Answer:
Distance = 6.667 kilometres
Explanation:
Given the following data;
Speed = 20 km/h
Departure time = 7:00
Arrival time = 7:20
Time taken = 20 minutes
To calculate the distance travelled from home to school;
First of all, we would have to convert the value of time in minutes to hours.
Conversion:
60 minutes = 1 hour
20 minutes = X hours
Cross-multiplying, we have;
X = 20/60 = 1/3 hours
Mathematically, the distance travelled by an object is calculated by using the formula;
Distance = speed * time
Distance = 20 * 1/3
Distance = 20/3 =
Distance = 6.667 kilometres
A stone is thrown vertically upwards with an initial velocity of 20m/s. Find the maximum height it reaches and the time taken by it to reach the height (g=10m/s).
Answer:
20m in 2 secs
Explanation:
t=2s
s=20m
hence the maximum height reached by stone is 20m in 2 s
Calculate the efficiency of the following appliances:
1. A radiator that converts 1000) of electrical energy into 900J
of heat energy and 100J of light energy
2. A torch that converts 100J of chemical energy into 35) of
light energy and 65J of heat energy
3. A car that converts 10,000J of chemical energy into 6000) of
kinetic energy and 4000J of heat energy.
4. An energy saver light converts 1,000J of electrical energy
into 7003 of light energy and 300J of heat energy.
5. A speaker converts 100J of electrical energy into 50J of
sound energy and 50J of heat and kinetic energy.
we
Answer:
1. The efficiency of the radiator is 90 %
2. The efficiency of the torch is 65 %
3. The efficiency of the car is 40 %
4. The efficiency of the energy saver is 70 %
5. The efficiency of the speaker is 50 %
Explanation:
Efficiency = (Useful energy out ÷ Total energy in) × 100 J
1. Useful energy = 900 J
The total energy in = 1000 J
The efficiency of the radiator = ((900 J)/(1,000 J)) × 100 % = 90 %
2. Useful energy = 65 J
The total energy in = 100 J
The efficiency of the torch = ((65 J)/(100 J)) × 100 % = 65 %
3. Useful energy = 4,000 J
The total energy in = 10,000 J
The efficiency of the car = ((4,000 J)/(10,000 J)) × 100 % = 40 %
4. Useful energy = 700 J
The total energy in = 1,000 J
The efficiency of the energy saver = ((700 J)/(1,000 J)) × 100 % = 70 %
5. Useful energy = 50 J
The total energy in = 100 J
The efficiency of the speaker = ((50 J)/(100 J)) × 100 % = 50 %
Multi-part question If a galaxy moving away from the Earth has a speed of 1000 km/s and emits 656 nm light characteristic of hydrogen (the most common element in the universe). What wavelength would we observe on the Earth
Answer:
658.2 nm
Explanation:
Since the galaxy is moving at relavitistic speed, we use the equation for relativistic Doppler shift of light.
So, the wavelength of light observed on the Earth is λ
λ = λ'([tex]\sqrt{\frac{ 1 + \frac{v}{c} }{1 - \frac{v}{c} } }[/tex])
where λ' = wavelength of light emitted by galaxy = 656 nm, v = speed of galaxy = 1000 km/s (positive since the galaxy is moving away from the Earth) and c = speed of light = 300000 km/s
So, substituting the values of the variables into the equation, we have
λ = λ'(√[{1 + (v/c)}/(1 - (v/c)]
λ = 656 nm(√[{1 + (1000 km/s/300000 km/s)}/(1 - (1000 km/s/300000 km/s)]
λ = 656 nm(√[{1 + 1/300}/(1 - 1/300]
λ = 656 nm(√[{(300 + 1)/300}/{(300 - 1)/300}]
λ = 656 nm(√[{(301)/300}/{(299)/300}]
λ = 656 nm(√[301/299])
λ = 656 nm(√1.0067)
λ = 656 nm × 1.0033
λ = 658.19 nm
λ ≅ 658.2 nm
So, the wavelength observed on Earth is 658.2 nm
Two children (each having a mass of 60 kg) are standing on the edge a merry-go-round (mass of 140 kg) as it spins with an angular velocity of 0.75 rad/s. The two children jump off the merry-go-round. What is the angular velocity of the merry-go-round after the children have jumped off
Answer:
The angular velocity after the children jump off is approximately 1.4 rad/s
Explanation:
The given parameters are;
The masses of each child, m₁, and m₂ = 60 kg
The mass of the merry-go-round, m₃ = 140 kg
The initial angular velocity, [tex]\omega_i[/tex] = 0.75 rad/s
The angular velocity after the children jump off = [tex]\omega_f[/tex]
According to the principle of conservation of angular momentum
The angular momentum = I × ω
The moment of inertia, I = m × R²
The total initial angular momentum = [tex]I_i \times \omega_i = m_i \times R^2 \times \omega_i[/tex]
The total angular momentum after the children jump off = [tex]I_f \times \omega_f = m_f \times R^2 \times \omega_f[/tex]
The initial mass, [tex]m_i[/tex] = m₁ + m₂ + m₃ = 60 kg + 60 kg + 140 kg = 260 kg
The final mass, [tex]m_f[/tex] = m₃ = 140 kg
According to the principle of conservation of linear momentum, we have;
[tex]I_i \times \omega_i[/tex] = [tex]I_f \times \omega_f[/tex]
Therefore;
260 kg × R² × 0.75 rad/s = 140 kg × R² × [tex]\omega_f[/tex]
∴ [tex]\omega _f[/tex] = (260 kg × R² × 0.75 rad/s)/(140 kg × R²) = 1.39285714 rad/s. ≈ 1.4 rad/s
The angular velocity after the children jump off, [tex]\omega _f[/tex] ≈ 1.4 rad/s.
Trong thí nghiệm về sự khúc xạ ánh sáng, một học sinh ghi lại trên tấm bìa ba đường truyền của ánh sáng như hình bên nhưng quên không ghi chiều truyền.
Tia khúc xạ là
Answer:
I R 2
Explanat
The velocity ratio of a pulley system is 4. What does it means
Answer:
Velocity ratio = distance travelled by effort / distance travelled by load. Which is equal to effort arm / load arm. When velocity ratio (VR) is 4, the effort arm is greater than load arm.
A) Give 3 examples of forces that are pulls and 3 examples that are pushes. b) For each example you give, state an approximate value for the size of the force.
Answer:
Explanation:
Force is defined as the push or pull which changes or tries to change the position, state of motion and the shape of the object.
(A) The examples of push are:
To push a chair on the floor, to push the car when it is stopped due to some problem, to push book on the table.
The examples of pull are :
To pull a chair towards you, to pull a string in a game of top, to pull the string in a gym.
(B) To push a chair or a book, the force required is small as compared to the to push a car.
To pull a chair or the string of top is less than the force to pull the string in gym.
What unit is used to measure the period of a wave?
A. Seconds
B. Meters
C. Hertz
D. Meters/second
Answer:
D. Meters/Seconds
Explanation:
The time period of a wave is measured in seconds.
A typical wave involves both time and distance. Consider a sound wave, which is basically a periodic modulation of the local air pressure. We "hear" the sound because our ears respond to the variations of pressure.
The most common metric of a sound wave is frequency. This is the rate at which the change in pressure occurs, and is measured in cycles per second, formally known as "hertz". The period is the inverse of frequency andl has the units of seconds per cycle, commonly stated simply as seconds.
A bucket filled woth water seems light while it sinks into water.Also show their relation using formula
Answer: This phenomenon happens due to upthrust exerted by water.
Explanation:
We know that,
Liquid Pressure is directly proportional to the height of the vertical column in the liquid.(P∝h)
When a bucket filled water is sunk into the water container, there occur difference in the pressure in top and bottom of the water container. Due to this, water exerts an upward force on the bucket filled with water. This is called Uprthrust.
Upthrust on the bucket makes the bucket filled with water lose some of it's weight and causes apparent loss in weight.
Hence, the bucket filled with water seems light while it sinks into water.
The coefficient of kinetic friction between an 100-kg desk and the wood floor is 0.4. What force (in Newtons) must be applied to move the desk at a constant speed? help now
Assuming the applied force is exerted parallel to the floor, by Newton's second law both the net vertical and net horizontal forces would be zero:
∑ F (horizontal) = p - f = 0 … … … because the desk is pushed at a constant speed
∑ F (vertical) = n - mg = 0 … … … because the desk doesn't move up or down
where p is the magnitude of the applied force, f is the mag. of kinetic friction, n is the mag. of the normal force due to contact between the floor and desk, and mg is the weight of the desk. We have
n = mg = (100 kg) g = 980 N
and the mag. of friction is proportional to n according to
f = 0.4 n = 392 N
Then the applied force p has magnitude
p = f = 392 N
Để có 100 lít nước ở 370C. Người ta pha nước đang sôi với nước ở 150C. Tính thể tích nước mỗi loại cần dùng.Biết khối lượng riêng của nước là 1000kg/m3
Answer:
nước sôi: 440/17 l
nước 15°C:1260/17 l
What is use of lemon Squeezer
Answer:
A lemon squeezer is a small kitchen utensil designed to extract juice from lemons or other citrus fruit such as oranges, grapefruit, or lime. It is designed to separate and crush the pulp of the fruit in a way that is easy to operate.
Answer:
A lemon squeezer is a small kitchen utensil designed to extract juice from lemons or other citrus fruit such as oranges, grapefruit, or lime. It is designed to separate and crush the pulp of the fruit in a way that is easy to operate.
Explanation:
stay safe
True or False. A compound is formed when two or more elements are combined to make a new substance with
its own properties
True
Fase
The Weight of an object is more at pole and less at equator of the earth. Give reason
The Weight of an object is more at pole and less at equator of the earth because the distance of the pole is less than the distance of the equator from the centre of the earth.
what weight is recorded by a scale when it is placed inside a lift which is in free fall? Enplain.
Answer:
Explanation:
There is no pressure of your feet on the scales, and no pressure of the floor on the scales, so the scales will read zero*. Hence, your weight, in a freely falling lift is zero
Hello! I am taking physics H on edge 2021 and if someone could give me the completed Electromagnetic Fields Plan an Investigation student guide/lab report I would be eternally grateful!!!
To create an electromagnetic field, a magnetic and electric field is involved.
An Electromagnetic field planElectromagnetic field consists of both electric and magnetic fields which are produced by human activities through the use of electricity.
With the above definition of electromagnetic field, it's production will involve:
Magnetic field: These fields are created by the magnets.Electric field: These fields are created by electric charges.These fields oscillate in perpendicular planes with respect to each other, and are in phase.
Therefore, to create an electromagnetic field, a magnetic and electric field is involved.
Learn more about electromagnetic field here:
https://brainly.com/question/1594186
Answer:
I need this as well
Explanation:
If the poster got the project, please let me know. I'm struggling on this unit and if you don't want to give out the project, help is appreciated too! thanks
difference Between Newton's first and third law
Explanation:
In the first law, an object will not change its motion unless a force acts on it. In the second law, the force on an object is equal to its mass times its acceleration. In the third law, when two objects interact, they apply forces to each other of equal magnitude and opposite direction.6 days ago
Newton first law state that anything in motion or on rest will continue to do so until an external force is applied on it
Newton 3rd law stare that every action have equal and opposite reaction
An oscillator completes 240 cycles in 5.2 minutes.
Calculate its period (in seconds) and frequency (in Hz).
Answer:
I. Period = 1.3 seconds
II. Frequency = 0.769 Hertz
Explanation:
Given the following data;
Number of oscillation = 240 cycles
Time = 5.2 minutes.
Conversion:
1 minute = 60 seconds
5.2 minutes = X seconds
X = 60 * 5.2
X = 312 seconds
To find the following;
I. Period
Mathematically, the number of oscillation of a pendulum is given by the formula;
[tex] Number \; of \; oscillation = \frac {Time}{Period} [/tex]
Making period the subject of formula, we have;
[tex] Period = \frac {Time}{Number \; of \; oscillation} [/tex]
Substituting into the formula, we have;
[tex] Period = \frac {312}{240} [/tex]
Period = 1.3 seconds
II. Frequency
[tex] Frequency = \frac {1}{Period} [/tex]
Substituting the values into the formula, we have;
[tex] Frequency = \frac {1}{1.3} [/tex]
Frequency = 0.769 Hertz
20 The metal surface of a kettle is hot. What happens to the cool air outside the kettle when it comes into contact with the hot kettle?
A The density of the air decreases and the air falls.
B The density of the air decreases and the air rises.
C The density of the air increases and the air falls.
D The density of the air increases and the air rises.
D. The density of the sir increases and the air rises.
When coming in contact with the kettle, it becomes hot, it expands and rises up, due to lesser density as compared to the surrounding air.
4. An aluminium bar weighs 17 kg in air. How much force is required
to lift the bar while it is immersed in gasoline? The density
of aluminium is 170 kg/m' and that of gasoline is 42 kg/m
Explanation:
1ml = 2.7g
Xml = 1.5g
Divide 1.5 by 2.7 to find X.
Obviously, since 1.5 is less than 2.7, you know the answer will be less than 1.
(it’s .5555555555)
solve two questions under inclined plane using Newton 2nd law
Explanation:
If the mass of the inclined plane is large enough, could N ever be equal to mgcosθ. Reasons?
So far I've come up with: mgcosθ−N=ma meaning if N were to equal mgcosθ, ma=0. Since the surfaces are frictionless and since N is acting on the inclined plane too(it'll have a horizontal component), this isn't possible. Am I right? Where am I going wrong?
kí hiệu Δs trong vật lí là gì?
Answer:
which language is this
Explanation:
J.J. Thomson theorized that, if an atom had all of its negatively charged
electrons removed, the remaining material would be
A. neutral
B. negatively charged
C. positively charged
D. magnetic
Answer:
C. Positively charged
Explanation:
The plum pudding model of the atom proposes by J. J. Thomson consisted of electrons which lay embedded as the raisins within a dough or soup that was positively charged. The electron was discovered by J. J. Thomson in 1897 through cathode ray tube experiments.
Based on the plum pudding model, if all the negatively charge electrons contained in an atom are removed, the material remaining will be the positively charged soup
how do u calculate the kinetic energy of a ball of mass 0.25kg being kicked vertically upwards with a speed of 5m/s
Answer:
3.125J
Explanation:
K.E.= 1/2(mass)(velocity)^2
K.E.=1/2(0.25)(5)^2=3.125
sort out electric current as fundamental or derived unit.
Answer:
electric current is derived unit.
Explanation:
According to the definition of electric current, it appears to be a derived quantity. Charge on the other hand seems more fundamental than electric current.
please help me with this I really need help
Answer:
Ask with your Science teacher
Explanation:
i do not know the ans
Please help
25 Points
What Mathematical leads to the formulas for the magnitudes of displacement, velocity, and acceleration?
Answer:
displacement=specific distance
*Velocity=∆displacement/time
*acceleration=∆velocity/time
state and prove Newton's second law of motion
Answer:
HOPE IT HELP YOU A LOT :)
I prove it also .
Answer:
Newtons Second law of motion states that"The rate of change of momentum is directly proportional to the force applied"
define electrical resistance in a metal conductor
Answer:
Resistance is defined as the property of a conductor to resist the flow of charges through it. The resistance of conductor is numerically given as the ratio of potential difference across its length to the current flowing through it.
Explanation:
You are pushing a cart at the grocery store. The cart is speeding up. a) When your friend drops a 50 pound bag of dog food into the cart you are pushing, what would happen to the acceleration of the cart? Explain your answer using Newton's Second Law.
Answer:
The acceleration will decrease/reduce
Explanation:
Newton in his second law of motion states that the acceleration of an object is dependent on the force and mass applied on the object. Using the equation as follows:
F = m × a
Where;
F = force (N)
m = mass (kg)
a = acceleration (m/s²)
Acceleration (a) is directly proportional to the force (F) applied but inversely proportional to the mass (m).
According to this question, a friend drops 50 pounds of dog food into a cart being pushed with speed. This means that the mass/weight of the cart was increased. Since the acceleration is inversely proportional to the mass of an object, this means that the acceleration of the cart will DECREASE/REDUCE as the mass increases.
