Answer:
A) I_laser = 70.74 W/m²
B) I_bulb = 1.989 W/m²
C) it is not advisable to look at the laser beam directly.
Explanation:
We are given;
Power; P = 0.50 mW = 0.5 × 10^(-3) W
Diameter; d = 3 mm = 0.003 m
Radius; r = d/2 = 0.003/2 = 0.0015 m
A) Area of beam; A = πr²
A = 0.0015²π
Now, formula for average intensity is;
I = P/A
I = (0.5 × 10^(-3))/0.0015²π
I = 70.74 W/m²
B) We are told to find the intensity of a lightbulb producing 100-W.
Thus, P = 100 W
A light bulb is spherical in shape. Thus;
Area; A = 4πr²
We are told it's 2 m away.
Thus; r = 2 m
A = 4π(2)²
A = 16π
Thus, I = P/A = 100/16π
I = 1.989 W/m²
C) The intensity of the laser beam is far greater than that of the light bulb. Thus, it is not advisable to look at the laser beam directly.
Con lắc lò xo có độ cứng k = 100N/m được gắn vật có khối lượng m=0.1kg, kéo vật ra khỏi vị trí cân bằng 1 đoạn 5cm rồi buông tay cho vật dao động. Tính vmax vật có thể đạt được
Answer:
The maximum velocity is 1.58 m/s.
Explanation:
A spring pendulum with stiffness k = 100N/m is attached to an object of mass m = 0.1kg, pulls the object out of the equilibrium position by a distance of 5cm, and then lets go of the hand for the oscillating object. Calculate the achievable vmax.
Spring constant, K = 100 N/m
mass, m = 0.1 kg
Amplitude, A = 5 cm = 0.05 m
Let the angular frequency is w.
[tex]w = \sqrt{K}{m}\\\\w = \sqrt{100}{0.1}\\\\w = 31.6 rad/s[/tex]
The maximum velocity is
[tex]v_{max} = w A\\\\v_{max} = 31.6\times 0.05 = 1.58 m/s[/tex]
A 117 kg horizontal platform is a uniform disk of radius 1.61 m and can rotate about the vertical axis through its center. A 62.5 kg person stands on the platform at a distance of 1.05 m from the center, and a 28.3 kg dog sits on the platform near the person 1.43 m from the center. Find the moment of inertia of this system, consisting of the platform and its population, with respect to the axis.
Answer:
I_syst = 278.41477 kg.m²
Explanation:
Mass of platform; m1 = 117 kg
Radius; r = 1.61 m
Moment of inertia here is;
I1 = m1•r²/2
I1 = 117 × 1.61²/2
I1 = 151.63785 kg.m²
Mass of person; m2 = 62.5 kg
Distance of person from centre; r = 1.05 m
Moment of inertia here is;
I2 = m2•r²
I2 = 62.5 × 1.05²
I2 = 68.90625 kg.m²
Mass of dog; m3 = 28.3 kg
Distance of Dog from centre; r = 1.43 m
I3 = 28.3 × 1.43²
I3 = 57.87067 kg.m²
Thus,moment of inertia of the system;
I_syst = I1 + I2 + I3
I_syst = 151.63785 + 68.90625 + 57.87067
I_syst = 278.41477 kg.m²
state one similarity and one difference of sound of frequency 750Hz and ultrasound
Explanation:
Ultrasound refers to sound waves having frequencies greater than the frequency range limit. Ultrasound has the same physical qualities as "regular" (audible) music, except that individuals cannot hear it. Ultrasound devices use frequencies ranging from 20 kHz to a few gigahertz.
The frequencies of ultrasound utilised in clinical settings are generally between 2 and 12 MHz. Shorter wavelengths have a larger penetration depth into the body but less resolution; longer wavelengths have a greater depth of penetration but have a restricted depth of penetration.
The question is given in the picture below.... please help me and mention all the steps..
Answer:
a)water is turning into ice it is changing it's state from liquid to solid
b)B to C ice is melting and it is changing it's state from solid to liquid
C to D water is boiling and it is changing it's state from liquid to vapours(steam)
c) temperature
At A 0
At B 0
At C 100
At D 100
Explanation: The temperature will remain 0 degrees Celsius until all the ice becomes water and the temperature will remain 100 degrees Celsius until all the water changes into steam.
A ball is thrown vertically upward.It's velocity at the highest point is?
A. 10 ms^-1
B. Zero
C. 10 ms^-2
D. None of these
B
Explanation:
BECAUSE IT WAS GOING UPWORD THEN IT'S VELOCITY WAS DECREASING -10MS¹
Answer:
Explanation:
From physics, which is directly related to math (especially when it comes to parabolic motion!), we learn that at the very top of the parabola the object has to stop for a millisecond so it can turn around and fall back to earth. This translates to a velocity of 0 at its highest point. So B.
Q: Riri wants to bake a cake. She adds flour, sugar, egg, baking soda, and yeast into a bowl and mixed them together. After all the ingredients are mixed, she leaves the dough for 30 minutes and the dough starts to rise. Which changes Occurred in this process? Explain your reason.
Answer:
I don't know what you mean about which changes occurred in this process but if its why the dough starts rising then its caused by the carbon dioxide in baking soda and yeast which is a fungus
Answer:
When baking,flour is mixed with water,the other ingredients and yeast to form a paste called a dough.what happens is that the zymase enzyme from the yeast acts on the sugars to form carbon dioxide and alcohol.the carbon dioxide begins to form bubbles in the dough causing it to rise..
I hope this helps
The unit of work in terms of Newton and metre is _______
Answer:
Joule
Explanation:
the unit of work is Joule determined by the letter J.
Answer:
JouleExplanation:
Joule is defined as the work done by a force of one newton causing a displacement of one meter. Sometimes, newton-metre (N-m) is also used for measuring work.
A long distance runner running a 5km track is pacing himself by running 4.5km/h at 9km/h and the rest at 12.5km/h9
Complete Question:
A long distance runner running a 5.0km track is pacing himself by running 4.5km at 9.0km/hr and the rest at 12.5km/hr. What is the average speed?
Answer:
Average speed = 9.7333 km/h
Explanation:
Let the total distance be divided into A and B.Given the following data;
Total distance = 5 kmDistance A = 4.5 kmSpeed A = 9.5 km/hrSpeed B = 12.5 km/hrTo find the average speed;
First of all, we would determine the time taken to cover distance A in speed A by using the formula;
[tex] Time \ A = \frac {Distance \; A}{Speed \; A} [/tex]
Substituting the values into the formula, we have;
[tex] Time \ A = \frac {4.5}{9.5} [/tex]
Time A = 0.4737 hours
Total distance = distance A + distance B
5 = 4.5 + distance B
Distance B = 5 - 4.5
Distance B = 0.5 Km
Next, we would determine the time to cover distance B in speed B;
[tex] Time \ B = \frac {0.5}{12.5} [/tex]
Time A = 0.04 hours
Total time = time A + time B
Total time = 0.4737 + 0.04
Total time = 0.5137 hours
Now, we would solve for the average speed;
Mathematically, the average speed of an object is given by the formula;
[tex] Average \; speed = \frac {total \; distance}{total \; time} [/tex]
[tex] Average \; speed = \frac {5}{0.5137} [/tex]
Average speed = 9.7333 km/h
help me with this one
Answer:
may be d)45°
Explanation:
is noise energy a kind of energy or not
If the ring rolls (without slipping) all the way to point 2, what is the ring's energy at point 2 in terms of h2 and v2?
Answer:
Following are the response to the given question:
Explanation:
[tex]F_2=mgh_2+\frac{1}{2}mv_2^2+\frac{1}{2}mR^2(W)^2\\\\\therefore \\\\ \to WR=v_2\\\\E_2=Mgh_2+MV_2^2[/tex]
Two boys X and Y each have the same total weight
and are standing on soft ground.
Which boy is more likely to sink into the soft ground and
why?
boy more
likely to sink
pressure on soft
ground
А
Х
larger than Y
B
Х
smaller than Y
C
Y
larger than X
D
Y
smaller than X
Answer:
the child with the smallest area will be the one who sinks
Explanation:
The child who will sink to the ground is the one who exerts the greatest pressure on the ground, even though the force, which in this case is equal to the weight, is equal.
Pressure is defined by
P = F / A
in this case the strength of the children is their weight
F = W
P = W / A
therefore the pressure changes are in the area of contact with the ground, the child with the smallest area will be the one who sinks
if a person buys 10 kg apples in himalayan region and sells in terai region will he get profit or loss. why?
Answer:
he will be in profit
Explanation:
Himalayan region are high above the sea level so the gravity will be less there compared to the Terai region
Terai lies way below he Himalayan region so the pull of gravity will be more compared to Himalayan region
that's why he will be in profit but not loss
A flat, circular, copper loop of radius r is at rest in a uniform magnetic field of magnitude B that extends far beyond the edge of the loop. The plane of the loop is parallel to the page and the magnetic field is directed perpendicular to and out of the page, as indicated by the blue dots. If the magnitude of the magnetic field is decreased at a rate of 1 T/s, what is true about the induced current in the copper loop
Answer:
i =[tex]- \frac{r \ A'}{2 \ rho}[/tex] , i = 0.92 A
Explanation:
This exercise asks for the electromotive force, which can be calculated with Faraday's law
fem = [tex]- \frac{d \Phi_B }{dt}[/tex]
where the magnetic flux
Ф = B. A
bold letters indicate vectors. We can write this equation
Ф = B A cos θ
In this case the magnetic field is perpendicular to the page and the normal to the loop of the loop is also parallel to the page, therefore the angle is zero and the cosine is 1
the loop is
A = π r²
we substitute in the first equation
fem = - π r² [tex]\frac{dB}{dt}[/tex]
we substitute the values
fem = -π r² 1
fem = - π r²
to calculate the current let's use ohm's law
V = i R
R = ρ L / A'
where A 'is the area of the wire and L is the length of the loop
L = 2π r
V = i (ρ 2π r / A ')
I = [tex]\frac{V \ A'}{2\pi \ r \ rho}[/tex]
In this case
V = fem
I = fem / R
i =[tex]- \frac{r \ A'}{2 \ rho}[/tex]
In order to complete the calculation, you need the radius of the loop and / or the wire cutter.
if we assume that the loop has a radius of r = 1 cm = 0.01 m and an area of the wire A'= π 10⁻⁶ m² a radius of the wire 1 mm
i = - 10⁻² π 10⁻⁶ / ( 2 1.7 10-8)
i = 0.92 A
A comet of mass 2 × 10^8 kg is pulled toward the star. If the comet's initial velocity is very small, and the comet starts moving toward the star from 700,000,000 km away, how fast is it going right before it hits the surface of the star? (Assume that it does not lose any mass by melting as it approaches the star.)
Answer:
The speed of the comet at the surface of the star is approximately 1,208,694.7 m/s
Explanation:
Question parameter obtained online; The mass of the star, M = 5 × 10³¹ kg
Explanation;
The given mass of the comet, m = 2 × 10⁸ kg
The initial velocity of the comet, v → 0
The distance of the comet from the star, d = 700,000,000 km
The gravitational potential at d = G·M·m/d
The kinetic energy of the comet, K.E. = m·v²/2
The kinetic energy of the comet at d = m·(0)²/2 = 0
The gravitational potential at the surface of the star, R = G·M·m/R
The kinetic energy of the comet at the surface of the star, R = m·(v)²/2 = 0
Where;
M = The mass of the star = 5 × 10³¹ kg
[tex]M_{Sun}[/tex] = The mass of the Sun = 1.989 × 10³⁰ kg
M/[tex]M_{Sun}[/tex] = 5 × 10³¹/(1.989 × 10³⁰) ≈ 25
G = The universal gravitational constant = 6.67430 × 10⁻¹¹ N·m²/kg²
R = The radius of the star
Therefore, we have;
m·(0)²/2 - G·M·m/d = m·v²/2 - G·M·m/R
∴ v = √((G·M·m/R - G·M·m/d)×2/m) = √(2·G·M(1/R - 1/d))
Therefore; v = (2 × 6.67430 × 10⁻¹¹ × 5 × 10³¹ × (1/R - 1/700,000,000,000))
v = 81696389149.1×√(1/R - 1/700,000,000,000).
The speed of the comet at the surface of the star, v = 81696389149.1×√(1/R - 1/700,000,000,000)
The mass radius relationship is given as follows;
[tex]\dfrac{R}{R_{Sun}} = 1.30 \times \left(\dfrac{M}{M_{Sun}} \right)^{\dfrac{1}{2} }[/tex]
[tex]R = R_{Sun} \times 1.30 \times \left(\dfrac{M}{M_{Sun}} \right)^{\dfrac{1}{2} }[/tex]
The radius of the Sun = 696,340,000 M
∴ R ≈ 696,340,000 × 1.3 × √(25.14) = 4538865694.76
R = 4538865694.76 m
v = 81696389149.1×√(1/4538865694.76 - 1/700,000,000,000) ≈ 1208694.7 m/s
If there is 3.4 m3 of methane gas in a container with a pressure of 18.9 atm and the container expands until the methane has a pressure of 2.2 atm, what is the final volume of the methane? Temperature is constant at 305 K. A. 12.23 m3 B. 141.37 m3 C. 29.21 m3 OD. 2.53 m3
Answer:
C. 29.21 m³
Explanation:
Given the following data;
Initial volume, V1 = 3.4 m³Initial pressure, P1 = 18.9 atmFinal pressure, P2 = 2.2 atmTo find the final volume, we would use Boyle's law;
Boyles states that when the temperature of an ideal gas is kept constant, the pressure of the gas is inversely proportional to the volume occupied by the gas.
Mathematically, Boyles law is given by;
PV = K
[tex] P_{1}V_{1} = P_{2}V_{2} [/tex]
Making V2 the subject of formula, we have;
[tex] V_{2} = \frac {P_{1}V_{1}}{P_{2}} [/tex]
Substituting the values into the formula, we have;
[tex] V_{2} = \frac {18.9 * 3.4}{2.2} [/tex]
[tex] V_{2} = \frac {64.26}{2.2} [/tex]
Final volume, V2 = 29.21 m³
What is concave mirror?
Answer:
A concave mirror, or converging mirror, has a reflecting surface that is recessed inward (away from the incident light). Concave mirrors reflect light inward to one focal point. They are used to focus light.
(b) The power rating of an electrical appliance at 750watt,calculate consumed for using the appliance for 1 hour.
Answer:
750 w : time = 1hour
Explanation:
750x1hour
=750 watt-hours
Joule is equal to:
Awatt x metre
B.watt x second
C. Newton x Metre
D. Both b and c
Answer:
The answer is ( D) i. e both b and c.
The electrical resistance of an element in a platinum resistance thermometer at 100°c, 0°c and room temperature are 75.00Ω, 63.00Ω and 64.992Ω respectively. Use the data to calculate room temperature
Answer:
16.6 °C
Explanation:
From the question given above, the following data were obtained:
Temperature at upper fixed point (Tᵤ) = 100 °C
Resistance at upper fixed point (Rᵤ) = 75 Ω
Temperature at lower fixed point (Tₗ) = 0 °C
Resistance at lower fixed point (Rₗ) = 63.00Ω
Resistance at room temperature (R) = 64.992 Ω
Room temperature (T) =?
T – Tₗ / Tᵤ – Tₗ = R – Rₗ / Rᵤ – Rₗ
T – 0 / 100 – 0 = 64.992 – 63 / 75 – 63
T / 100 = 1.992 / 12
Cross multiply
T × 12 = 100 × 1.992
T × 12 = 199.2
Divide both side by 12
T = 199.2 / 12
T = 16.6 °C
Thus, the room temperature is 16.6 °C
A magnet falls through a loop of wire with the south pole entering first. After it has fallen all the way through the wire loop so that the north pole end is moving away from the loop, what is the direction of the induced current in the loop (as viewed from above, looking down on the magnet)
Answer:
The induced current direction as viewed is clockwise
Explanation:
Lenz's Law states that the induced e. m. f. causes current to be driven in the loop of wire in such a way as to generate magnetic field that are oppose the magnetic flux change which is the source of the induced current
Therefore, as the magnet approaches the coil with the south pole, the coil produces current equivalent to the upward movement of the south pole of a permanent magnet through it which according to Flemings Right Hand Rule is clockwise
Therefore;
The direction of the induced current in the loop (as viewed from above, looking down the magnet) is clockwise
what ia measurement in science?
= The process of comparing an unknown quantities with an standard known quantities is called measurement.
Yes it is the measurement in science
Why does the Earth exert a gravitational force on objects on its surface?
A. It has an atmosphere,
B. It has mass
C. It has a magnetic field.
D. It is so dense.
Answer:
B. It has mass
Explanation:
The Newtons Universal gravitacion law is : F = G.[tex]\frac{m1 m2}{d^{2} }[/tex] , where F is the force exerted , m1 and m2 are the earth's mass and the object's mass, d is the distance and G the gravitacional constant. Comparing to the options we can say that the Earth exerts a gravitational force on objects on its surface because of its mass.
HELP ASAP!!!
What size object (impactor) may create such a crater?
Answer:
I HOPE IT WILL HELP YOU.
:D
Which of the following is true of highly conductive elements?
Answer:
A
Explanation:
i think a is the answer because if you take an example of group 1 and 2 metals on the periodic table you will notice that they are highly reactive but they have a few electrons in their outer most shells.
I hope this helps
If you could travel 900 meters in 55 seconds, what is your speed?
(Answer in details=brainliest)
Answer:
The rate of change of distance is called speed it can also be defined as distance travelled per unit time,from these definition you can tell that the formula will be
speed=distance/time
in this question the distance is 900meters and the time is 55seconds therefore the speed will be:
s=900meters/55seconds
=16.36m/s
I hope this helps
For problems 2-3, a Ferrari accelerates from 0-60.0 miles per hour in 2.50 seconds.
2. What is its final speed, in m/s?
a 5.6 m/s
b. 13 m/s
c. 26.8 m/s
d. 1608 m/s
0-60.0 per near
2.50 seconds
3. What is its average acceleration?
a. 24.0 m/s
b. 10.7 m/s2
c. 38.6 m/s2
d. 13 m/s
Answer:
Explanation:
The first part of this question is simply asking us to convert the speed from miles per hour to meters per second:
[tex]60.0\frac{mi}{hr}*\frac{1hr}{3600sec}*\frac{1609.34m}{1mi}=26.8\frac{m}{s}[/tex] choice C.
The next part wants us to use the equation for acceleration and find the acceleration:
[tex]a=\frac{v-v_0}{t}[/tex] where v is final velocity, v0 is initial velocity, and t is time in seconds (which was one of the reasons we had to convert the initial velocity from 60.0 mph to m/s):
[tex]a=\frac{26.8-0}{2.5}[/tex] and
a = 10.7 m/s/s, choice B.
An object is thrown from the ground with an initial velocity of 30 m/s. What is the velocity at the point 25 m above the ground?
Answer:
It's a pretty simple suvat linear projectile motion question, using the following equation and plugging in your values it's a pretty trivial calculation.
V^2=U^2+2*a*x
V=0 (as it is at max height)
U=30ms^-1 (initial speed)
a=-g /-9.8ms^-2 (as it is moving against gravity)
x is the variable you want to calculate (height)
0=30^2+2*(-9.8)*x
x=-30^2/2*-9.8
x=45.92m
Answer:
35
Explanation:
dfddffffffffffffdddfr
Please help!! :)
For this circuit, what will be the voltage drop across R1?
A. 21.3 V
B. 14.2 V
C. 45.0 V
D. 9.47 V
Answer:
Option D. 9.47 V
Explanation:
We'll begin by calculating the equivalent resistance of the circuit. This can be obtained as follow:
Resistor 1 (R₁) = 20 Ω
Resistor 2 (R₂) = 30 Ω
Resistor 3 (R₃) = 45 Ω
Equivalent Resistance (R) =?
R = R₁ + R₂ + R₃ (series connections)
R = 20 + 30 + 45
R = 95 Ω
Next, we shall determine the current in the circuit. This can be obtained as follow:
Voltage (V) = 45 V
Equivalent Resistance (R) = 95 Ω
Current (I) =?
V = IR
45 = I × 95
Divide both side by 95
I = 45 / 95
I = 0.4737 A
Finally, we shall determine, the voltage across R₁. This can be obtained as follow:
NOTE: Since the resistors are in series connection, the same current will pass through them.
Current (I) = 0.4737 A
Resistor 1 (R₁) = 20 Ω
Voltage 1 (V₁) =?
V₁ = IR₁
V₁ = 0.4737 × 20
V₁ = 9.47 V
Therefore, the voltage across R₁ is 9.47 V.
Answer:
9.47
Explanation:
Just Took the Test
Vector A has magnitude of 8units and makes an angle of 45° with the positive x-axis. Vector B also has the same magnitude of 8units and directed along the negative x-axis. Find a. The magnitude and direction of A+B b. The magnitude and direction of A-B
Answer:
Explanation:
Because vectors have direction and x and y components you can't just add them and say that their length is 16 because A is 8 units and so is B. What you're actually finding is the magnitude and direction of the vector that results from this addition. The magnitude is the length of the resultant vector, which comes from the x and y components of A and B, and the direction is the angle between the resultant vector and the positive x axis. To add the vectors, then, we need to find the x and y components of each. We'll do the x components of A and B first so we can add them to get the x component of C. Since x values are directly related to cos, the formula to find the x components of vectors is
[tex]V_x=Vcos\theta[/tex] which is the magnitude of the vector (its length) and the angle. Finding the x components of A:
[tex]A_x=8.0cos45[/tex] so
[tex]A_x=5.7[/tex] and for B:
[tex]B_x=8.0cos180[/tex] since the negative x axis is the 180 degree axis and
[tex]B_x=-8.0[/tex] If we add them, we get
[tex]C_x=-2.3[/tex]
Now onto the y components. The formula for that is almost the same as the x components except use sin instead of cos:
[tex]A_y=8.0sin45[/tex] so
[tex]A_y=5.7[/tex] and
[tex]B_y=8.0sin180[/tex] so
[tex]B_y=0[/tex] If we add them, we get
[tex]C_y=5.7[/tex]
Now for the final magnitude:
[tex]C_{mag}=\sqrt{(-2.3)^2+(5.7)^2}[/tex] and
[tex]C_{mag}=6.1 units[/tex] and now onto the direction.
The x component of C is positive and the y component is negative, which means that the direction has us at an angle is quadrant 2; we add 180 to whatever the angle is. Finding the angle:
[tex]tan^{-1}(\frac{C_y}{C_x})=(\frac{5.7}{-2.3})[/tex] = -68 + 180 = 112 degrees
The resultant vector of A + B has a magnitude of 6.1 and a direction of 112°
Do the same thing for subtraction, except if you're subtracting B from A, the direction that B is pointing has to go the opposite way. That means that A doesn't change anything at all, but B is now pointing towards 0.
[tex]A_x=5.7[/tex] (doesn't change from above)
[tex]B_x=8.0cos0[/tex] and
[tex]B_x=8.0[/tex] so
[tex]C_x=13.7[/tex] and
[tex]A_y=5.7[/tex] (also doesn't change from above)
[tex]B_y=8.0sin0[/tex] so
[tex]B_y=0[/tex] and
[tex]C_y=5.7[/tex] and for the magnitude:
[tex]C_{mag}=\sqrt{(13.7)^2+(5.7)^2[/tex] so
[tex]C_{mag}=15units[/tex] and for the direction:
[tex]tan^{-1}(\frac{5.7}{13.7})=23[/tex] and since both x and y components of C are in Q1, we add nothing.
And you're done!!!
