Answer:
F = 42325.17 N
Explanation:
We are given;
Radius of hemispheres; r = 0.38 m
Inner pressure; P_i = 17 milli bar
Outside Pressure; P_o = 950 milli bar
Now, net pressure; P_net = P_o - P_i
P_net = 950 - 17
P_net = 933 milli bar
From conversion rates, we know that;
1 milli bar = 100 N/m²
Thus;
P_net = 933 × 100
P_net = 93300 N/m²
Surface Area of hemisphere; A = πr²
A = π × 0.38²
Now, formula for pressure is;
P = F/A
Where F is force.
Thus making F the subject;
F = P × A
Plug in P_net and A to get;
F = 93300 × π × 0.38²
F = 42325.17 N
1) A man leans against the wall and...
a) The man's shoulder pushes against the wall
b) The wall pushes against the man
c) Bricks in the wall push against each other
d) The ground pushes against the man, supporting him.
Answer:
I thinks its a, but its really about gravity im not sure
Explanation:
:)
Car X is travelling at 30m/s north. Its driver looks at car Y approaching on another road and he estimates it is moving at 15m/s south-west relative to his car. Calculate the velocity of car Y relative to the ground.
Answer: 22.1 m/s
Explanation:
The velocity of Car traveling 30 m/s towards the north
In vector form it is
[tex]v_x=30\hat{j}[/tex]
The velocity of car Y w.r.t X is
[tex]\Rightarrow v_{yx}=15[-\cos 45^{\circ}\hat{i}-\sin 45^{\circ}\hat{j}][/tex]
Solving this
[tex]\Rightarrow v_{yx}=v_y-v_x\\\Rightarrow v_y=v_{yx}+v_x[/tex]
putting values
[tex]\Rightarrow v_y=15[-\cos 45^{\circ}\hat{i}-\sin 45^{\circ}\hat{j}]+30\hat{j}[/tex]
[tex]\Rightarrow v_y=-10.606\hat{i}+19.39\hat{j}[/tex]
absolute velocity relative to ground is
[tex]\left | v_y\right |=\sqrt{(-10.606)^2+(19.39)^2}\\\left | v_y\right |=22.101\ m/s[/tex]
A ball is dropped off the side of a bridge,
After 1.55 S, how far has it fallen?
(Unit=m)
Answer:
Distance S = 11.77 m (Approx.)
Explanation:
Given:
Time t = 1.55 Second
Gravity acceleration = 9.8 m/s²
Find:
Distance S
Computation:
S = ut + (1/2)(g)(t)²
S = (0)(1.55) + (1/2)(9.8)(1.55)²
S = (0)(1.55) + (1/2)(9.8)(1.55)²
Distance S = 11.77 m (Approx.)
A truck with a mass of 1370 kg and moving with a speed of 12.0 m/s rear-ends a 593 kg car stopped at an intersection. The collision is approximately elastic since the car is in neutral, the brakes are off, the metal bumpers line up well and do not get damaged. Find the speed of both vehicles after the collision in meters per second.
Answer:
speed of car after collision, v2 =16.1 m/s and of the truck, v1 = 4.6 m/s
Explanation:
Given:
mass of truck M = 1370 kg
speed of truck = 12.0 m/s
mass of car m = 593 kg
collision is elastic therefore,
Applying law of momentum conservation we have
momentum before collision = momentum after collision
1370×12 + 0( initially car is at rest) = 1370×v1+ 593×v2 ....(i)
Also for a collision to be elastic,
velocity of approach = velocity of separation
12 -0 = v2-v1 ....(ii)
using (i) and (ii) we have
So speed of car after collision, v2 =16.1 m/s and of the truck, v1 = 4.6 m/s
Based on the definition of weather, ____________, is the basic difference climate and weather.
a)precipitation
b)condensation
C)time
D)jet stream
Answer:
The answer is C. time. Please mark as brainliest.
Fossil clues are one of the _____________ clues that support the theory of continental drift.
A. crust B. resource C. climate D. rock
Answer:
a
Explanation:
I think don't get mad if I'm wrong
Suppose that white light strikes a flat piece of flint glass in air, coming in at an angle of 60 degrees to the surface (30 degrees from the normal or perpendicular). The index of refraction of this dense glass for red light is 1.710, for green light is 1.723, and for blue light is 1.735. What is the order of colors you would see in the refracted light inside the glass as they leave the surface
Answer:
The order of the light starting from the light closest to the normal line is
Blue light, followed by green ight and then lastly red light
Explanation:
White light travels from one medium to another such as from air to glass is refracted according to Snell's law as follows
n₁·sin(θ₁) = n₂·sin(θ₂)
The given parameters of the white light are;
The angle the incident (incoming) light makes with the surface = 90°
The angle of incidence of the light, θ₁ = 30°
The index of refraction of red light for the glass, n₂ = 1.710
The index of refraction of green light for the glass, n₃ = 1.723
The index of reaction of blue light for the glass, n₄ = 1.735
The refractive index of air, n₁ = 1
The angle of refraction of the red light, θ₂ is given as follows;
1 × sin(30°) = 1.710 × sin(θ₂)
sin(θ₂) = 1 × sin(30°)/1.710
θ₂ = sin⁻¹(1 × sin(30°)/1.710) ≈ 17°
The angle of refraction (to the surface's normal line) of the red light, θ₂ ≈ 17°
The angle of refraction of the green light, θ₃ is given as follows;
1 × sin(30°) = 1.723 × sin(θ₃)
sin(θ₃) = 1 × sin(30°)/1.723
θ₃ = sin⁻¹(1 × sin(30°)/1.723) ≈ 16.869°
The angle of refraction of the green light, θ₃ ≈ 16.869°
The angle of refraction of the green light, θ₄ is given as follows;
1 × sin(30°) = 1.723 × sin(θ₄)
sin(θ₄) = 1 × sin(30°)/1.735
θ₄ = sin⁻¹(1 × sin(30°)/1.735) ≈ 16.749°
The angle of refraction of the green light, θ₄ ≈ 16.749°
The order of colors we see as the in the refracted light inside the glass as the light leave the surface are;
The red light, with an angle of refraction of approximately 17° will be furthest from the normal
The green light which has an angle of refraction of 16.869° will follow and will be intermediate between the red and the blue light
The blue light which has an angle of refraction of 16.749° will follow next and it will be closest to the normal
The order of the light from the normal line will be blue, followed by green and then red light
Suppose you are an observer standing at a point along a three-lane roadway. All vehicles in lane 1 are traveling at 50 mi/hr with a constant 5-second time headway between them. All vehicles in lane 2 are traveling at 55 mi/hr with a constant 6-second time headway between them. All vehicles in lane 3 are traveling at 60 mi/hr with a constant 10-second time headway between them. You collected spot speed data for all vehicles as they crossed your observation point for 75 minutes. After 10 minutes, vehicles in lane 1 stopped arriving, and after 30 minutes, vehicles in lane 2 stopped arriving. What is the flow and density of the observed traffic stream
Answer:
lane 3 Ф = 450 vehicles, ρ = 0.1 vehicle / s
lane 2 Ф_{average} = 300 vehicles, ρ _{average} = 6.66 10⁻² vehicles/s
lane 1 Ф_{average} = 300 vehicles, ρ_{average} = 2.66 10⁻² vehicle/s
Explanation:
Before solving this exercise we must clarify the concepts the flow is defined as the occurrence of an event in a time interval, in this case the passage of a car through time
Flux Density is the flux between unit area or unit time
Let's start by calculating the calculation for lane 3
the flow.
Let's use a direct rule of proportions (rule three) if the number of vehicles per unit of time (t₀ = 10s), for the observation time how many vehicles passed in the observation time (t_total = 75 * 60 = 4500 s)
Ф = 4500 s (1 vehicle / 10 s)
Ф = 450 vehicles
The flux density is the flux per unit area, in this case the area is not indicated, so we can define the flux density as the flux per unit of time.
ρ = 450/4500
ρ = 0.1 vehicle / s
Lane 2
we look for the flow
we can have separates the interval into two parts
* for the first t₁1 = 30 * 60 = 1800 s
Ф₁ = 1800 s (1 vehicle / 6s)
Ф₁ = 300 vehicles during t₁
* for the rest of the time t₂ = 4500-1800 = 2700 s
Ф₂ = 0
the average density is the total number of vehicles between the total time
#_ {vehicle} = 300 +0
Ф_{average) = # _vehicle
Ф_{average} = 300 vehicles in all time
The density is
ρ 1 = fi1 / t1
ρ1 = 300/1800
ρ1 = 1.66 10-1 vehicles / s
the average density is
ρ_{average} = [tex]\frac{\phi_1 + \phi_2}{ t_{total}}[/tex]
ρ _{average} = (300 +0) / 4500
ρ _{average} = 6.66 10⁻² vehicles / s
Lane 1
flow
* first time interval t₁ = 10 * 60 = 600 s
Ф₁ = 600 s (1 vehicle / 5s)
Ф₁ = 120 vehicles in interval t₁
* second interval t₂ = 4500-600 = 3900 s
Ф2 = 0
average flow
Ф = Ф1 + Ф2
Ф = 120 vehicles at all time
Density
* first interval
ρ₁ = 120/600
ρ₁ = 0.2 vehicles / s
* second interval
ρ₂ = 0
average density
ρ+{average} = 120/4500
ρ_{average} = 2.66 10⁻² vehicle/s
PLEASE ANSWER THIS WILL MARK AS BRAINLIEST PLEASE USE TRUTHFUL ANSWERS PLEASE
Which best explains why species living in Australia are found nowhere else on Earth? This is an example of Geologic Evolution.
A.
Australia has an ecosystem different from any other area on Earth.
B.
Humans have genetically altered many Australian species in laboratories.
C.
Australian species were genetically altered after a comet hit the landmass.
D.
Australia separated from other continents and species there evolved independently.
HELP PLEASE DUE IN 3 MINUTES
Answer:
Tectonic Plate Movement
Explanation:
Each continent and ocean sits on its own tectonic plate which floats on the Earths upper mantle. They move very little over time.
Answer:
tectonic plates movement
A trough is 10 meters long, 1 meters wide, and 2 meters deep. The vertical cross-section of the trough parallel to an end is shaped like an isoceles triangle (with height 2 meters, and base, on top, of length 1 meters). The trough is full of water (density 1000kg/m3 ). Find the amount of work in joules required to empty the trough by pumping the water over the top. (Note: Use g
Answer:
The amount of work required to empty the trough by pumping the water over the top is approximately 98,000 J
Explanation:
The length of the trough = 10 meters
The width of the through = 1 meter
The depth of the trough = 2 meters
The vertical cross section of the through = An isosceles triangle
The density of water in the through = 1000 kg/m³
Let 'x' represent the width of the water at a depth
x/y = 1/2
∴x = y/2
The volume of a layer of water, dV, is given as follows;
dV = 10 × y/2 × dy = 5·y·dy
The mass of the layer of water, m = ρ × dV
∴ m = 1000 kg/m³ × 5·y·dy m³ = 5,000·y·dy kg
The work done, W = m·g·h
Where;
h = The the depth of the trough from which water is pumped
g = The acceleration due to gravity ≈ 9.8 m/s²
[tex]\therefore \, W \approx \int\limits^2_0 {5,000 \times y \times 9.8 \, dy} = \left[24,500\cdot y^2 \right]^2_0 = 98,000[/tex]
The work done by the pump to pump all the water in the trough, over the top W ≈ 98,000 J
A toy projectile is fired vertically from the ground upward with a velocity of +29 meters per second. It arrives at its maximum altitude in 3.0 seconds. How high does the projectile go?
Answer:
[tex]\boxed{\text{\sf \Large 42 m}}[/tex]
Explanation:
Use height formula
[tex]\displaystyle \sf H=\frac{u^2 sin(\theta)^2}{2g}[/tex]
u is initial velocity
θ = 90° (fired vertically upward)
g is acceleration of gravity
[tex]\displaystyle \sf H=\frac{29^2 \times sin(90 )^2}{2 \times 10}=42.05[/tex]
10. A person is about to kick a soccer ball. Consider the leg and foot to be a single rigid body and that it rotates about a fixed axis through the knee joint center. Immediately prior to impact the leg and foot are in the vertical direction and the distal end of the foot has an acceleration of 10 g in the horizontal direction. The muscle force vector makes an angle of 15 degrees with the vertical and has a moment arm of 5 cm from the knee joint center. Assume the person is 1.7 m tall and has a mass of 75 kg. Find the force in the muscle
Answer:
i don't know but i hope you get it right
Explanation
Fifty grams of ice at 0◦ C is placed in a thermos bottle containing one hundred grams of water
at 6◦ C. How many grams of ice will melt? The heat of fusion of water is 333 kJ/kg and the
specific heat is 4190 J/kg · K.Immersive Reader
Answer:
7.55 g
Explanation:
Using the relation :
Δt = temperature change = (6° - 0°) = 6°
Q = quantity of heat
C = specific heat capacity = 4190 j/kg/k
1000 J = 1kJ
333 KJ = 333000 j
The quantity of ice that will melt ;
= 0.419 * 6 * 100 / 333000
= 2514000 / 333000
= 7.549 g
The mass of ice that will melt :
2.514 / 0.333
= 7.549 g
Let's assume raspberries are 10 wt% protein solids and the remainder water. When making jam, raspberries are crushed and mixed with sugar, in a 45:55 berry to sugar ratio, by mass. Afterward, the mixture is heated, boiling off water until the remaining mixture is 0.4 weight fraction water, resulting in the final product, jam. How much water, in kilograms, is boiled off per kilogram of raspberries processed
Answer:
The mass of water boiled off is [tex]0.0 \overline{185}[/tex] kg
Explanation:
The given percentage by weight of protein solids in raspberries = 10 weight%
The ratio of sugar to raspberries in ja-m = 45:55
The mass of the mixture after boiling = 0.4 weight fraction water
Let 's' represent the mass of sugar in the mixture, and let 'r' represent the mass of raspberry
The mass of raspberry, r = 1 kg
The percentage by weight of water in raspberry = 90 weight %
The mass of water in 1 kg of raspberry = 90/100 × 1 kg = 0.9 kg
The ratio of the mass of sugar to the mass of raspberry in jam = r/s = 45/55
∴ s = 1 kg × 55/45 = 11/9 kg
The mass of the mixture before boiling = 1 kg + 11/9 kg = 20/9 kg
The weight fraction of water in the remaining mixture after boiling = 0.4 weight fraction
Let 'w' represent the mass of water boiled off, we have;
(0.9 - w)/(20/9 - w) = 0.4
(0.9 - w) = 0.4 × (20/9 - w)
0.9 - w = 8/9 - 0.4·w
9/10 - 8/9 = w - 0.4·w = 0.6·w = (6/10)·w
(81 - 80)/(90) = (6/10)·w
1/90 = (6/10)·w
w = ((10/6) × 1/90) = 1/54
w = 1/54
The mass of water boiled off, w = (1/54) kg = [tex]0.0 \overline{185}[/tex] kg
Part D Here is one last question as a final check on your understanding of your work for this problem, looking at this problem as an example of the Conservation of Energy. The action in this problem begins at location A , with the block resting against the uncompressed spring. The action ends at location B, with the block moving up the ramp at a measured speed of 7.35 m/s . From A to B, what has been the work done by non-conservative forces, and what has been the change in the mechanical energy of the block-Earth system (the ramp is a part of the Earth)
Answer:
The answer is "39.95 J".
Explanation:
Please find the complete question in the attached file.
[tex]\to W_{AC}=(\mu \ m \ g \ \cos \theta ) d[/tex]
[tex]=(0.45 \times 1.60 \times 9.8 \times \cos 26^{\circ}) 6.30 \\\\=(7.056 \times \cos 26^{\circ}) 6.30 \\\\=6.34189079\times 6.30\\\\=39.95 \ J\\\\[/tex]
[tex]\therefore \\\\\bold{\Delta E =39.95 \ J}[/tex]
A spring in a toy gun has a spring constant of 10 N/m and can be compressed 4 cm.
It is then used to shoot a 1 g ball out of the gun. Find the velocity of the ball as it
leaves the gun
Which one is it? Help ASAP
Answer:
extreme heat, because no physical damage can demagnetize a magnet
Explanation:
Answer:
the 3rd one
Explanation:
In an effort to be the star of the half-time show, the majorette twirls a highly unusual baton made up of four mases fastened to the ends of light rods. Each rod is 1.0 m lone. Find the moment of inertia of the system about an axis perpendicular to the page and passing through the point where the rods cross.
Answer:
"0.25 kg-m²" is the appropriate answer.
Explanation:
The diagram of the question is missing. Find the attachment of the diagram below.
According to the diagram, the values are:
m₁ = 0.2
m₂ = 0.3
m₃ = 0.3
m₄ = 0.2
d₁ = d₂ = d₃ = d₄ = 0.5 m
As we know,
The moment of inertia is:
⇒ [tex]I=\Sigma M_id_i^2[/tex]
then,
⇒ [tex]I=m_1d_1^2+m_2d_2^2+m_3d_3^2+m_4d_4^2[/tex]
⇒ [tex]=d^2(m_1+m_2+m_3+m_4)[/tex]
On substituting the values, we get
⇒ [tex]=0.5^2\times (0.2+0.3+0.3+0.2)[/tex]
⇒ [tex]=0.25\times 1[/tex]
⇒ [tex]=0.25 \ Kg-m^2[/tex]
A cat dozes on a stationary merry-go-round, at a radius of 7.0 m from the center of the ride. The operator turns on the ride and brings it up to its proper turning rate of one complete rotation every 6.9 s. What is the least coefficient of static friction between the cat and the merry-go-round that will allow the cat to stay in place, without sliding
Answer:
0.6
Explanation:
Given that :
Radius, R = 7m
Period, T = 6.9s
The Coefficient of static friction, μs can be obtained using the relation :
μs = v² / 2gR
Recall, v = 2πR/T
μs becomes ;
μs = (2πR/T)² / 2gR
μs = (4π²R² / T²) ÷ 2gR
μs = (4π²R² / T²) * 1/ 2gR
μs = 4π²R / T²g
μs = 4π²*7 / 6.9^2 * 9.8
μs = 28π² / 466.578
μs = 276.34892 / 466.578
μs = 0.5922887
μs = 0.6
plz help me with my career!!!
part one...
Answer:
#1 Yes
Explanation: #1: The rest of them are used mainley by farmers, and crops are used by common citizens in the world.
Question 1: Crops.
Question 2: Diagnostic Services.
Question 3: A cable company needs to lay new fiber optic cable to reach its customers across a large lake.
Question 4: A bachelor's degree in energy research.
Question 5: Environmental Resources.
If any of these answers are incorrect, please tell me, so I can fix my mistake. Thank you.
A square wave has amplitude 0 V for the low voltage and 4 V for the high voltage. Calculate the average voltage by integrating over one period of the waveform. Hint: the equation for a square wave will be a piecewise function and it will be convenient to start the integration where the voltage changes; for example in this problem we could define that during the first half of the period the voltage is 0 V and for the second half of the period the voltage is 4 V
Answer:
V_{average} = [tex]\frac{1}{2} V_o[/tex] , V_{average} = 2 V
Explanation:
he average or effective voltage of a wave is the value of the wave in a period
V_average = ∫ V dt
in this case the given volage is a square wave that can be described by the function
V (t) = [tex]\left \{ {{V=V_o \ \ \ t< \tau /2} \atop {V=0 \ \ \ \ t> \tau /2 } } \right.[/tex]
to substitute in the equation let us separate the into two pairs
V_average = [tex]\int\limits^{1/2}_0 {V_o} \, dt + \int\limits^1_{1/2} {0} \, dt[/tex]
V_average = [tex]V_o \ \int\limits^{1/2}_0 {} \, dt[/tex]
V_{average} = [tex]\frac{1}{2} V_o[/tex]
we evaluate V₀ = 4 V
V_{average} = 4 / 2)
V_{average} = 2 V
Fat Albert (the TV show character) runs up the stairs on Monday. On Tuesday, he walks up the same set of stairs. Which day did he do more work?
Answer:
Tuesday bc instead of running he/she was walking bc he/she might not have as much energy
Explanation:
The Sun is divided into three regions.
True оr False?
Answer:
false I think
Explanation:
hope that help
so it's not divided in 3 regions
A typical laboratory centrifuge rotates at 4000 rpm. Testtubes have to be placed into a centrifuge very carefully because ofthe very large accelerations.
Part A) What is the acceleration at the end of a test tubethat is 10 cm from the axis of rotation?
Part B) For comparison, what is the magnitude of theacceleration a test tube would experience if dropped from a heightof 1.0 m and stopped in a 1.0-ms-long encounter with a hardfloor?
Answer:
A) a_c = 1.75 10⁴ m / s², B) a = 4.43 10³ m / s²
Explanation:
Part A) The relation of the test tube is centripetal
a_c = v² / r
the angular and linear variables are related
v = w r
we substitute
a_c = w² r
let's reduce the magnitudes to the SI system
w = 4000 rpm (2pi rad / 1 rev) (1 min / 60s) = 418.88 rad / s
r = 1 cm (1 m / 100 cm) = 0.10 m
let's calculate
a_c = 418.88² 0.1
a_c = 1.75 10⁴ m / s²
part B) for this part let's use kinematics relations, let's start looking for the velocity just when we hit the floor
as part of rest the initial velocity is zero and on the floor the height is zero
v² = v₀² - 2g (y- y₀)
v² = 0 - 2 9.8 (0 + 1)
v =√19.6
v = -4.427 m / s
now let's look for the applied steel to stop the test tube
v_f = v + a t
0 = v + at
a = -v / t
a = 4.427 / 0.001
a = 4.43 10³ m / s²
Jim and Sally both do identical jobs. Jim works quickly while Sally works slowly. Which of the following is true?
A) Sally uses more energy.
B) Jim uses more energy.
C) Jim uses more power.
D) Sally uses more power.
Suppose you are standing in front of a flat mirror which is mounted to a vertical wall. For this problem you may suppose that your height is 1.70 m and your eyes are 12 cm below the top of your head. What is the smallest mirror that will still allow you to see the full length of your body
Answer:
The right approach is "0.85 m".
Explanation:
According to the question, the diagram will is provided below.
So that as per the diagram,
The values will be:
My height,
AO = 1.70 m
My eyes at,
AB = 12 cm
i.e.,
= 0.12 m
As we can see, the point of incidence lies between the feet as well as the eyes, then
BO = 1.58 m
Now,
⇒ [tex]O'D = \frac{1.58}{2}[/tex]
[tex]=0.79 \ m[/tex]
The point of incidence of the ray will be:
⇒ [tex]CO'=1.70-\frac{0.12}{2}[/tex]
[tex]=1.70-0.06[/tex]
[tex]=1.64 \ m[/tex]
Hence,
The smallest length of the mirror will be:
= [tex]CO'-O'D[/tex]
On substituting the values, we get
= [tex]1.64-0.79[/tex]
= [tex]0.85 \ m[/tex]
A basketball player jumps straight up for a ball. To do this, he lowers his body 0.310 m and then accelerates through this distance by forcefully straightening his legs. This player leaves the floor with a vertical velocity sufficient to carry him 0.940 m above the floor. (a) Calculate his velocity (in m/s) when he leaves the floor. m/s (b) Calculate his acceleration (in m/s2) while he is straightening his legs. He goes from zero to the velocity found in part (a) in a distance of 0.310 m. m/s2 (c) Calculate the force (in N) he exerts on the floor to do this, given that his mass is 106 kg. N
Answer:A)u =4.295m/s , B)a = 29.746m/s² C) F=3,153N
Explanation:
Using the kinematic expression
v² = u² - 2as
where
u = initial velocity
v = final velocity
s = distance
g = acceleration due to gravity .
Given that he reaches a height of 0.940 m above the floor,
the final velocity = 0
Here, acceleration due to gravity is acting in opposite the initial direction of motion. So, a=-9.81 m/s.
v² = u² + 2as
0² - u² = 2 (- 9.81) × 0.940
- u² = 2 × - 9.81 × 0.920
- u² = -18.4428
cancelling the minus in both sides , we have that
u² = 18.4428
u = √18.4428
u =4.295m/s
(b) His acceleration (in m/s2) while he is straightening his legs. He goes from zero to the velocity found in part (a) in a distance of 0.310 m. m/s2
Using v² = u² + 2as
where u = initial speed of basketball player before lengthening = 0 m/s,
v = final speed of basketball player after lengthening = 4.295m/s,
a = acceleration while straightening his legs
s = distance moved during lengthening = 0.310m
v² = u² + 2as
a = (v² - u²)/2s
a = (4.29m/s)² - (0 m/s)²)/(2 × 0.310m)
a = (18.4428 m²/s² - 0 m²/s²)/(0.62 m)
a = (18.4428 m²/s²/(0.62 m)
a = 29.746m/s²
c) The force (in N) he exerts on the floor to do this, given that his mass is 106 kg. N
Force= mass x acceleration.
F = 106 kg X 29.746m/s²
F = 3,153.076 rounded to 3,153N
Attempt 2 You have been called to testify as an expert witness in a trial involving a head-on collision. Car A weighs 15151515 lb and was traveling eastward. Car B weighs 11251125 lb and was traveling westward at 42.042.0 mph. The cars locked bumpers and slid eastward with their wheels locked for 17.517.5 ft before stopping. You have measured the coefficient of kinetic friction between the tires and the pavement to be 0.7500.750 . How fast (in miles per hour) was car A traveling just before the collision
Answer:
v = 28.98 ft / s
Explanation:
For this problem we must solve it in parts, let's start by looking for the speed of the two cars after the collision
In the exercise they indicate the weight of each car
Wₐ = 1500 lb
W_b = 1125 lb
Car B's velocity from v_b = 42.0 mph westward, car A travels east
let's find the mass of the vehicles
W = mg
m = W / g
mₐ = Wₐ / g
m_b = W_b / g
mₐ = 1500/32 = 46.875 slug
m_b = 125/32 = 35,156 slug
Let's reduce to the english system
v_b = 42.0 mph (5280 foot / 1 mile) (1h / 3600s) = 61.6 ft / s
We define a system formed by the two vehicles, so that the forces during the crash have been internal and the moment is preserved
we assume the direction to the east (right) positive
initial instant. Before the crash
p₀ = mₐ v₀ₐ - m_b v_{ob}
final instant. Right after the crash
p_f = (mₐ + m_b) v
the moment is preserved
p₀ = p_f
mₐ v₀ₐ - m_b v_{ob} = (mₐ + m_b) v
v = [tex]\frac{ m_a \ v_{oa} - m_b \ v_{ob} }{ m_a +m_b}[/tex]
we substitute the values
v = [tex]\frac{ 46.875}{82.03} \ v_{oa} - \frac{35.156}{82.03} \ 61.6[/tex]
v = 0.559 v₀ₐ - 26.40 (1)
Now as the two vehicles united we can use the relationship between work and kinetic energy
the total mass is
M = mₐ + m_b
M = 46,875 + 35,156 = 82,031 slug
starting point. Jsto after the crash
K₀ = ½ M v²
final point. When they stop
K_f = 0
The work is
W = - fr x
the negative sign is because the friction forces are always opposite to the displacement
Let's write Newton's second law
Axis y
N-W = 0
N = W
the friction force has the expression
fr = μ N
we substitute
-μ W x = Kf - Ko
-μ W x = 0 - ½ (W / g) v²
v² = 2 μ g x
v = [tex]\sqrt{ 2 \ 0.750 \ 32 \ 17.5}[/tex]Ra (2 0.750 32 17.5
v = 28.98 ft / s
In a magnetized object, most of the domains point
a. in the same direction.
b. in an east-west direction.
c. in different directions.
d. perpendicular to one another.