A 15 m uniform ladder weighing 500 N rests against a frictionless wall. The ladder makes a 60° angle with horizontal. (a) Find the horizontal and vertical forces that the earth exerts on the base of the ladder when an 800 N firefighter is 4 m from the bottom. (b) If the ladder is just on the verge of slipping when the firefighter is 9 m up, what is the coefficient of static friction between ladder and ground?
Answers
Answer:
a) F₁ = 267.3 N, N₁ = 1300 N, b) μ = 0.324
Explanation:
For this exercise we use the rotational equilibrium condition, we have a reference system is the floor and the anticlockwise rotations as positive, in the adjoint we can see a diagram of the forces
let's use subscript 1 for the ladder and 2 for the firefighter
∑ τ = 0
-W₁ x₁ - W₂ x₂ + N₁ y = 0
N₁ = [tex]\frac{W_1 x_1 + W_2 x_2}{y}[/tex] (1)
the center of mass of the ladder is at its geometric center,
d = L / 2 = 15/2 = 7.5 m
cos 60 = x₁ / d₁
x₁ = d₁ cos 60
x₁ = 7.5 cos 60
x₁ = 3.75 m
for the firefighter d₂ = 4 m
cos 60 = x₂ / d₂
x₂ = d₂ cos 60
x₂ = 4 cos 60 = 2 m
for the fulcrum d₃ = 15 m
sin 60 = y / d₃
y = d₃ sin 60
y = 15 sin 60
y = 13 m
we look for the Normal by substituting in equation 1
N₂ = [tex]\frac{500 \ 3.75 \ + 800 \ 2}{13}[/tex]
N₂ = 267.3 N
now let's use the translational equilibrium relations
X axis
F₁ - N₂ = 0
F₁ = N₂
F₁ = 267.3 N
Axis y
N₁ - W₁ -W₂ = 0
N₁ = W₁ + W₂
N₁ = 500 + 800
N₁ = 1300 N
b) for this case change the firefighter's distance d₂ = 9 m
x₂ = 9 cos 60
x₂ = 4.5 m
we substitute in 1
N₂ = \frac{500 \ 3.75 \ + 800 \ 4.5}{13}
N₂ = 421.15 N
of the translational equilibrium equation on the x-axis
fr = F₁ = N₂
fr = 421.15 N
friction force has the expression
fr = μ N
in this case the reaction of the Earth to the support of the ladder is N1 = 1300N
μ = fr / N₁
μ = 421.15 / 1300
μ = 0.324
Related Questions
Which is an advantage of storing data digitally?
A. It is easy to change the data if you have the right computer
programs.
B. It is easy to copy a computer virus to a device along with the data.
C. The quality of copies decrease as more copies are made.
D. Other people can access personal data from unsecured devices.
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Answer:
A
Explanation:
Because I said so
Answer:
A
Explanation:
i took the test and got it right please mark me ❤️
What inspired Ronald McNair to do science
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Answer:
While working as a staff physicist at hughes Research Laboratories McNair learned that the National Aeronautics and Space Administration (NASA) was looking for scientist to join the shuttle program;)
how is friction involved in the movement of space
Answers
Answer:
Friction can stop or slow down the motion of an object.
Explanation:
The slowing force of friction always acts in the direction opposite to the force causing the motion.
Describe the political actions that led to successful conservation in both stories.
Answers
Answer:
The political actions that led to successful conservation in both stories were what they call an FC company that makes the forest industry true. They make it out of a factory and it can make it very successful and accomplished.
Explanation:
How do projectors project the color black?
Answers
Answer:
Projectors do not project the color black. This makes sense since black is really the absence of light, and you can't project something that does not exist. When a projector sends a beam of light on to a wall or a projector screen so that an image is formed on the wall or screen, the parts of the image that look black are really a very dim white color (which we sometimes call gray). - wtamu
Answer is:
Projectors do not project the color black.
Which subatomic particle is NOT found in the nucleus of an atom? *
protons
neutrons
electrons
Answers
Answer:
Electrons
Explanation:
Only Protons and Neutrons are found in the nucleus
which particles do not affect the stability of the atom
Answers
20charachters
Electrons are the particle pr4esent inside the atom that does not affect the stability of the atom,
What is radioactivity?The ability of some unstable atoms to emit nuclear radiation spontaneously, typically in the form of alpha or beta particles frequently accompanied by gamma rays, is known as radioactivity.
An overabundance of neutrons or protons can make the nucleus of an atom unstable.
A radioactivity atom will try to become stable by extruding other particles, such as protons or neutrons, or by releasing energy in various ways.
Thus, Electrons are the particle present inside the atom that does not affect the stability of the atom,
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A ball is rolling with a constant acceleration of 13 m/s starting from rest. How long will it take to increase its velocity to a final speed of 62 m/s?
Answers
Time taken : 4.77 s
Further explanationGiven
a = 13 m/s²
vf = final velocity = 62 m/s
Required
time taken
Solution
An equation of uniformly accelerated motion
[tex]\large {\boxed {\bold {x=xo+vo.t+\frac {1} {2} at ^ 2}}}[/tex]
vf = vo + at
vf² = vo² + 2a (x-xo)
x = distance on t
vo / vi = initial speed
vt / vf = speed on t / final speed
a = acceleration
Input the value :
vo =0 ⇒from rest
vf=at
62 m/s = 13 m/s².t
t = 62 : 13
t = 4.77 s
Pulling a rubber band back and then letting it fly across the room is an example of
A. converting energy to work
B. converting elastic energy to gravitational
C. converting kinetic energy to potential
Answers
Answer:
b
Explanation:
because a elastic band uses elastic energy
Suppose a car is traveling at 22.8 m/s, and the driver sees a traffic light turn red. After 0.404 s has elapsed (the reaction time), the driver applies the brakes, and the car decelerates at 9.00 m/s2. What is the stopping distance of the car, as measured from the point where the driver first notices the red light?
Answers
Answer:
38.09 m
Explanation:
We'll begin by calculating the distance travelled by the car during the reaction time. This can be obtained as follow:
Reaction time (tᵣ) = 0.404 s
Initial velocity (u) = 22.8 m/s,
Distance travelled during the reaction time (sᵣ) =?
sᵣ = utᵣ
sᵣ = 22.8 × 0.404
sᵣ = 9.21 m
Next, we shall determine the distance travelled by the car when the brake was applied. This can be obtained as follow:
Initial velocity (u) = 22.8 m/s
Acceleration (a) = –9 m/s² (since the car is decelerating)
Final velocity (v) = 0 m/s
Distance travelled when the brake was applied (s₆) =?
v² = u² + 2as₆
0² = 22.8² + (2 × –9 × s₆)
0 = 519.84 – 18s₆
Collect like terms
0 – 519.84 = –18s₆
–519.84 = –18s₆
Divide both side by –18
s₆ = –519.84 / –18
s₆ = 28.88 m
Finally, we shall determine the stopping distance of the car, as measured from the point where the driver first notices the red light. This can be obtained as follow:
Distance travelled during the reaction time (sᵣ) = 9.21 m
Distance travelled when the brake was applied (s₆) = 28.88 m
Stopping distance =?
Stopping distance = sᵣ + s₆
Stopping distance = 9.21 + 28.88
Stopping distance = 38.09 m
A wheelbarrow is pushed 10 meters with a force of 75 N for 30 seconds. What is the work done?
How much power is needed?
Answers
Power= work done/ time taken.
Work done = 75N x 10m
= 750Nm/ 750J( Joules)* joules is the SI unit of work.
Power is the rate at which work is done. Suppose two men were carrying a heavy box, man A has a force of 10N , man B has a force of 10N and both carries the box of a distance 3m. Both have done the same work. But if suppose man A takes 2 seconds to carry the box while man B takes 3 seconds, their power needed are different.
Man A , power= 30J/ 2s which is 15 joules per second ( SI unit of power is “watts”)
Man B, power= 30J/ 3s which is 10 joules per second. MAN A HAS MORE POWER.
so, the work done for the wheelbarrow is 750J, divide it by the time taken( 30 seconds) 750J/30s= 25 J/s. <— this is the power needed.
During a storm, a car traveling on a level horizontal road comes upon a bridge that has washed out. The driver must get to the other side, so he decides to try leaping the river with his car. The side of the road the car is on is18.0 m above the river, while the opposite side is only1.8 m above the river. The river itself is a raging torrent69.0 m wide.Part AHow fast should the car be traveling at the time it leaves the road in order just to clear the river and land safely on the opposite side?Part BWhat is the speed of the car just before it lands on the other side?
Answers
Answer:
Part A: The speed the car should be travelling when leaping the river is approximately 37.948 m/s
Part B: The speed of the car just before it lands is approximately 41.92345 m/s
Explanation:
The parameters of the car attempting leaping the river are;
The height of the car over the river = 18 m
The height of the opposite side of the bridge above the river = 1.8 m
The width of the river, x = 69.0 m
Part A
The time, 't' it would take the car to fall from 18 m above the river to 1.8 m above the river is given as follows;
t = √(2·h/g)
Where;
h = The height of the fall = 18 m - 1.8 m = 16.2 m
g = The acceleration due to gravity = 9.8 m/s²
∴ t = √(2×16.2 m/(9.8 m/s²)) = (9/7)·√2 s
The horizontal speed, 'vₓ', with which the car should be travelling at the time it leaves the road in order just to clear the river and land safely on the opposite side is given as follows;
vₓ = x/t = 69.0 m/((9/7)·√2 s) = (161/6)·√2 m/s ≈ 37.948 m/s
The horizontal speed the car should be travelling when leaping the river, vₓ ≈ 37.948 m/s
Part B;
The vertical velocity of the car is given as follows;
[tex]v_y[/tex]² = [tex]u_y[/tex]² + 2·g·h
∴ [tex]v_y[/tex]² =2·g·h = 2 × 9.8 m/s² × 16.200 m = 317.52m²/s²
[tex]v_y[/tex] = √(317.52 m²/s²) = (63/5)·√2 ≈ 17.819 m/s
The magnitude of the speed of the car, 'v', just before it lands is given using Pythagoras' theorem for resultant vectors as follows;
v = √([tex]v_y[/tex]² + vₓ²) = √(317.52 m²/s² +((161/6)·√2 m/s)²) ≈ 41.92345 m/s
The speed of the car just before it lands, v ≈ 41.92345 m/s.
true or false solubility can be used to identify an unknown substance
Answers
True
Iron has a specific heat of o.45 J/g °C. Removing -1.16 E 2 J of energy lowered the temperature of iron from 89 °C to 26.41 °C. What was the mass of the iron?
Answers
Answer:
m = 4.11 grams
Explanation:
Given that,
The specific heat of Iron, c = 0.45 J/g°C
Heat removed, [tex]Q=1.16\times 10^2\ J[/tex]
Initial temperature, [tex]T_i=89^{\circ} C[/tex]
Final temperature, [tex]T_f=26.41^{\circ} C[/tex]
We need to find the mass of the iron. We know that the heat removed in terms of specific heat is given by :
[tex]Q=mc\Delta T\\\\m=\dfrac{Q}{c\Delta T}\\\\m=\dfrac{-1.16\times 10^2}{0.45\times (26.41-89)}\\\\m=4.11\ g[/tex]
So, the mass of the iron is 4.11 grams.
Why can’t a real machine ever have 100% efficiency
Answers
Answer:
Almost all machines require energy to offset the effects of gravity, friction, and air/wind resistance. Thus, no machine can continually operate at 100 percent efficiency.
INT Raindrops acquire an electric charge as they fall. Suppose a 2.0-mm-diameter drop has a charge of 12 pC; these are both very common values. In a thunderstorm, the electric field under a cloud can reach 15,000 N/C, directed upward. For a droplet exposed to this field, how do the magnitude and direction of the electric force compare to those of the weight force
Answers
Answer:
W = 2.3 10² [tex]F_{e}[/tex]
Explanation:
The force of the weight is
W = m g
let's use the concept of density
ρ= m / v
the volume of a sphere is
V = [tex]\frac{4}{3}[/tex] π r³
V = [tex]\frac{4}{3}[/tex] π (1.0 10⁻³)³
V = 4.1887 10⁻⁹ m³
the density of water ρ = 1000 kg / m³
m = ρ V
m = 1000 4.1887 10⁻⁹
m = 4.1887 10⁻⁶ kg
therefore the out of gravity is
W = 4.1887 10⁻⁶ 9.8
W = 41.05 10⁻⁶ N
now let's look for the electric force
F_e = q E
F_e = 12 10⁻¹² 15000
F_e = 1.8 10⁻⁷ N
the relationship between these two quantities is
[tex]\frac{W}{F_e}[/tex] = 41.05 10⁻⁶ / 1.8 10⁻⁷
\frac{W}{F_e} = 2,281 10²
W = 2.3 10² [tex]F_{e}[/tex]
therefore the weight of the drop is much greater than the electric force
Answer this and you get 100 points
You better answer it quick though
Answers
Answer what? Apologies, but I don't see anything. (。>︿<)
Do You think History is the most important subject that deserves first place? Do you see a way that learning history could assist you in your future career?
Answers
yes
Explanation:
history is an important class and it helps to you understand what went on in the past so that we can learn from our mistakes and help us grow
HELP ASAP PLS
A balloon with a positive charge will stick to a wall that has a negative charge.
What force causes this?
A. Gravity
B. Electric force
C. Magnetic force
D. Air gesistance
Answers
The reason that the balloon will stick to the wall is because the negative charges in the balloon will make the electrons in the wall move to the other side of their atoms (like charges repel) and this leaves the surface of the wall positively charged.
If I’m wrong I’m sorry :(
Astronomers study the electromagnetic radiation emitted by distant stars and planets to determine things like: how far away they are, their temperatures and speed, etc. Based on what you learned in this class, explain why the NASA Hubble Space Telescope is better for observing the electromagnetic radiation emitted from stars and planets at 560 km above sea level compared to the Keck telescope in Hawaii, which is 4 km above sea level
Answers
Answer:
This same Hawaii telescope, which would be 4 km across water level, can't provide an appropriate version of distanced planetary bodies. A further overview is provided below.
Explanation:
The surface area of that same earth's orbit seems to be approximately 480 km heavy. The atmosphere isn't translucent to the only certain wavelength range of the radioactivity. Not because all-stars, as well as gliders, emit specific wavelengths, but several of them generate ultraviolet as well as infrared. Those same radiations have either been mediated primarily as well as passes through the atmosphere. Due to the Blockage, they can't even be interpreted with such a similar quality unless the telescope would be positioned throughout the portion of the atmosphere.6 An object can never have
A. a positive speed.
B. a negative speed.
C. a positive velocity.
D. a negative velocity.
Answers
Answer:
B
Explanation:
Speed is the magnitude of the velocity vector, so it can never be negative.
An object can never have a negative velocity. Therefore, option (D) is correct.
What is velocity?Velocity is a vector quantity that describes an object's speed and direction of motion. If an object is moving in a positive direction, it has a positive velocity. If it is moving in the opposite direction, it has a negative velocity.
However, an object can never have a negative speed. Speed is a scalar quantity that describes an object's rate of motion, and it is always positive. The speed of an object can be positive or negative, depending on the direction of its velocity, but the magnitude of its speed is always positive.
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Peter, a 100 kg basketball player, lands on his feet after completing a slam dunk and then immediately jumps up again to celebrate his basket. When his feet first touch the floor after the dunk, his velocity is 5 m/s downward; when his feet leave the floor 0.50 s later, as he jumps back up, his velocity is 4 m/s upward. a. What is the impulse exerted on Peter during this 0.50 s
Answers
Answer:
Explanation:
Impulse = change in momentum
Initial momentum = mass x initial velocity = 100 x 5 = 500 kg m/s
final momentum = mass x final velocity = 100 x - 4 = -400 ( - ve sign due to reversal of direction )
change in momentum = final momentum - initial momentum
= - 400 - 500 = - 900 kg m/s .
As it is - ve , it acts upwards .
So magnitude of impulse on Perter = 900 kg m/s
you describe a friend’s position by including distance, direction, and what other term?
Answer choices:
A. Acceleration
B.displacement
C.Average speed
D. Reference point
PLEASE HELP I NEED THIS IN AN HOUR
Answers
Answer:
Acceleration
Explanation:
Answer: Acceleration
Explanation:
When the material in the mantle cools off near the surface then sinks
down towards the core and get heated again and rises back towards the
surface it is called?
Condensation
О
The water cycle
O
Convection currents
О
Apples and Bananas.
PLEASE HELP THIS IS URGENT ITS FOR A TEST
Answers
Answer:
convection currents
Explanation:
50 points Two waves combine with constructive interference. What must be true of the
combined wave that forms?
A. It has a lower frequency than that of the original waves.
B. It has a higher amplitude than that of the original waves.
C. It has a higher frequency than that of the original waves.
D. It has a lower amplitude than that of the original waves.
Answers
Answer:
it has a higher amplitude than that of the original waves
Explanation:
trust me its right
The two waves combined with constructive interference have a higher amplitude than the original wave.
Which wave has the highest amplitude?High energy waves are characterized by high amplitude. Low energy waves are characterized by their small amplitude. As explained in Lesson 2, wave amplitude is the maximum amount of particle movement on a medium from a resting position.
What are superposition and interference?Superposition is a combination of two waves in the same place. Constructive interference occurs when two identical waves interfere in phase. Destructive interference occurs when two identical waves are exactly out of phase and overlap.
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A 200-N force acts on a 10-kg object. The acceleration of the object is
Answers
Suppose a cat climbs a tree to a height of 2 meters. If the cat doubles its height to 4 meters, its potential energy will
1)not change
2)reduce to halve
3)double
4)quadruple
Answers
If h doubles Ep=m*g*2h
Meaning Ep=1*1*2
Ep=2
So 3)potential energy doubles.
Violet pulls a rake horizontally on a frictionless driveway with a net force of 2.0 N for 5.0 m.
How much kinetic energy does the rake gain?
Answers
Answer:
10 J.
Explanation:
Given that,
Net force acting on the rake, F = 2 N
Distance moved by the rake, d = 5 m
We need to find the kinetic energy gained by the rake. We know that,
Kinetic energy = work done
So,
K = F×d
K = 2 N × 5 m
K = 10 J
So, 10 J of kinetic energy is gained by the rake.
Violet pulls a rake horizontally on a frictionless driveway with a net force of 2.0 N for 5.0 m.
How much kinetic energy does the rake gain?
Answer: 10 J
Which of these is an effect of gravity?
А
A cup placed on a table won't float away.
B
You can throw a ball or a rock up.
С
The brakes on a bike can make it stop.
D
Liquid water can become a gas.
Answers
Answer:
(A)
A cup placed on a table won't float away
A clump of soft clay is thrown horizontally from 9.80 m above the ground with a speed of 20.0 m/s. Assume it sticks in place when it hits the ground At what time will the clay hit the ground
Answers
Answer:
Explanation:
The time to hit the ground will be same as time taken to fall from the height of 9.8 m with initial vertical velocity of zero .
Considering vertical displacement
initial velocity u = 0
displacement s = 9.8 m
acceleration a = g = 9.8 m /s²
time t = ?
s = ut + 1/2 g t²
9.8 = 0 + .5 x 9.8 x t²
t² = 2
t = √2 = 1.4 s