A person carries a plank of wood 1.9 m long with one hand pushing down on it at one end with a force F1 and the other hand holding it up at 49 cm from the end of the plank with force F2. If the plank has a mass of 14 kg and its center of gravity is at the middle of the plank, what are the magnitudes of the forces F1 and F2? (The distance of 49 cm is measured from the location of F1.)
Answers
Solution :
Given :
mass of the plank, m = 14 kg
length of the plank, l = 1.9 m
Distance between [tex]$F_2$[/tex] and the end at which [tex]$F_1$[/tex] is acting, [tex]$r_2$[/tex] = 0.49 m
Torque exerted by the weight of the plank is given by :
[tex]$\tau_w= r_{\perp} \times F$[/tex]
[tex]$=-\frac{1.9}{2} \times 14 \times 9.8$[/tex]
= -130 Nm
The torque exerted by [tex]$F_1$[/tex] is
[tex]$\tau_1= r_{1} \times F_1$[/tex]
[tex]$= 0 \times F_1$[/tex]
= 0
Torque exerted by [tex]$F_2$[/tex] is
[tex]$\tau_2= r_{2} \times F_2$[/tex]
[tex]$= 0.49 \times F_2$[/tex]
[tex]$= 0.49 F_2$[/tex]
Since the system is in equilibrium, the zero rotational acceleration occurs when the net external torque on the system is zero, i.e.
[tex]$\sum \tau = 0$[/tex]
Therefore, we get
[tex]$$\sum \tau= \tau_1+\tau_2+\tau_w[/tex]
[tex]$0= 0+0.49F_2+(-130)$[/tex]
[tex]$F_2=\frac{130}{0.49}$[/tex]
= 265 N (approx)
We know that zero linear acceleration occurs when the net external force is zero on the system to achieve equilibrium, i.e.
[tex]$\sum F = 0$[/tex]
[tex]$\sum F = -F_1+F_2-mg=0$[/tex]
[tex]$F_1=F_2-mg$[/tex]
= 265 - (14 x 9.8)
= 128 N (approx)
Related Questions
A child moving at constant velocity carries a 2 N ice-cream cone 1 m across a level surface. What is the net work done on the ice-cream cone?
Answers
Answer:
2 Joule
Explanation:
Work=force *dISPLACMENT
2N*1M
2 JOUL
A bird is standing on an electric transmission line carrying 3000 A of current. A wire like this has about 3.0 x 10-5 22 of resistance per meter. The bird's feet are 6 cm apart. The bird itself has a resistance of about 4 x 105 12. The bird experiences a potential difference of 0.0054 V. What current goes through the bird?
Answers
Answer:
13.5 x 10^-9 A
Explanation:
Yes
Which of the following means that an
image is real?
A. +do
B. +di
c. -di
D.-do
Answers
Answer:
B
Explanation:
is it possible to have rainbows during the fine sunny day? Explain your answer.
Answers
Answer:
As long as there is rain, a rainbow is possible. Rain is possible on a sunny day, and is known as a sunshower.The rainbow can be observed in a sunny day if the water droplets are present in air and the sun rays pass through it reaches the eye of the observer. In this situation, the observer can see a rainbow.
or
If you happened to look up at the sky this past weekend, you might have noticed a rare and beautiful sight: iridescent rainbow clouds, but not a drop of rain in sight. This phenomenon is known, fittingly, as cloud iridescence or irisation. The effect is not unlike seeing a rainbow painted on the clouds.
The illustration shows ?
A)open circuit
B)broken circuit
C)series circuit
D)parallel circuit
Answers
Answer:
D)parallel circuit
Explanation:
the components are placed parallel from eachother
A system has two possible energy states, E0 and E1 (with E1 > E0). If the difference between these energy states grows (E0 and E1 get further apart while the temperature stays constant), then the ratio of the number of particles in state E0 over the number of particles in state E1 will:__________
Answers
Answer:
The number of particles in state E0 over the number of particles in state E1 will reduce
Explanation:
E0 represents the ground level state when all the particles have same energy level.
E1 represents excited state in which only a few particle reaches
E0 and E1 get further apart means that the energy difference between the two level increases.
Thus, the number of particles in state E0 over the number of particles in state E1 will reduce.
A woman is 160160cm tall. What is the minimum vertical length of a mirror in which she can see her entire body while standing upright
Answers
This question is incomplete, the complete question is;
A woman is 160cm tall. What is the minimum vertical length of a mirror in which she can see her entire body while standing upright.
Hint: Consider the ray diagram below, of the rays that enable her to see her feet and the top of her head.
Use what you know about the law of reflection, together with a bit geometry.
The missing Image is uploaded along this answer below.
Answer:
the minimum vertical length of a mirror in which she can see her entire body while standing upright is 80 cm
Explanation:
Given the data in the question and illustrated in the image below,
From image 2;
The distance from the woman's eyes to the top of her head is represented as b and a represent the distance from her eyes to her feet.
Therefore, since her height is 160 cm
a + b = 160 ------ let this be equation 1
i.e AD + DG = 160 cm
Now, from the same image 2, we will notice that triangle ABC and tringle CBD are similar, so
∠ABC = ∠CBD
AC = CD
since AD = a and AC + CD = A
AC = CD = a/2
Also, triangle DEF and FEG are si,ilar
∠DEF = ∠FEG
so
DF = FG
since DG = b and DF + FG = b
DF = b/2
so the minimum vertical length of a mirror in which the woman can see her entire body while standing upright will be;
⇒ a/2 + b/2
⇒ a + b / 2
from equation 1, a + b = 160
so
⇒ a + b / 2 = 160 / 2 = 80
Therefore, the minimum vertical length of a mirror in which she can see her entire body while standing upright is 80 cm
The minimum vertical length of a mirror in which she can see her entire body while standing upright is 80 cm.
What is the minimum vertical length?The minimum vertical length of a mirror in which she can see her entire body while standing upright is calculated as follows;
u + v = 160 cm
where;
u is the image heightv is the object heightFor mirror, u = v
2u = 160 cm
u = 160 cm/2
u = 80 cm
Learn more about image height here: https://brainly.com/question/10501143
#SPJ5
List some distinguishing features of metamorphic rocks?
Answers
Answer:
Metamorphic rocks were once igneous or sedimentary rocks, but have been changed (metamorphosed) as a result of intense heat and/or pressure within the Earth's crust. They are crystalline and often have a “squashed” (foliated or banded) texture.
Explanation:
:)
1-The amount of heat required to raise the temperature
of 1 g of a substance by degree celsius is
one
Answers
Answer:
• specific heat
1 Answer. The specific heat is the amount of heat required to raise the temperature of 1 g of substance by one degree Celsius or one Kelvin
What is the acceleration of a car going from a starting speed of 12 m/s to 25 m/s in 6 seconds? *
Answers
Answer:
[tex]v = u + at \\ 25 = 12 + a6 \\ 13 = 6a \\ a = 2.16 \\ [/tex]
a=2.16ms^-2
True False: Marke each statement as true or false.
shift
1. Light intensity affects the rate of photosynthesis.
in
2. Energy is required by all organisms for life.
3. The ability of a plant to repair tissue depends on respiration.
4. The gas needed for photosynthesis is carbon dioxide (CO2).
5. Plants only carry on photosynthesis, not respiration.
6. Respiration can occur without photosynthesis.
Answers
Answer:
1) true 2) true 3) true 4) true 5) false 6) false
Explanation:
what happen to the total energy of a moving object if all the applied forces are conserved
Answers
Answer:
As objects move around over time, the energy associated with them—e.g., kinetic, gravitational potential, heat—might change forms, but if energy is conserved, then the total will remain the same. Conservation of energy applies only to isolated systems.
thenks and pls mark me barinliestt :))
What is the electric field strength 7.50 x 10E-1 meters from a 2.8 x 10 E-3 C charged object?
Answers
Answer:hi
Explanation:
Why do we never notice quantization?
a. because the fundamental quanta are so large
b. because the fundamental quanta are so small
C. because we are moving quickly relative to such objects
d because we are moving slowly relative to such objects
Answers
Answer:
B
Explanation:
quantization of energy is only seen in atoms
Two loudspeakers in a plane are 2.0 m apart and in phase with each other. Both emit 700 Hz sound waves into a room where the speed of sound is 341 m/s. A listener stands 5.0 m in front of the loudspeakers and 2.0 m to one side of the center line. Is the interference at this point completely constructive, completely destructive, or in between
Answers
Answer:
interference is between destructive and constructive
Explanation:
The interference of two sound waves periodicity in phase by the speakers is
Δr = [tex]\frac{\phi }{2\pi } \ \lambda[/tex]
in this case they indicate that the frequency is f = 700 Hz, the wave speed is
v =λ f
λ = v / f
λ = 341/700
λ = 0.487 m
Let's use the Pythagorean theorem to find the distance that each wave travels
r₁ = [tex]\sqrt{x^2 + y^2}[/tex]
let's measure the distance from speaker 1
r₁ = [tex]\sqrt{5^2 + 1^2}[/tex]
r₁ = 5,099 m
the distance from the second speaker
r₂ = \sqrt{x^2 + y^2}
r₂ = [tex]\sqrt{5^2 +3^2}[/tex]
r₂= 5.831 m
the difference in the way is
Δr = r₂ -r₁
Δr = 5,831 - 5,099
Δr = 0.732 m
[tex]\frac{ \phi }{2\pi }[/tex] = Δr /λ
\frac{ \phi }{2\pi } = 0.732 / 0.487
\frac{ \phi }{2\pi } = 1.50
this is the phase difference this phase difference is approximately
Ф= [tex]\frac{\pi }{2}[/tex] =1.57,
so the interference is between destructive ( Ф = π) and constructive (Ф=2π)
Consider a 30-cm-diameter hemispherical enclosure. The dome is maintained at 600 K, and heat is supplied from the dome at a rate of 65 W while the base surface with an emissivity of 0.55 is maintained at 400 K. Determine the emissivity of the dome.
Answers
Answer:
[tex]\epsilon_2=0.098[/tex]
Explanation:
Diameter [tex]d=30cm=0.3m[/tex]
Temperature [tex]T=600k[/tex]
Rate of supply [tex]r=65W[/tex]
Emissivity of base surface [tex]\in_b =0.55[/tex]
Temperature at base [tex]T_b=400k[/tex]
Generally the equation for Area of base surface is mathematically given by
[tex]A_b=\frac{\pi}{4}d^2[/tex]
[tex]A_b=\frac{\pi}{4}0.3^2[/tex]
[tex]A_b=0.0707m^2[/tex]
Generally the equation for Area of Hemispherical dome is mathematically given by
[tex]A_h=\frac{\pi}{2}d^2[/tex]
[tex]A_h=\frac{\pi}{2}0.3^2[/tex]
[tex]A_h=0.1414m^2[/tex]
Since base is a flat surface
[tex]F_{11}+F_{12}=1[/tex]
[tex]F_{11}=0[/tex]
Therefore
[tex]F_{12}=1[/tex]
[tex]A_b=0.0707m^2[/tex]
Generally the equation for Net rate of radiation heat transfer between two surfaces is mathematically given by
[tex]Q_{21}=-Q_{12}[/tex]
[tex]Q_{21}=\frac{\sigma(T_1^4-T_2^4)}{\frac{1-\epsilon}{A_b\epsilon_1} +\frac{1}{A_bF_{12}} +\frac{1-\epsilon_2}{A_h*\epsilon_2} }[/tex]
Where
[tex]\sigma=5.67*10^{-8}[/tex]
Therefore
[tex]65=\frac{(5.67*10^{-8}(400^4-600^4))}{\frac{1-0.55}{0.0707*0.55}+\frac{1}{0.0707}+\frac{1-\epsilon_2}{0.1414*\epsilon_2}}[/tex]
[tex]\epsilon_2=0.098[/tex]
[tex]\epsilon_2 \approx 0.1[/tex]
Therefore the emissivity of the dome is
[tex]\epsilon_2=0.098[/tex]
A certain organ pipe, open at both ends, produces a fundamental frequency of 288 Hz in air. Part A If the pipe is filled with helium at the same temperature, what fundamental frequency tHe will it produce
Answers
Answer:
773.25 Hz
Explanation:
Concept : In an open organ pipe in fundamental mode of vibration
wave length of wave λ = 2L
where L is length of the pipe
frequency = velocity of sound / λ
Given values: fundamental frequency = 288 Hz
fluid is air. velocity of sound = 340 m/s
⇒ 288 = 340/2L
⇒L = 59.02 cm
The point to be noted is if the pipe is filled with helium initially at the same temperature, there would be change in the sound velocity .Then, frequency of note produced will also be changed .
We know that velocity of sound is inversely proportional to square root of molar mass of gas
velocity of sound in air / velocity of sound in helium = Square root of (Molar mass of Helium/ molar mass of air)
[tex]\frac{V_a}{V_{He}} = \sqrt{\frac{4}{28.8} } \\\frac{340}{V_{He}} =0.3725\\V_{He} =912.5 m/s[/tex]
Now, frequency = velocity of sound / λ
= 912.75 / (2 x 0.5902)
= 773.25 Hz
7) The coefficient of performance (COP) of a refrigerator is defined as the ratio of A) the heat removed from the inside to the heat expelled (dismissed) to the outside. B) the heat expelled (dismissed) to the outside to the heat removed from the inside. C) the heat removed from the inside to the work done to remove the heat. D) the heat expelled (dismissed) to the outside to the work done to remove the heat
Answers
Answer:
C) the heat removed from the inside to the work done to remove the heat.
Explanation:
Refrigerator is a heat engine working in reverse direction . Heat from cold source is taken out , some work is done to remove them and total heat and work energy is thrown into outside surrounding .
If q heat is taken out and W is work done to get this heat out .
coefficient of performance ( COP ) = q / W .
Hence C ) is the right choice .
The springs of a 1500 kg car compress 5.00 mm when its 68 kg driver gets into the driver's seat. Part A If the car goes over a bump, what will be the frequency of oscillations
Answers
Answer:
the frequency of the oscillation is 1.5 Hz
Explanation:
Given;
mass of the spring, m = 1500 kg
extention of the spring, x = 5 mm = 5 x 10⁻³ m
mass of the driver = 68 kg
The weight of the driver is calculated as;
F = mg
F = 68 x 9.8 = 666.4 N
The spring constant, k, is calculated as;
k = F/m
k = (666.4 N) / (5 x 10⁻³ m)
k = 133,280 N/m
The angular speed of the spring is calculated;
[tex]\omega = \sqrt{\frac{k}{m} } \\\\\omega = \sqrt{\frac{133280}{1500} } = 9.426 \ rad/s[/tex]
The frequency of the oscillation is calculated as;
ω = 2πf
f = ω / 2π
f = (9.426) / (2π)
f = 1.5 Hz
Therefore, the frequency of the oscillation is 1.5 Hz
An electrical insulator is a material that:
A) contains no charge
B) does not allow electrons to flow
C) has more protons than electrons
D) must be a crystal
Answers
Answer:
Option B is appropriate for this question
True or False? To observe physical properties in matter, the matter must change into a new substance.
Answers
Explanation:
It just is trust me
the process where water vapor into the atmosphere is changed back into liquid water
Answers
Answer:
Condensation is the process by which water vapor in the air is changed into liquid water. Condensation is crucial to the water cycle because it is responsible for the formation of clouds.
Explanation:
just is
Why does carpet produce static electricity more than hardwood floors?
Answers
Answer:
The carpet has a buildup of electrons in it that get released onto your body when you rub across the floor while the hardwood doesn't have electrons built up inside of it.
Explanation:
I study that
A boat that can travel at 4.60 km/h in still water crosses a river with a current of 1.80 km/h. At what angle must the boat be pointed upstream to travel straight across the river
Answers
Answer:
The angle the boat must be pointed upstream is 69⁰
Explanation:
Check the image uploaded for the diagram;
Given;
speed of the boat on still water, = 4.6 km/h
speed of the boat on a river with current, = 1.8 km/h
The angle the boat must be pointed upstream is calculated as follows
[tex]tan(\theta) = \frac{4.6}{1.8} \\\\tan(\theta) = 2.556\\\\\theta = tan^{-1}(2.556)\\\\\theta = 68.63^0\\\\\theta = 69^0[/tex]
Suppose you have a 6.0 V motorcycle battery that can move 3,000 C of charge. How much energy does it deliver
Answers
Answer:
1.8*10^4 Joules
Explanation:
Given data
Voltage= 6volts
Q= 3000 C
We know that the energy due to a point charge is
Pe= QV
substitute
Pe= 3000*6
Pe=18000
Pe= 18000Joules
Pe= 1.8*10^4 Joules
8. Which of Newton’s Laws would allow a passenger to fly right out of their seat if they do not have a seat belt on and a
car suddenly stops.
A) The First Law C) The Third Law
B) The Second Law D) The Fourth Law
Answers
The answer is A The first law
PLS HELP!! Our eyes perceive colors because of differences in which of the following properties of light?
Amplitude
Brightness
Wavelength
Source
Answers
Answer:
Your answer is wavelength
A sphere has a surface uniformly charged with 3.30 C. At what distance from its center is the potential 4.50 MV
Answers
Answer:
r = 6.6 x 10³ m = 6600 m
Explanation:
The potential at a distance from a charged sphere can be given as follows:
[tex]V = \frac{kq}{r}\\\\r = \frac{kq}{V}[/tex]
where,
r = distance = ?
k = Colomb Constant = 9 x 10⁹ Nm²/C²
q = charge on sphere = 3.3 C
V = potential = 4.5 MV = 4.5 x 10⁶ V
Therefore,
[tex]r = \frac{(9\ x\ 10^9\ Nm^2/C^2)(3.3\ C)}{4.5\ x\ 10^6\ V}[/tex]
r = 6.6 x 10³ m = 6600 m
The diagram below shows a person swinging a hammer.
Which position has the least amount of kinetic energy?
A-1
B-2
C-3
D-4
Answers
A magnetic field of 0.27 T exists in the region enclosed by a solenoid that has 599 turns and a diameter of 9.29 cm. Within what period of time must the field be reduced to zero if the average magnitude of the induced emf within the coil during this time interval is to be 12.8 kV
Answers
Answer: [tex]8.54\times 10^{-5}\ s[/tex]
Explanation:
Given
The initial magnetic field is [tex]B=0.27\ T[/tex]
No of turns [tex]N=599\ \text{turns}[/tex]
Diameter of the solenoid [tex]d=9.29\ cm[/tex]
Induced EMF [tex]E=12.8\ kV[/tex]
Induced emf is the product of no of turns and rate of change of flux.
[tex]\Rightarrow E=-N\cdot \dfrac{\Delta \phi }{\Delta t}\\\\\Rightarrow E=-N\cdot \dfrac{\Delta (B\cdot A)}{\Delta t}\\\\\Rightarrow E=-NA\cdot \dfrac{\Delta B}{\Delta t}\\\\\text{Insert the values}\\\\\Rightarrow 12.8=-599\times \pi r^2\cdot \dfrac{(0-B)}{\Delta t}\\\\\Rightarrow \Delta t=\dfrac{599\times \pi \times (4.64\times 10^{-2})\times 0.27}{12.8\times 10^3} \\\\\Rightarrow \Delta t=854.71\times 10^{-7}\ s\\\\\text{Taking absolute value}\\\Rightarrow \Delta t=8.54\times 10^{-5}\ s[/tex]