se encuentre en reposo para un observador, y en movimiento para otro.
Answer:
Rest and motion are the relative terms.
Explanation:
When the position of the object does not change with respect to time, the object is said to be at rest.
When the position of the object changes with respect to time, the object said to be in motion.
let there is a tree, the tree is at rest with respect to the person which is standing near by the tree.
But when the person is in outer space and able to see the tree, the tree is in motion as the earth is in motion.
A person sitting in the train which is moving is at rest when observed by the other person sitting in the train but he is in motion with respect to a person which is standing on the platform.
What are three methods of water conservation that we can do to protect our aquifers, watersheds, and ground water?
Answer:
• Go Native. Use native plants in your landscape. ...
• Reduce Chemical Use. Use fewer chemicals around your home and yard, and make sure to dispose of them properly - don't dump them on the ground!
• Manage Waste. ...
Explanation:
There are some easy ways to conserve water to help protect our aquifers, watersheds, and ground water. First, we can all conserve water, by not running the water while we brush our teeth and making sure we fix all leaking or dripping faucets. Another was to conserve water is to collect rain water to use to water your plants. Speaking of plants, you can also plant more zeroscape type landscapes that require less water. We can also update our shower heads and toilets to be low-flow and more efficient. Can't afford a new toilet? Simply add a brick to your tank and this will cut down on the water used for every flush.
Convert 162 km/h into m/s.
Answer:
45 m/s
Explanation:
162 / 3.6 = 45 m/s
Divide by 3.6 to convert km/h to m/s.
a petrol engine raises 200kg of water in well from a depth of 7m in 6s show that the engine is developed about 2.33 kw of power
Answer:
P = 2.33 kW
Explanation:
Given that,
Mass, m = 200 kg
It is raises in the well from a depth of 7 m in 6 s.
W e know that,
Power = work done/time
Put all the values,
[tex]P=\dfrac{mgh}{t}\\\\P=\dfrac{200\times 10\times 7}{6}\\\\P=2333.3\ W[/tex]
or
P = 2.33 kW
Hence, the power of the engine is 2.33 kW.
A cyclist is taking part in the Tour de France, which is a bicycle race that takes place every year.
a Two forces acting on the cyclist are weight and reaction. Name two other forces acting on him
as he cycles along.
the value of 'g' changes as per its position on the earth's surface.justify the statement
Answer:
PLEASE MARK ME AS A BRAINLIEST
Explanation:
There are slight variations in the value of g about earth's surface. These variations result from the varying density of the geologic structures below each specific surface location. They also result from the fact that the earth is not truly spherical; the earth's surface is further from its center at the equator than it is at the poles. This would result in larger g values at the poles. As one proceeds further from earth's surface - say into a location of orbit about the earth - the value of g changes still.
A spiral spring is compressed by 0.1cm. calculate the elastic potential energy in the spring if the stiffness of the spring is 100Nm^1
Answer:
[tex]E=5\times 10^{-5}\ J[/tex]
Explanation:
Given that,
A spring is compressed by 0.1 cm or 0.001 m
The spring constant of the spring, k = 100 N/m
The elastic potential energy in the spring is given by :
[tex]E=\dfrac{1}{2}kx^2\\\\E=\dfrac{1}{2}\times 100\times 0.001^2\\\\E=5\times 10^{-5}\ J[/tex]
So, the elastic potential energy of the spring is equal to [tex]5\times 10^{-5}\ J[/tex].
Resolver el siguiente problema usando los pasos de Pólya y la estrategia razón, proporción y porcentajes De los 240 viajeros que ocupan un avión, el 30% son asiáticos, el 15% africanos, el 25% americanos y el resto europeos. a) ¿Cuántos europeos viajan en el avión? b) ¿Cuál es el total de asiáticos y americanos que viajan en el avión? c) ¿Cuál es la razón de viajeros africanos a viajeros americanos?
Answer:
a) 72 europeos viajan en el avión, b) 132 pasajeros viajan en el avión, c) Hay una proporción de 3 africanos a 5 americanos en el avión.
Explanation:
a) Si 30 % son asiáticos, 15 % africanos y 25 % americanos, entonces 30 % son europeos. La cantidad de europeos en el avión es:
[tex]x = 0.3\cdot (240)[/tex]
[tex]x = 72[/tex]
72 europeos viajan en el avión.
b) El total de asiáticos y americanos en el avión se determina mediante la siguiente expresión:
[tex]x = (0.3 + 0.25)\cdot (240)[/tex]
[tex]x = 132[/tex]
132 pasajeros viajan en el avión.
c) En primer lugar, se calculan los números de africanos y americanos en el avión:
Africanos
[tex]x_{1} = 0.15\cdot (240)[/tex]
[tex]x_{1} = 36[/tex]
Americanos
[tex]x_{2} = 0.25\cdot (240)[/tex]
[tex]x_{2} = 60[/tex]
Y la razón de viajeros africanos a viajeros americanos es:
[tex]r = \frac{r_{1}}{r_{2}}[/tex]
[tex]r = \frac{36}{60}[/tex]
[tex]r = \frac{3}{5}[/tex]
Hay una proporción de 3 africanos a 5 americanos en el avión.
9) What is the temperature of 5 moles of nitrogen at 1 atm in a 2 liter container?*
- 4.88 K
- 0.0328 K
- 0.41 K.
- 0.0164 K
Answer:
4.88 K.
Explanation:
From the question given above, the following data were obtained:
Number of mole (n) = 5 moles
Pressure (P) = 1 atm
Volume (V) = 2 L
Gas constant (R) = 0.082 atm.L/Kmol
Temperature (T) =?
The temperature of the gas can be obtained by using the ideal gas equation as illustrated below:
PV = nRT
1 × 2 = 5 × 0.082 × T
2 = 0.41 × T
Divide both side by 0.41
T = 2 / 0.41
T = 4.88 K
Therefore, the temperature of the gas is 4.88 K.
Which one of the following is an example of a solution?
a. Sand particles in water
b. Orange Squash
c. Vinegar
d. Paint
Answer:
it is maybe A but i'm not 100% sure
Explanation:
its the only one that is mixed
Which circuit component usually acts as a switch or amplifier?
O A. A transistor
O B. A capacitor
O C. A resistor
D. A battery
Answer:
The answer is A. A transistor
Answer:
a transistor
Explanation:
A P E X
If an object's surface area is smaller does it create more or less pressure?
Answer:
When the surface area is less the pressure exerted by the object is more. However, when the surface area is large, the points of contact between the object and the pressure. Thus, less pressure is exerted by the body on the surface.Explanation:
hope it helpsIf the surface area of an object is smaller, it will create more pressure
An object's surface area is inversely proportional to its pressure.
This can be demonstrated from the formula below
Pressure:The can be defined as the perpendicular force acting per unit area. the S.I unit of pressure is N/m².
Formula:P = F/A.................. Equation 1Where: P = Pressure of the objectF = Force acting on the objectA = Surface area of the object.In View of the above equation, It can be seen that as the surface area of an object reduces the pressure created by the object will increase.
Hence, If the surface area of an object is smaller, it will create more pressure
Learn more about pressure here: https://brainly.com/question/25736513
An airplane is .68 Kilometers long. How many Millimeters long is the plane?
a. 680 mm
b. 6,800 mm
c. 68,000 mm
d. 680,000 mm
Given : Airplane is 0.68 kilometers long
We know that :
⊕ 1 km = 1000 meters
⊕ 1 m = 1000 millimeters
⇒ 1 km = (1000 × 1000) millimeters
⇒ 0.68 km = (0.68 × 1000 × 1000) millimeters
⇒ 0.68 km = 680,000 millimeters
Answer: Airplane is 680,000 millimeters long
If an airplane is 0.68 Kilometers long, the length of the airplane in millimeters would be 680000 Millimeters, therefore the correct answer is option D.
What is a unit of measurement?A unit of measurement is a specified magnitude of a quantity that is established and used as a standard for measuring other quantities of the same kind.
As given in the problem, If an airplane is 0.68 Kilometers long, then we have to find out the length of the airplane in millimeters,
1 kilometers = 1000 meters
1 meter = 100 centimeters
1 centimeters = 10 millieters
As given the length of the plane is 0.68 Kilometers.
0.68 kilometers = 680 meters
0.68 kilometers = 680×100 centimeters
0.68 kilometers = 680×100×10 millimeters
= 680,000 millimeters
Thus, the correct answer is option C.
To learn more about the unit of measurement from here, refer to the link;
brainly.com/question/12629581
#SPJ2
As a train starts from rest then accelerates down the track, coming toward an observer faster and faster, the frequency of the sound waves coming toward the observer will be
Answer:
Increase in frequency constantly
Explanation:
This concept can be explained by Doppler shift as per which any form of disturbance spreads out spherically from its point of origin. If the source of sound wave is stationary and the receiver is also stationary, then the frequency remains the same but if the source is moving, then the disturbance caused is closer on one side and distant on the other side thereby producing shorter wavelength in direction the source is moving and longer wavelength in the opposite direction.
Whats this i give 13 points
Answer:
pretty sure its A hope this helped
Which term is the product of force and distance?
power
work
net force
acceleration
Answer:
work
Explanation:
it is a scalar quantity. it is equal to product of force and distance if the direction of motion is in direction of force in straight line
Answer:
work
Explanation:
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Convection currents are the rising and sinking of warmer and cooler materials due to their densities. Why does the warmer magma do this?
Answer:
See Explanation
Explanation:
Convection is a mode of heat transfer which involves the actual movement of the particles of a substance.
The hotter particles move upwards and are replaced by the cooler particles, thus a convection current is set up. This is due to the fact that cooler particles are denser than warmer particles.
Warm magma is found far beneath the earth. It rises to the surface due to convection current thereby leading to volcanos. Volcanic eruptions result from convection currents that occur underground.
Please help ASAP
у.
B
C
Position (m)
A А
0
1
2
3
4
5
6
7
8
9
10
11
12
Time (s)
The graph describes the motion of an object.
The object moves with
from A to B. It
from B to C. It moves
from C to D.
Answer:
a10
Explanation:
4. A cell membrane contains all of the following EXCEPT:*
O glycolipids
phospholipids
sphingolipids
steroids
none of the above
Answer:
The correct answer is - none of the above.
Explanation:
Cell membranes or plasma membranes of the cell are composed mainly of fatty-acid-based lipids and proteins. Membrane lipids are of two types majorly, glucolipids, phospholipids, and sterols (generally cholesterol).
Sphingolipids are also a structural component of the cell membrane that helps in segregation into distinct membrane domains. Glycolipids are present on the surface of the plasma membrane.
Un objeto de masa de 250 g es arrastrado sobre una superficie con una velocidad de 25 m/s. Determina la energía cinética que pose
→ Energía cinética
Ecuación[tex]\large {\boxed {\bf E_c = \cfrac{mv^2}{2} }}[/tex]
La energía cinética de la masa se da en kilogramos, por lo que tendremos que convertir gramos a kilogramos...
[tex]\large {\text {$ \blue {\sf 250 g \rightarrow 0,25 kg }$}}[/tex]
Entonces tendremos:[tex]\large {\text {$ \purple {\sf E_c = \cfrac{ 0,25 \cdot 25 }{2} \rightarrow \quad \cfrac{6,25}{2} = 3,125} $}}[/tex]
[tex]\large {\boxed {\boxed {\boxed {\bf E_c = 3,125 }}}}[/tex]
A gas in a sealed container has a pressure of 50 kPa at 27°C. What will the pressure of the gas be if the temperature rises to 87°C?
Answer:
the final pressure of the gas is 60 kPa.
Explanation:
Given;
initial pressure of the gas, P₁ = 50 kPa = 50,000 Pa
initial temperature of the gas, T₁ = 27⁰ C = 27 + 273 = 300 k
final temperature of the gas, T₂ = 87⁰ C = 87 + 273 = 360 K
Let the final pressure of the gas = P₂
Apply pressure law;
[tex]\frac{P_1}{T_1} = \frac{P_2}{T_2} \\\\P_2 = \frac{P_1T_2}{T_1} = \frac{50,000 \times 360}{300} = 60,000 \ Pa = 60 \ kPa[/tex]
Therefore, the final pressure of the gas is 60 kPa.
A certain capacitor, in series with a resistor, is being charged. At the end of 25 ms its charge is half the final value. The time constant for the process is about:
Answer:
τ = 36 10⁻³ s
Explanation:
The charge of a circuit Rc is given by the expression
q = q₀ (1 - [tex]e^{-t/ \tau }[/tex])
q / q₀ = 1 - e^{-t/ \tau }
in this exercise they indicate that
q / q₀ = ½
for a time t = 25 10⁻³ s
we substitute
½ = 1 - [tex]e^{- 25 \ 10^{-3} / \tau}[/tex]
e^{- 25 \ 10^{-3} / \tau} = 1 -½
- 25 10⁻³ /τ = ln 0.5
-25 10⁻³ / ln 0.5 = τ
τ = 36 10⁻³ s
Which statement best compares potential and kinetic energy?
O Objects always have more potential energy than kinetic energy.
O Kinetic energy increases and potential energy decreases when the velocity of an object increases.
O Only potential energy decreases when an object's height increases.
O Objects always have more kinetic energy than potential energy.
Mark this and return
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Answer:
B . Kinetic energy increases and potential energy decreases when the velocity of an object increases.
Explanation:
The statement with best compares potential energy and kinetic energy is that only kinetic energy increases when the velocity of the object increases.