Answer:
A mirror is an image reflecting an object.
Explanation:
yes a mirror is reflective
A mirror is a reflector of the wave. When light waves reflect the flat surface of a mirror, the same curvature and vergence are retained, in equal but opposite direction, by these waves as by the original waves.Coating a piece of glass on one side with glistening metals can convert the glass into a mirror that mirrors light. Window glass may reflect only 8% of the light, while mirrors can display 95% of the light. The glass in a mirror is generally covered in a silver or aluminum layer. dark material is placed on the back to prevent the tearing of the metal (reacting with the air and turning dull). The other side of the glass can be a mirror or a simple glass. This can be used to make windows easily visible, but difficult to view.Answer:
Explanation:
Yes, a mirror is reflective to light. But there are electro magnetic waves of different frequency like radio wave that a mirror is not reflective.
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1. A stone is thrown horizontally from a cliff 30m high with an initial speed of 20m/s. How far from the cliff does the stone strike the ground?
2. A ball rolls off the edge of a table 1.44m above the floor and strikes the floor at a point 2m horizontally from the edge of the table.
A) What is the time the ball was in the air?
B) What is the initial velocity of the ball?
3. A golfer hits a ball and gives it an initial velocity of 40 m/s, at an angle of 30º above the horizontal.
A) How long does the ball stay in the air?
B) How far horizontally (the range) does the ball travel before hitting the ground?
Answer:
1. The stone will strike the ground 49.46 m from the base of the cliff
2. A) Approximately 0.542 seconds
B) Approximately 3.69 m/s
3. A) The time the ball spends in the air is approximately 4.0775 s
B) The horizontal range is approximately 141.25 m.
Explanation:
1. The time it takes the stone to land is given by the equation, t = √(h/(1/2 × g)
∴ t = √(30/(1/2 × 9.81)) ≈ 2.473 seconds
The horizontal distance covered by the stone in that time = 20 × 2.473 ≈ 49.46 m
The stone will strike the ground 49.46 m from the base of the cliff
2. A) The time the ball spends in the air = t = √(h/(1/2 × g)
∴ t = √(1.44/(1/2 × 9.81)) ≈ 0.542 seconds
B) The initial horizontal velocity, u = Horizontal distance/(Time) = 2/0.542 ≈ 3.69 m/s
The initial horizontal velocity ≈ 3.69 m/s
3. A) The time the ball spends in the air is given by the following equation;
t = 2 × u × sin(θ)/g = 2 × 40 × sin(30)/9.81 ≈ 4.0775 s
t ≈ 4.0775 s
B) The horizontal range, R, of the ball is given by the equation for the range of a projectile as follows;
[tex]Range, R = \dfrac{u^2 \times sin (2 \cdot \theta) }{g}[/tex]
Substituting the known values, gives;
[tex]Range, R = \dfrac{40^2 \times sin (2 \times 30^{\circ}) }{9.81} \approx 141.25 \ m[/tex]
The horizontal range ≈ 141.25 m.
A 30 kg object has a frictional force of 60 N. It's coefficient of friction must be...?
A) 0.2
B) 2
C) .002
D) 20
mass = 30kg
frictional force = coefficient of friction * (mass * g)
g = 9.8 m/s^2
So:
60N = x * 294 N
x = 60 N / 294 N = 0,2
Ashley is flying a plane that has to reach a gradient of 360m/km in order to take off and not crash. Her goal is to travel from sea level to an elevation of 1000m at a distance of 2.8km. Calculate the gradient of Ashley’s flight and determine if she will crash!
Answer:
She is likely to crash because her flight gradient is lesser than the flight gradient required gradient to avoid crashing
Explanation:
The given parameters are;
The required gradient of the plane Ashley is flying needs to reach in order to take off and not crash = 360 m/km
The initial elevation of the plane Ashley is flying = Sea level = 0 m
The goal Ashley intends to make = Elevation of 1000 m at 2.8 km. distance
∴ Ashley's goal = Traveling from sea level to 1000 m at 2.8 km horizontal distance
We have;
The gradient = Rate of change of elevation/(Horizontal distance)
Therefore;
The gradient of Ashley's flight = (1000 - 0)/(2.8 - 0) = 357.143 m/km
The gradient of Ashley's flight ≈ 357.143 m/km which is lesser than the required 360 m/km in order to take off and not crash, therefore, she will crash.
to calculatw the power produced by a force, the size of the force must be known. What else needs to be known to calculate the power
-- The distance the force moved through
-- How long the force lasted
The other thing we need to calculate the power is the "Velocity".
A quantity of labor or work done to be accomplished within a particular period of timeframe is determined as power. It is denoted by "P".According to the given query, we are talking about the relation between Power and Force. Along with simple instances where such an item is moved at continuous speed by a constant force.
The relation can be shown as:
→ [tex]P= Fv[/tex]
where,
P = PowerF = Forcev = VelocityThus the above is the right response.
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What two things must you know to describe the motion of an object? __________________________________________________________________________
Distance is _________________________________________________________________
What is the displacement of a cyclist, who travels 1 mile north, then 1 mile east, and finally 1 mile south? ___________________________
Define speed ________________________________________________________________
How do speed and velocity differ? ______________________________________________
__________________________________________________________________________
How do velocities combine? In opposite directions? ________________________________ In the same direction? ________________________________________________________
A river flows at a velocity of 3 km/h relative to the riverbank. A boat moves upstream at a velocity of 15 km/h relative to the river. What is the velocity of the boat relative to the riverbank? ___________________________________
The rate at which velocity changes is called ________________________
True or false? Acceleration is the result of increases or decreases in speed.
A horse on a carousel that is moving at a constant speed is accelerating because _________________________________________________________________________
True or false? When the final velocity is less than the initial velocity of an object, the acceleration is negative.
The total distance traveled divided by the total time is _______________________
What are some common units for speed (give at least two) _____________ ___________
Define velocity ____________________________________________________________
Define acceleration _________________________________________________________
A quantity that has both magnitude and direction is called a _________________.
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On a distance-time graph speed is a ____________ line and thus a ____________ graph.
On a distance-time graph acceleration is a ___________ line and thus a _______________ graph.
Answer:
velocity is vector Quantity
Radio stations broadcast signals on two different frequency bands. These are called
Answer:
AM(amplitude modulation) and FM(frequency modulation)
Explanation:
A radio frequency band is a small adjacent section of the radio spectrum frequencies, whereby channels are usually used or set aside to be used.
They are usually of two different bands called AM which is known as amplitude modulation and FM which is known as frequency modulation
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Answer:
the last answer is correct.
Explanation:
If one team pulls with more force than the middle flag or marker will move
Two types of energy can be either kinetic or potential energy. Identify those two types. For each type, explain why it can be either kinetic or potential. -Help fast i have my test soon!
Answer:
All forms of energy are either kinetic or potential. The energy associated with motion is called kinetic energy . The energy associated with position is called potential energy . Potential energy is not "stored energy".
Explanation:
please help!!! give me a summary on why human population is either good or bad!! thank youu
Which TWO correctly relate the attraction between the particles of a liquid and the temperature at which the liquid changes state?
A. Strong attractions mean the liquid melts at a higher temperature
B. Strong attractions mean the liquid melts at a lower temperature
C. Strong attractions mean the liquid boils at a higher temperature
D. Strong attractions mean the liquid boils at a lower temperature
Answer:
a &c
Explanation:
>3
Attraction between the molecules of a liquid and the temperature at which the liquid changes state is "Strong attractions mean the liquid boils at a higher temperature". The correct option is C
What is Temperature ?Temperature is a physical quantity which measures hotness and coldness of a body. Temperature measures the degree of vibration of molecule in a body. Temperature is measured in centigrade (°C), Fahrenheit (°F) and Kelvin (K) in which Kelvin (K) is a SI unit of temperature. Absolute scale of temperature means Kelvin scale of temperature.
relation between Kelvin(K) and centigrade (°C),
°C= K - 273.15
from equation, 273.15 K means 0 °C, which is freezing point of water (ice).
when we give temperature to the body, its molecule or atom absorbs thermal energy and vibrate about their mean position. Amplitude of vibration get increases as we go on increasing temperature and for higher temperature force of attraction between molecules gets weaker. Hence for higher temperature, due to weaken the force of attraction between molecule, solid goes into liquid state. and further increase in temperature liquid goes into gaseous state.
Liquid has stronger force of attraction than gas and weaker than solid. Strong force of attraction means high temperature should be given to break molecular bonds. Therefore Strong attractions mean the liquid boils at a higher temperature.
Hence option C is correct.
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When the energy of a wave increases, what happens to the amplitude?
Answer:
The energy transported by a wave is directly proportional to the square of the amplitude. So whatever change occurs in the amplitude, the square of that effect impacts the energy. This means that a doubling of the amplitude results in a quadrupling of the energy.
Explanation:
When the energy of a wave increases, the amplitude also increases. This is because the amplitude of the wave is directly proportional to the energy of a wave.
What is the amplitude of a wave?The amplitude of a wave may be defined as the maximum displacement or distance moved by a point on a vibrating body or wave measured from its equilibrium position. It is equal to one-half the length of the vibration path.
It is the principle of physics that when the amplitude of the wave is higher, the energy also gets higher. To summarise, waves carry energy. The amount of energy they carry is related to their frequency and their amplitude. The higher the frequency, the more energy, and the higher the amplitude, the more energy.
Therefore, when the energy of a wave increases, the amplitude also increases. This is because the amplitude of the wave is directly proportional to the energy of a wave.
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Scientists have invented the equipment to harness the power of lighting for energy use. True or false
What are greenhouse gases? Can you name any?
Jen had an average speed of 2.5 m/s when hopping on one foot. If she hopped for 5.0 seconds, for what distance was she hopping?
Explanation:
distance
speed =_________
time
distance = speed × time
= 2.5 × 5.0
distance = 12.5 m
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Sometimes, I have to take my cat, Gigi, in the car. She doesn’t like this, and tends to hide under the couch when she knows she has to go. This means I have to drag her out. Assuming she is using her claws to try and stop me, identify the forces acting on Gigi, and draw a free body diagram for the situation. Make sure you label each force and identify where it’s coming from.
Answer:
F - fr = ma , N - W = 0
Explanation:
In this exercise we are asked to identify the forces that act on the jack, for this we will use Newton's second law
On the x axis
We have two forces: the friction and the force of the girl who pulls the cat
F - fr = ma
On the y axis
There are two forces: normal and weight
N - W = 0
A diagram of these forces can be seen in the attachment
1. In your own words explain what happens at a subduction zone. 2. In your own words explain what happens at a mid-ocean ridge. 3. At a subduction zone what causes magma to rise?
Answer:
1. The subduction zone serves as the meeting point for two tectonic plates.
2. At the Mid- Ocean ridge, decompression melting occurs.
3 What causes the magma to rise is the increase in pressure caused by collection of gases by the magma.
Explanation:
Subduction zone is define as a zone where tectonic plates ( an oceanic plate slides beneath a continental plate) meets and contributes to the rise of magma to the surface in geological sciences.
At the Mid - Oceanic ridge, decompression melting occurs. As mantle ascends beneath the mid-ocean ridge, less and less rock lies above it, so large pressure changes occur, which leads to melting. The melt is less dense than the solid, and rises to the surface to form the oceanic crust.
At the subduction zone the magma that is formed is usually made up of silica rich lava. Thick silica rich magma does not release the gasses very easily so they build up inside the magma chamber. As the gasses collect in the chamber, the pressure rises. It is possible for the pressure to rise so much that the chamber cannot contain the magma and it erupts explosively.
find acceleration of block and tension in strings if m1 =8kg m2= 4kg and take g=10m/s²
[tex]\sf{m_1}[/tex] = 8kg
[tex]\sf{m_2}[/tex] = 4kg
g = 10m/s²
[tex]\large\bold{\underline{\underline{To \: Find:-}}}[/tex]→Acceleration of block
→Tension in strings
[tex]\large\bold{\underline{\underline{Solution:-}}}[/tex]Let, the two equation will be ,
[tex]\leadsto[/tex] 8g - T = 8a ..... Equation no (1)
[tex]\leadsto[/tex] T - 4g = 4a ..... Equation no (2)
Putting the value of equation no (1) and (2) we get,
[tex]\implies[/tex] 4g = 12a
[tex]\implies[/tex] 4 × 10 = 12a
[tex]\implies[/tex] 40 = 12a
[tex]\implies[/tex] a = [tex]\sf\dfrac{\cancel{40}}{\cancel{12}}[/tex]
[tex]\dashrightarrow[/tex] a = [tex]\dfrac{10}{3}[/tex]
Again, we have to putting the value of a in the equation no (2) we get,
[tex]\implies[/tex] T - 4g = 4 × [tex]\dfrac{10}{3}[/tex]
[tex]\implies[/tex] T - 4 × 10 = 4 × [tex]\dfrac{10}{3}[/tex]
[tex]\implies[/tex] T - 40 = [tex]\dfrac{40}{3}[/tex]
[tex]\implies[/tex] T = [tex]\dfrac{40}{3}[/tex] + 40
[tex]\implies[/tex] T = [tex]\dfrac{40 + 120}{3}[/tex]
[tex]\dashrightarrow[/tex] T = [tex]\dfrac{160}{3}[/tex] N
[tex]\therefore[/tex] Acceleration of block = [tex]\dfrac{10}{3}[/tex] m/s².
And, Tension in strings = [tex]\dfrac{160}{3}[/tex] N
400 N of load can be overcome by an effort of 50 N by using a lever. Calculate the mechanical advantage of the lever.
Answer:
load (l)=400N
Effort(E)=50N
mechanical advantage (MA)= load ÷Effort
(ma)=400÷50
(ma)=8
Explanation:
I copy pasted from the answer from the same question. Remember to first check if ur question is there
A satellite was in two separate crashes. In both crashes, the satellite had the same mass. Engineers want to know about the speed and direction of the satellite after the crashes. Why would the crash affect the motion of the satellite, and which crash caused a greater change in motion for the satellite?
Answer & Explanation:
Crashing into the asteroid would cause the satellite to slow down, stop, or reverse direction, because it is a force in the opposite direction to the satellite's motion. Whichever crash was a stronger force would cause it to change motion more. It takes a stronger force to change the velocity of a more massive object.
the person is not able to see the far lying object clearly. which type of lens will the doctor prescribe him give reason?
Answer:
correction of farsightedness uses a converging lenses that compensates for the under convergence by the eye. the converging lens produces an image farther from the eye than the object so that farsighted can see it clearly.
A fire is burning in a fireplace. Where is the radiation?
A. You touch warm bricks next to the fireplace
B. You can feel the heat from across the room
C. Heat is rising up from the chimney