Answer:
D. 12.5 min
Explanation:
Speed = distance ÷ time.
time = distance ÷ speed.
18km × 1000m = 18000m (as speed is in m/s).
time = 18000m ÷ 24.0m/s
t = 750s.
750s ÷ 60
= 12.5mins is your answer.
hope this helps. :)
Help me pls???!!
In the circuit shown, the
battery voltage, V = 12V and the load resistance, R = 252.
The ammeter reading is____
A.
The Voltmeter reading is_____
V.
Answer:
A. I = V / R = 12 / 252 = .048 amps
V = I * R = .048 * 252 = 12 V
V is also the reading the voltage across the battery (12 Volts)
How do particle motion and temperature change as a material absorbs heat?
I really need the answer
Answer:
The first answer is correct. All of the other options include sound, which travels by material force, and can not be transmitted in a vacuum. Infra-red, radio, and microwaves are all different frequencies of light, and can thus travel through a vacuum.
How much heat is required to boil 500 grams of water at 100 degrees C if the Hy is 813,700 J/g? Be sure to put the correct units at the end of
Answer:
406850000 J
Explanation:
From the question
Q = cm...................... Equation 1
Where Q = Amount of heat, c = latent heat of water, m = mass of water
Given: c = 813700 J/g, m = 500 grams
Substitute these values into equation 1
Q = 500×813700
Q = 406850000 J
Hence the amount of heat requires to boil water at 100°C = 406850000 J
Two polarizing sheets have their transmission axes crossed so that no light is transmitted. A third sheet is inserted so that its transmission axis makes an angle with the transmission axis of the first sheet. (a) Derive an expression for the intensity of the transmitted light as a function of (b) Show that the intensity transmitted through all three sheets is maximum when\
Answer:
a) I= I₀ (cos²θ - cos⁴θ) b) 75.5º
Explanation:
a) For this exercise we must use Malus's law
I = I₀ cos² θ
where tea is the angle between the two polarizers.
We apply this expression to our case
* Polarizer 1 suppose that it is vertical and polarizer 2 (intermediate) is at an angle θ with respect to the vertical
I₁ = I₀ cos² θ
* We analyze for the polarity 2 and the last polarizer 3 which indicate that it must be at 90º from the first one, therefore it must be horizontal.
The angle of polarizers 2 and 3 is θ' measured from the horizontal, if we measure with respect to the vertical
θ₂ = 90- θ’ = θ
fiate that in the exercise we must take a reference system and measure everything with respect to this system.
I = I₁ cos² θ'
we substitute
I = (I₀ cos² tea) cos² (θ - 90)
cos (θ -90) = cos θ cos 90 + sin θ sin 90 = sin θ
I = Io cos² θ sin² θ
1= cos²θ+ sin²θ
sin²θ = 1 - cos²θ
I= I₀ (cos²θ - cos⁴θ)
b) to find when the intensity is maximum,
we can use that we have an extreme point when the drift is zero
[tex]\frac{dI}{d \theta}[/tex] = 0
\frac{dI}{d \theta}= Io (2 cos θ - 4 cos³θ) = 0
whereby
cos θ - 2 cos³ θ = 0
cos θ ( 1 - 2 cos² θ) = 0
The zeros of this function are in
θ = 90º
1-2cos²θ =0 cos θ = 0.25 θ = 75.5º
Let's analyze this two results for the angle of 90º the intnesidd is zero with respect to the first polarizer, so it is not an acceptable solution.
Consequently, the angle that allows the maximum intensity to pass is 75.5º
The diagram below shows waves A and B in the same medium
am
Compared to wave A, wave B has:
a) twice the amplitude and twice the wavelength
Ob) twice the amplitude and half the wavelength
O c) half the amplitude and the same wavelength
the same amplitude and half the wavelength
I need help with both questions please
Answer:
2) twice the amplitude and half the wavelength
Explanation:
The diagram below represent that the waves A and B in the same medium should be option b where the amplitude is to be twice and the wavelength should be half.
What is amplitude?Amplitude in terms of physics that represent the maximum displacement or the distance that should be moved via the point with respect to the vibrating body or the wave that should be determined from the equilibrium position.
Also, it should be equivalent to the one half the vibration path length.
Therefore, the option b is correct.
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1. A 455 g mass, hanging at rest on a spring, stretches the spring 22.4 cm beyond its relaxed
position. What is the spring constant of that spring?
Answer:
19.9 N/m
Explanation:
From the question,
Applying Hook's law
F = Ke.................. Equation 1
Where F = Force on the spring, k = spring constant, e = extension
But the force on the spring is the weight of the mass
Therefore,
mg = ke.................. Equation 2
Where m = mass. g = acceleration due to gravity
make e the subject of the equation
e = mg/e................ Equation 3
Given: m = 455 g = 0.455 kg, e = 22.4 cm = 0.224 m,
Constant: g = 9.8 m/s²
Substitute these values into equation 3
e = (0.455×9.8)/0.224
e = 19.9 N/m
The spring constant of the given spring is 20 N/m.
The given parameters:
Mass attached, m = 455 g = 0.455 kgExtension of the spring, x = 22.4 cm = 0.224 mThe spring constant is calculated by applying Hooke's law as follows;
[tex]F = kx\\\\mg = kx\\\\k = \frac{mg}{x} \\\\k = \frac{0.455 \times 9.8}{0.224} \\\\k = 20 \ N/m[/tex]
Thus, the spring constant of the spring is 20 N/m.
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2. Oscar walked to the milktea house for a snacks. He walk 2 kilometers
east, 2 kilometers south, and 2 kilometers west. What distance did he
cover? What was the displacement?
The distance Oscar covered was 6km while the displacement was 2km.
What is Displacement?Displacement is defined as the vector whose length is the shortest
distance from the initial to the final position of a point M.
Distance = Total length of space between points
= 2km+ 2km+ 2km = 6km.
Displacement = 2km.
This is because it is the shortest distance from the positions in this
scenario.
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1 ) when a ball is projected upwords its time of rising is ...............the time of falling .
a) greater than b) smaller than c) equal to d ) double
2 ) when an object falls freely under the effect of gravity , the distance moved is
a ) directly proportional to time
b ) inversely proportional to time
c ) directly proportional to square of time
d ) inversely proportional to square of time.
Answer:
correct answer is C
Explanation:
In this exercise, you are asked to complete the sentences so that the sentence makes sense.
1) in projectile launching, the only force that acts is gravity in the vertical direction, so the time of going up is EQUAL to the time of going down
correct answer C
2) when a body falls freely, the acceleration is the ratio of gravity, therefore if it starts from rest, its height is
y = v₀ t - ½ gt²
v₀ = 0
y = -1/2 g t²
so the position is not proportional to the square of the time
correct answer is C
Tarzan, whose mass is 103 kg, is hanging at rest from a tree limb. Then he lets go and falls to the ground. Just before he lets go, his center of mass is at a height 2.4 m above the ground and the bottom of his dangling feet are at a height 1.5 above the ground. When he first hits the ground he has dropped a distance 1.5, so his center of mass is (2.4 - 1.5) above the ground. Then his knees bend and he ends up at rest in a crouched position with his center of mass a height 0.3 above the ground.
Required:
Consider the real system. What is the net change in internal energy for Tarzan from just before his feet touch to the ground to when he is in the crouched position?
Answer:
v₀ = 60.38 mi / h
With this stopping distance, the starting speed should have been 60.38 mi/h, which is much higher than the maximum speed allowed.
Explanation:
For this exercise let's start by using Newton's second law
Y axis
N-W = 0
N = W
X axis
fr = m a
the expression for the friction force is
fr = μ N
we substitute
μ mg = m a
μ g = a
calculate us
a = 0.620 9.8
a = 6.076 m / s²
now we can use the kinematics relations
v² = v₀² - 2 a x
suppose v = 0
v₀ = [tex]\sqrt{2ax}[/tex]Ra 2ax
let's calculate
v₀ = [tex]\sqrt{2 \ 6076 \ 60}[/tex]
v₀ = 27.00 m / s
let's slow down to the english system
v₀ = 27.0 m / s (3.28 ft / 1m) (1 mile / 5280 ft) (3600s / 1h)
v₀ = 60.38 mi / h
With this stopping distance, the starting speed should have been 60.38 mi/h, which is much higher than the maximum speed allowed.
Two resistors 5 ohm's each can be combined to give an equivalent resistance of
Answer: 10 Ω or 2.5 Ω
Explanation:
In series resistance R = 5 Ω + 5 Ω =10 Ω. If resistors are parallel, resistance is
1/R = 1/5Ω+ 1/5Ω and R = 2,5 Ω
What is one benefit to measuring your body’s flexibility?
A.
meeting the national requirement for flexibility
B.
determining your muscular strength
C.
tracking your flexibility improvements over time
D.
increasing the length of your life
Answer:
C
Explanation:
if you measure your body's flexibility then you can keep track of how flexible you have gotten over time
Prove the correctness of this equation s=vt + 1/2at
Answer:
The formula is dimensionally correct.
Explanation:
Given
[tex]s = ut + \frac{1}{2}at^2[/tex]
Required
Prove its correctness
Write out the dimension of each:
[tex]s = M^0LT^0[/tex] --- displacement
[tex]ut = M^0LT^{-1} * T[/tex] --- velocity * time
[tex]\frac{1}{2}at^2 = M^0LT^{-2} * T^2[/tex] --- acceleration * square of time
The expression becomes:
[tex]s = ut + \frac{1}{2}at^2[/tex]
[tex]M^0LT^0 = M^0LT^{-1} * T + M^0LT^{-2} * T^2[/tex]
Apply law of indices
[tex]M^0LT^0 = M^0LT^{-1+1} + M^0LT^{-2+2}[/tex]
[tex]M^0LT^0 = M^0LT^{0} + M^0LT^{0}[/tex]
[tex]M^0LT^0 = M^0LT^{0}[/tex]
Both sides of the equation are equal
A small rubber wheel is used to drive a large pottery wheel. The two wheels are mounted so that their circular edges touch. The smalldrive-wheel has a radius of 2.20 cm and accelerates at the rate of 8.00 rad/s2, and it is in contact with the pottery wheel (radius 28.0 cm). Both wheels move without slipping.The rubber drive wheel rotates in the clockwise sense.
Required:
a. Find the angular acceleration (both magnitude and direction) of the large pottery wheel.
b. Calculate the tune it takes the pottery wheel to reach its required speed of 60 rpm. if both wheels start from rest.
Answer:
[tex]0.629\ \text{rad/s}^2[/tex] counterclockwise
[tex]9.98\ \text{s}[/tex]
Explanation:
[tex]r_1[/tex] = Small drive wheel radius = 2.2 cm
[tex]\alpha_1[/tex] = Angular acceleration of the small drive wheel = [tex]8\ \text{rad/s}^2[/tex]
[tex]r_2[/tex] = Radius of pottery wheel = 28 cm
[tex]\alpha_2[/tex] = Angular acceleration of pottery wheel
As the linear acceleration of the system is conserved we have
[tex]r_1\alpha_1=r_2\alpha_2\\\Rightarrow \alpha_2=\dfrac{r_1\alpha_1}{r_2}\\\Rightarrow \alpha_2=\dfrac{2.2\times 8}{28}\\\Rightarrow \alpha_2=0.629\ \text{rad/s}^2[/tex]
The angular acceleration of the pottery wheel is [tex]0.629\ \text{rad/s}^2[/tex].
The rubber drive wheel is rotating in clockwise direction so the pottery wheel will rotate counterclockwise.
[tex]\omega_i[/tex] = Initial angular velocity = 0
[tex]\omega_f[/tex] = Final angular velocity = [tex]60\ \text{rpm}\times \dfrac{2\pi}{60}=6.28\ \text{rad/s}[/tex]
t = Time taken
From the kinematic equations of linear motion we have
[tex]\omega_f=\omega_i+\alpha_2t\\\Rightarrow t=\dfrac{\omega_f-\omega_i}{\alpha_2}\\\Rightarrow t=\dfrac{6.28-0}{0.629}\\\Rightarrow t=9.98\ \text{s}[/tex]
The time it takes the pottery wheel to reach the required speed is [tex]9.98\ \text{s}[/tex]
What is R2 in the circuit?
WILL GIVE BRAINLIEST !!!!
Answer:
1. Rₑq = 4 Ω
2. R₂ = 6 Ω
3. Vₜ = 12 V, V₁ = 12 V, V₂ = 12 V
4. Iₜ = 3 A, I₁ = 1 A, I₂ = 2 A
Explanation:
1. Determination of the equivalent resistance
Voltage (V) = 12 V
Current (I) = 3 A
Resistance (Rₑq) =?
V= IRₑq
12 = 3 × Rₑq
Divide both side by 3
Rₑq = 12 / 3
Rₑq = 4 Ω
Thus, the equivalent resistance (Rₑq) = 4 Ω
2. Determination of R₂.
Equivalent resistance (Rₑq) = 4 Ω
Resistance 1 (R₁) = 12 Ω
Resistance 2 (R₂)
Since the resistor are in parallel arrangement, the value of R₂ can be obtained as follow:
Rₑq = R₁ × R₂ / R₁ + R₂
4 = 12 × R₂ / 12 + R₂
Cross multiply
4(12 + R₂) = 12R₂
48 + 4R₂ = 12R₂
Collect like terms
48 = 12R₂ – 4R₂
48 = 8R₂
Divide both side by 8
R₂ = 48 / 8
R₂ = 6 Ω
3. Determination of the total voltage (Vₜ), V₁ and V₂.
From the question given above, the total voltage is 12 V
Since the resistors are arranged in parallel connection, the same voltage will go through them.
Thus,
Vₜ = V₁ = V₂ = 12 V
4. Determination of the total current (Iₜ), I₁ and I₂
From the question given above, the total current (Iₜ) is 3 A
Next, we shall determine I₁. Since the resistors are arranged in parallel connection, different current will pass through each resistor respective.
Vₜ = V₁ = 12 V
R₁ = 12 Ω
I₁ =?
V₁ = I₁R₁
12 = I₁ ×12
Divide both side by 12
I₁ = 12 / 12
I₁ = 1 A
Next, we shall determine I₂. This can be obtained as follow:
Iₜ = 3 A
I₁ = 1 A
I₂ =?
Iₜ = I₁ + I₂
3 = 1 + I₂
Collect like terms
I₂ = 3 – 1
I₂ = 2 A
A 0.90-m steel bar is held with its length parallel to the east-west direction and dropped from a bridge. After it has fallen 32 m, the emf across its length is 9.2 x 10-4 V. Assuming the horizontal component of the earth's magnetic field points directly north, what is the magnitude of the horizontal component of the earth's magnetic field
Explanation:
From Faraday's law,
[tex]e m f &=-\frac{d \phi}{d t} \\ &=-\frac{d}{d t}(B A \cos \theta) \\ &=-\frac{d}{d t}(B l h \cos \theta) \\ &=-B l \cos \theta \frac{d h}{d t} \\ &=-B l v \cos 0^{\circ} \\ &=-B l v[/tex]
Here, B is the magnetic field, l is the length of the rod, and v is the velocity of the rod.
[tex]e m f &=-B l(\sqrt{2 g h}) \\ 9.2 \times 10^{-4} \mathrm{~V} &=-B(0.90 \mathrm{~m})\left(\sqrt{2\left(9.8 \mathrm{~m} / \mathrm{s}^{2}\right)(32 \mathrm{~m})}\right) \\ B &=\frac{9.2 \times 10^{-4} \mathrm{~V}}{(0.90 \mathrm{~m})\left(\sqrt{2\left(9.8 \mathrm{~m} / \mathrm{s}^{2}\right)(32 \mathrm{~m})}\right)} \\ &=0.408 \times 10^{-4} \mathrm{~T}[/tex]
Question 12 of 34 Which of the following means that an object is slowing down? /13 ယာ O A. Its velocity is decreasing. B. Its acceleration is increasing. O C. Its acceleration is decreasing. O D. Its velocity is increasing.
Answer:
A. Its velocity is decreasing
Explanation:
1. The nearest distance of distinct vision of
a hypermetropial person is 60 cm. If this
distance is reduced by 20 cm by using
spectacles. What is the nature and focal
length of the lens?
a. +30 cm b. +35 cm
-30 cm
d. -40 cm
c.
Answer:
The focal length of the lens is +30 and it is a convex lens.
Explanation:
Given that,
The nearest distance of distinct vision of a hypermetropial person is 60 cm, v = -60 cm
The distance is reduced by 20 cm, u = -20 cm
We need to find the nature and focal length of the lens.
Let f be the focal length of the lens. Using lens formula,
[tex]\dfrac{1}{v}-\dfrac{1}{u}=\dfrac{1}{f}\\\\\dfrac{1}{f}=\dfrac{1}{(-60)}-\dfrac{1}{(-20)}\\\\f=+30\ cm[/tex]
So, the focal length of the lens is +30 and it is a convex lens.
a pool and stops at the
Which best describes his
motion?
A. Linear
B. Projectile
C. Vibrational
In Linear motion the swimmer swims
Answer: A
Explanation: Linear motion.
What is earth's magnetic field made of
Answer:
if you have a rotating electric current it will create a magnetic field on earth flowing of liquid metal in the outer core of the planets General Health recurrence the rotation of earth on its Axis causes this electric current to form a magnetic field which extends around the planet.
Explanation:. please give me brainlest
a car is travelling at 18m/s accelerates ti 30m/s in 3seconds. what's the acceleration of the car
[tex] \Large {\underline { \sf {Required \; Solution :}}}[/tex]
We have ―
Initial velocity, u = 18 m/sFinal velocity, v = 30 m/sTime taken, t = 3 secondsWe've been asked to calculate acceleration.
[tex]\qquad \implies\boxed{\red{\sf{ a = \dfrac{v-u}{t} }}}\\[/tex]
a denotes accelerationv denotes final velocityu denotes initial velocityt denotes time[tex] \twoheadrightarrow \quad \sf {a = \dfrac{30-18}{3} \; ms^{-2} } \\ [/tex]
[tex] \twoheadrightarrow \quad \sf {a =\cancel{ \dfrac{12}{3} \; ms^{-2} }} \\ [/tex]
[tex]\twoheadrightarrow \quad \boxed{\red{\sf{ a = 4 \; ms^{-2} }}}\\[/tex]
Therefore, acceleration of the car is 4 m/s².
The power is inversely proportional with time
Answer:
True
Explanation:
Given that Power whose unit is Watt equates to one joule of work per second. It implies that Power is directly proportional to the work done and inversely proportional to the time to do the work.
Therefore, in this case, the right answer to the question is that it is TRUE that the power is inversely proportional with time
A closed, rigid container holding 0.2 moles of a monatomic ideal gas is placed over a Bunsen burner and heated slowly, starting at a temperature of 300 K. The initial pressure of the ideal gas is atmospheric pressure, and the final pressure is four times the initial pressure.
Determine the following:
a. the change in the internal energy of the gas.
b. the work done by the gas.
c. the heat flow into or out of the gas.
Answer:
a) 2250 J
b) 0 J
c) 2250 J
Explanation:
a) Since, the process is isochoric
the change in internal energy
[tex]\Delta U = n C_v(T_f-T_i)[/tex]
Here, n = 0.2 moles
Cv = 12.5 J/mole.K
We have to find T_f so we can use gas equation as
[tex]\frac{P_1V_1}{P_2V_2} =\frac{T_i}{T_f}\\Since, V_1=V_2 [isochoric/process]\\\Rightarrow \frac{P_{atm}}{4P_{atm}} = \frac{300}{T_f} \\\Rightarrow T_f = 1200 K[/tex]
So, [tex]\Delta U= 0.2\times12.5(1200-300)\\=2250 J[/tex]
b) Since, the process is isochoric no work shall be done.
c) By first law of thermodynamics we have
[tex]\Delta U = Q-W\\Since, W = 0\\\Delta U = Q\\Therefore, Q = 2250 J[/tex]
Since, Q is positive 2250 J of heat will flow into the system.
A rocket sled accelerates from rest for a distance of 645 m at 16.0 m/s2. A parachute is then used to slow it down to a stop. If the parachute gives the sled an acceleration of -18.2 m/s2 and there is 500.0 m of sled track remaining after the shoot opens, will the sled stop before running off the track? Show why or why not?
Answer:
the stopping distance is greater than the free length of the track, the vehicle leaves the track before it can brake
Explanation:
This problem can be solved using the kinematics relations, let's start by finding the final velocity of the acceleration period
v² = v₀² + 2 a₁ x
indicate that the initial velocity is zero
v² = 2 a₁ x
let's calculate
v = [tex]\sqrt {2 \ 15.0 \ 645}[/tex]
v = 143.666 m / s
now for the second interval let's find the distance it takes to stop
v₂² = v² - 2 a₂ x₂
in this part the final velocity is zero (v₂ = 0)
0 = v² - 2 a₂ x₂
x₂ = v² / 2a₂
let's calculate
x₂ = [tex]\frac{ 143.666^2 }{2 \ 18.2}[/tex]
x₂ = 573 m
as the stopping distance is greater than the free length of the track, the vehicle leaves the track before it can brake
what is the power output needed from a motor to lift in the absence of friction a mass of 1.5 ×10⁴ kg 25 m in 6.0 s at constant speed
Answer:
the power output needed is 61.25 × 10⁴
Explanation:
The computation of the power output needed is shown below;
Given that
m = 1.5 ×10⁴ kg
v = 25m ÷ 6.0 s
And g = 9.8 m/sec^2
Now based on the above information
p = f × v
= mg × v
= 1.5 ×10⁴ × 9.8 × 25 ÷ 6
= 61.25 × 10⁴
Hence, the power output needed is 61.25 × 10⁴
In one cycle of any heat engine
A. the net work done is larger than the heat exhausted.
B. more heat flows from the engine than enters the engine.
C. The internal energy of the engine does not change.
D. the net heat flow is zero.
Answer:
D. the net heat flow is zero
Explanation:
In one cycle of any heat engine, three things happen:
Heat is added; this causes high temperature in the engine ([tex]Q_H[/tex])Some of the energy from that input heat is used to perform work (W). The rest of the heat is removed at a relatively cold temperature ([tex]Q_C[/tex]).[tex]Q_H = W + Q_C[/tex]
Conclusively, the net heat flow is zero
explain the working and performance of a centrifugal clutch with a sketch
a centrifugal clutch works, as the name suggests, through centrifugal force. ... The rotation of the hub forces the shoes or flyweights outwards until they come into contact with the clutch drum, the friction material transmits the torque from the flyweights to the drum. The drive is then connected
WHEN AN OBJECT IS DROPPED WHAT HAPPENDS TO THE POTENTIAL AND KENETIC ENERGY AS IT FALLS?
Answer:
The sum of an object's potential and kinetic energies is called the object's mechanical energy. As an object falls its potential energy decreases, while its kinetic energy increases. The decrease in potential energy is exactly equal to the increase in kinetic energy.
Explanation:
Answer:
the potential decrease and kinetic increase
Explanation:
because it goes from a state of rest to a state of movement
what is Newton's second law
Newton's Second Law of Motion states "The rate of change of momentum of a body is directly proportional to the applied unbalanced force in the direction of force".
What does the force of attraction called gravity act on?
A. every mass
B. no masses
C. nearby masses
D. select masses
Answer:
Every mass
Explanation:
Because Force of gravity always act toward the center of the earth , so when an object is thrown up ,the force of gravity will act in opposite direction of motion ,that's toward the center of earth. The force is towards the center of the Earth (more or less). which gives it time get touch every mass.
The gravitational force of attraction exists between every objects in the universe that are having mass. So, the correct option is A.
What is meant by the force of gravity ?Force of gravity is defined as the force of attraction experienced by bodies due to the gravitational field of earth.
Here,
The gravitational force is the attractive force experienced by any body that have mass. Gravity is an attractive force such that every bodies that are having mass in the earth are being attracted towards the centre of earth.
The equation of gravitational force is given by,
F = GMm/r²
where G is the gravitational constant of earth, M is the mass of earth and m is the mass of the body which is being attracted towards earth's centre, and r is the distance between earth and the body.
From the equation, it is shown that gravitational force is proportional to the masses. More the mass of the objects, more will be the gravitational force of attraction existing between them.
Hence,
The gravitational force of attraction exists between every objects in the universe that are having mass.
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