A car is driving 12m/sec, has to stop suddenly because a pedestrian dashes out in front of the car. If the coefficient of kinetic friction between the tires and parking lot is ∪=60
what is the time, after the breaks are applied, before the car comes to a stop? Sketch the velocity time graph for the car's motion from the instant the breaks are applied until the car comes to a stop.
Answers
Answer:
Approximately [tex]2\; \rm s[/tex], assuming that the floor of this parking lot is level, [tex]\mu_{\rm k} = 0.60[/tex], and [tex]g = 9.81\; \rm m\cdot s^{-2}[/tex].
Explanation:
Let [tex]m[/tex] denote the mass of this vehicle. Weight of this vehicle: [tex]m\, g[/tex].
If the floor of this parking lot is level, the normal force on this vehicle would be equal to its weight: [tex]N = m \, g[/tex].
Given that [tex]\mu_{\rm k}[/tex], the kinetic friction between this vehicle and the ground would be consistently [tex]\mu_{\rm k} \, N = \mu_{\rm k} \, m \, g[/tex] until the vehicle comes to a stop.
Assuming that all forces on this vehicle other than friction are balanced. The net force of this vehicle during braking would be [tex](-\mu_{\rm k} \, m \, g)[/tex] (negative because this force is opposite to the direction of the motion.)
By Newton's second law of motion, the acceleration of this vehicle would be:
[tex]\begin{aligned}a &= \frac{F_\text{net}}{m} \\ &= \frac{-\mu_{\rm k} \, m \, g}{m} \\ &= -\mu_{\rm k}\, g \\ &= -0.60 \times 9.81\; \rm m\cdot s^{-2} \\ &= -5.886\; \rm m\cdot s^{-2}\end{aligned}[/tex].
In other words, braking would reduce the velocity of this vehicle by a constant [tex]5.886\; \rm m\cdot s^{-1}[/tex] every second until the vehicle comes to a stop. Calculate the time it would take to reduce the velocity of this vehicle from [tex]v_{0} = 12\; \rm m\cdot s^{-1}[/tex] to [tex]v_{1} = 0\; \rm m\cdot s^{-1}[/tex]:
[tex]\begin{aligned}t &= \frac{v_{1} - v_{0}}{a} \\ &= \frac{0\; \rm m\cdot s^{-1} - 12\; \rm m\cdot s^{-1}}{-5.886\; \rm m \cdot s^{-2}} \\ &\approx 2.0\; \rm s \end{aligned}[/tex].
Acceleration is the slope of the velocity-time graph. Since the acceleration here is constant, the velocity-time graph of this vehicle would be a line with a negative slope.
Related Questions
How long will it take a car, starting from rest, accelerating at 2 meters per second square to travel the same distance that another car traveling at a constant rate of 20m/s will travel?
Answers
20 seconds
Explanation:
Let [tex]x_a[/tex] be the distance traveled by the accelerating car and [tex]x_c[/tex] be the distance traveled by the car moving with a constant velocity. When they cover the same distance, we can write
[tex]x_a = x_c \Rightarrow v_{0a}t + \frac{1}{2}at^2 = v_ct[/tex]
where [tex]v_c[/tex] is the velocity of car moving at a constant rate and a is the acceleration of the accelerating car. Since the accelerating car started from rest, then [tex]v_{0a}[/tex] is zero so our equation above simplifies to
[tex]\frac{1}{2}at^2 = v_ct[/tex]
Note that the variable t cancels out so solving for t, we get
[tex]\frac{1}{2}at = v_c \Rightarrow t = \dfrac{2v_c}{a}[/tex]
Plugging in the given values,
[tex]t = \dfrac{2(20\:\text{m/s})}{2\:\text{m/s}^2} = 20\:\text{s}[/tex]
What is the average SPEED/VELOCITY of a car that traveled 1 complete lap around an oval track that’s 5000m long in 1000s
Answers
Answer:
5 m/s
Explanation:
5000/1000=5 m/s
:))
A ball is thrown up into the air. When it gets to the very top,
what kind of energy does it have?
Answers
At the highest attitude, the velocity of the ball is 0 m/s, so the kinetic energy is 0 as well.
Hence the answer is potential energy because it doesn't depend on velocity .
d what is
7 A rocket of mass 10000 kg uses 5.0kg of fuel and oxygen
to produce exhaust gases ejected at 5000 m/s. Calculate the
increase in its velocity
Answers
Answer:
Approximately [tex]2.5\; \rm m\cdot s^{-1}[/tex], assuming that no external force (e.g., gravitational pull) was acting on this rocket.
Explanation:
Assume that no external force is acting on this rocket. The system of the rocket and the fuel on the rocket would be isolated (an isolated system.) The momentum within this system would be conserved.
Let [tex]v_{0}\; \rm m\cdot s^{-1}[/tex] be the initial velocity of the rocket.
The velocity of the exhaust gas would be [tex](v_{0} - 5000)\; \rm m\cdot s^{-1}[/tex] since the gas is ejected away from the rocket.
Let [tex]\Delta v\; \rm m\cdot s^{-1}[/tex] denote the increase in the velocity of the rocket. The velocity of the rocket after ejecting the gas would be [tex](v + \Delta v)\; \rm m\cdot s^{-1}[/tex].
The momentum [tex]p[/tex] of an object of velocity [tex]v[/tex] and mass [tex]m[/tex] is [tex]p = m \cdot v[/tex].
The combined mass of the rocket and the fuel was [tex]10000\; \rm kg[/tex]. The initial momentum of this rocket-fuel system would be:
[tex]\begin{aligned}p_{0} &= m \cdot v\\ &= 10000\; {\rm kg} \times v_{0}\; {\rm m \cdot s^{-1}} \\ &= (10000\; v_{0})\; \rm {kg \cdot m\cdot s^{-1}}\end{aligned}[/tex].
The momentum of the [tex]5.0\; \rm kg[/tex] of fuel ejected at [tex](v_{0} - 5000)\; \rm m\cdot s^{-1}[/tex] would be:
[tex]\begin{aligned} & 5.0 \; {\rm kg} \times (v_{0} - 5000)\; {\rm m\cdot s^{-1}}\\ =\; & (5.0\, v_{0} - 25000)\; {\rm kg \cdot m \cdot s^{-1}}\end{aligned}[/tex].
After ejecting the [tex]5.0\; \rm kg[/tex] of the fuel, the mass of the rocket would be [tex]10000\; \rm kg - 5.0\; \rm kg = 9995\; \rm kg[/tex]. At a velocity of [tex](v + \Delta v)\; \rm m\cdot s^{-1}[/tex], the momentum of the rocket would be:
[tex]\begin{aligned} & 9995 \; {\rm kg} \times (v_{0} + \Delta v)\; {\rm m\cdot s^{-1}}\\ =\; & (9995\, v_{0} + 9995\, \Delta v)\; {\rm kg \cdot m \cdot s^{-1}}\end{aligned}[/tex].
Take the sum of these two quantities to find the momentum of the rocket-fuel system after the fuel was ejected:
[tex]\begin{aligned}p_{1} &= (5.0\, v_{0} - 25000)\; {\rm kg \cdot m\cdot s^{-1}\\ &\quad\quad + (9995\, v_{0} + 9995\, \Delta v)\; {\rm kg \cdot m \cdot s^{-1}} \\ &= (10000\, v_{0} + 9995\, \Delta v - 25000)\; {\rm kg \cdot m \cdot s^{-1}}\end{aligned}[/tex].
The momentum of the rocket-fuel system would be conserved. Thus [tex]p_{0} = p_{1}[/tex].
[tex](10000\, v_{0})\; {\rm kg \cdot m\cdot s^{-1}} = (10000\, v_{0} + 9995\, \Delta v - 25000)\; {\rm kg \cdot m \cdot s^{-1}}[/tex].
Solve this equation for [tex]\Delta v[/tex], the increase in the velocity of the rocket.
[tex]10000\, v_{0} = 10000\, v_{0} + 9995\, \Delta v - 25000[/tex].
[tex]9995\, \Delta v = 25000[/tex].
[tex]\begin{aligned}\Delta v &= \frac{25000}{9995} \approx 2.5\end{aligned}[/tex].
Thus, the velocity of the rocket would increase by approximately [tex]2.5\; \rm m\cdot s^{-1}[/tex] after ejecting the [tex]5.0\; \rm kg[/tex] of fuel.
What is the difference between the contagion theory and the convergence
theory?
O A. One deals with how people behave before a riot, and the other
deals with how people behave after a riot.
O B. One deals with adults with no power, and the other deals with
authority figures.
O C. One deals with how people are affected by a crowd, and the other
deals with how people actively drive a crowd's Behavior.
O D. One deals with people from democratic governments, and the
other deals with people from authoritarian governments.
Answers
Answer: Contagion theory states that crowds cause people to act in a certain way; convergence theory says the opposite, claiming that people who wish to act in a certain way come together to form crowds.
Explanation: Its C
When does your body conduct current more readily?
when it is hot
when it is dry
when it is cold
when it is wet
Answers
Answer:
When you are wet or you are sweating current passes easily.
Explanation:
wetness increases conductivity. therefore 'when it is wet'.
Which is a similar theme in both "The Stag at the Pool" and "Hans in Luck"? O A. The things we think are valuable sometimes turn out not to be valuable after all. 0 B. It is important to know whom we can trust and whom we cannot O C. By working hard, we will end up with possessions that will make us feel successful. 0 D. The best things come in small packages.
Answers
A similar theme in both "The Stag at the Pool" and "Hans in Luck" is A. The things we think are valuable sometimes turn out not to be valuable after all.
In "The stag at the pool", a thirsty stag went to the pool to drink. As he bent over, he admired his antlers but despised his legs. He saw a lion and ran but his antlers got stuck in a tree and he was caught by the lion.
The theme in "Hans in Luck" shows that one doesn't need possessions to be happy. The character in the story had several possessions but was still unhappy. Both themes showed that the things we think are valuable sometimes turn out not to be valuable after all.
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What state of matter is jelly?
Answers
Answer:
Hey mate.....
Explanation:
This is ur answer.....
SolidsJelly is a colloid where colloidal particles are solids which are dispersed in the liquid. Jelly is a fluid which can not be considered as a particular one kind of state. It is in the category of 'gel' which is a colloidal form.
Hope it helps!
Brainliest pls!
Follow me! ;)
An above ground swimming pool of 30 ft diameter and 5 ft depth is to be filled from a garden hose (smooth interior) of length 100 ft and diameter 5/8 inch. If the pressure at the faucet to which the hose is attached remains at 55 psi, how long will it take to fill the pool
Answers
This question involves the concepts of dynamic pressure, volume flow rate, and flow speed.
It will take "5.1 hours" to fill the pool.
First, we will use the formula for the dynamic pressure to find out the flow speed of water:
[tex]P=\frac{1}{2}\rho v^2\\\\v=\sqrt{\frac{2P}{\rho}}[/tex]
where,
v = flow speed = ?
P = Dynamic Pressure = 55 psi[tex](\frac{6894.76\ Pa}{1\ psi})[/tex] = 379212 Pa
[tex]\rho[/tex] = density of water = 1000 kg/m³
Therefore,
[tex]v=\sqrt{\frac{2(379212\ Pa)}{1000\ kg/m^3}}[/tex]
v = 27.54 m/s
Now, we will use the formula for volume flow rate of water coming from the hose to find out the time taken by the pool to be filled:
[tex]\frac{V}{t} = Av\\\\t =\frac{V}{Av}[/tex]
where,
t = time to fill the pool = ?
A = Area of the mouth of hose = [tex]\frac{\pi (0.015875\ m)^2}{4}[/tex] = 1.98 x 10⁻⁴ m²
V = Volume of the pool = (Area of pool)(depth of pool) = A(1.524 m)
V = [tex][\frac{\pi (9.144\ m)^2}{4}][1.524\ m][/tex] = 100.1 m³
Therefore,
[tex]t = \frac{(100.1\ m^3)}{(1.98\ x\ 10^{-4}\ m^2)(27.54\ m/s)}\\\\[/tex]
t = 18353.5 s = 305.9 min = 5.1 hours
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How would you best define the word drug?
A: Something that makes you tired
B: Something that can kill you
C: Something that effects your body and mind
D: Stored for energy
someone help
Answers
Answer:
C
Explanation:
Definition of drug: a medicine or other substance which has a physiological effect when ingested or otherwise introduced into the body
Two airplanes taxi as they approach the terminal. Plane 1 taxies with a speed of 13 m/s due north. Plane 2 taxies with a speed of 8.5 m/s in a direction 20 ∘ north of west.
Part A
What is the magnitude of the velocity of plane 1 relative to plane 2?
Part B
What is the direction of the velocity of plane 1 relative to plane 2?
Part C
What are the magnitude of the velocity of plane 2 relative to plane 1?
Answers
Answer:
Explanation:
Plane 2 is moving north at
8.5sin20 = 2.9 m/s
Plane 2 is moving west at
8.5cos20 = 8.0 m/s
Part A
v = √((13 - 2.9)² + 8.0²) = 12.876... 13 m/s
Part B
θ = arctan((13 - 2.9) / 8.0) = 51.617... 52° N of E
Part C
13 m/s 52° S of W
relative velocity magnitude is independent of reference frame
Five ramps lead from the ground to the second floor of a workshop, as sketched below. All five ramps have the same height; ramps B, C, D and E have the same length; ramp A is longer than the other four. You need to push a heavy cart up to the second floor and you may choose any one of the five ramps.Assuming no frictional forces on the cart, which ramp would require you to do the least work?
Answers
The mechanical advantage of ramp A is greater than others and it will require the least force to move the load to greater distance.
Let the height of the ramp = hLet the length of ramp B, C, D and E = LLet the length of the ramp A = 2LThe mechanical advantage of the ramp is calculated as follows;
[tex]M.A = \frac{L}{h}[/tex]
The mechanical advantage of the ramp B, C, D and E is calculated as;
[tex]M.A = \frac{L}{h} \\\\[/tex]
The mechanical advantage of the ramp A is calculated as follows;
[tex]M.A = \frac{2L}{h} \\\\M.A = 2(\frac{L}{h} )[/tex]
Since the length of the ramp A is greater than other ramps, the mechanical advantage will be greater and it will require the least force to move the load to greater distance.
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Describe the concept of energy quanta of EM radiation which was explained by Planck.
Answers
Answer:
Planck postulated that the energy of light is proportional to the frequency, and the constant that relates them is known as Planck's constant (h). His work led to Albert Einstein determining that light exists in discrete quanta of energy, or photons.
Explanation:
Answer:
Energy does not occur in continuous amounts but in discrete amounts described by:
E = N h ∨ where N is the number of quanta (energy units), ∨ the frequency of the energy, and h Planck's constant (6.63E-34 J-sec)
This is for Lipor only.
Answers
Answer:
im here\
Explanation:
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1- a car speeds up to get onto the freeway. it goes from 21 m/s to 39 m/s in 4.1 seconds. How far did it travel??
2- a boulder fell off a cliff and fell for 4.1 seconds. How tall was the cliff?
Answers
Answer:
Explanation:
1) average velocity is
v = (21 + 39)/2 = 30m m/s
d = vt 30(4.1) = 123 = 120 m
2) d = ½gt²
d = ½(9.8)(4.1²)
d = 82.369 = 82 m
when rounding to the two significant digits of the question numerals.
What is the cause of plate tectonics on Earth?
The magnetic field
Tides in the ocean
Convection in the mantle
Volcanic eruptions
Answers
Answer:
im pretty sure the answer is C
What are the 7 different states of matter in Chemistry?How many states of matter are there?
Answers
Answer:
The 7 states of matter are solid, loquid, gas, fermionoc condensate, quark gluton plasm, bose einetein condensate amd ionised plasm but its usually only 3 they teach you
Answer:
7
Explanation:
solid, liquid,gas,fermionoc condensate,quark glutton plasm,bose einetein condensate amd ionised plasm.
help :”)
a skydiver jumps out of a plane and falls for 45 seconds before deploying his parachute. how far did he fall?
Answers
Answer:
200 feet
Explanation:
A race car, starting from rest, travels around a circular turn of radius 22.5 m. At a certain instant the car is still speeding up, and its angular speed is 0.541 rad/s. At this time, the car’s total acceleration vector (centripetal plus tangential) makes an angle of 39.0 with respect to the car’s velocity. What is the magnitude of the car’s total acceleration
Answers
Answer:
Explanation:
The answer:
https://www.chegg.com/homework-help/questions-and-answers/race-car-starting-rest-travels-around-circular-turn-radius-247-m-certain-instant-car-still-q402991
Total acceleration of car is 148.31 m/s².
What is centripetal acceleration?Centripetal acceleration is a characteristic of an object's motion along a circular path. Centripetal acceleration applies to any item travelling in a circle with an acceleration vector pointing in the direction of the circle's center.
Given parameters:
Radius of the circular path: r = 22.5 m.
Angular speed: ω = 0.541 rad/s.
So, centripetal acceleration; α = ω²r = (0.541)² × 22.5 m/s² = 6.58 m/s².
Tangential acceleration: [tex]\alpha_t[/tex] = αr = 6.58 × 22.5 = 148.16 m/s².
Hence, total acceleration = √(α² + [tex]\alpha_t[/tex]²) = √(6.58² +148.16²) = 148.31 m/s².
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Question 3. A wire 25.0cm long lies along the z-axis and carries a current of 9.00A in the +z-direction. The a magnetic field is uniform and has components Bx = -0.242T, By= -0.985, and B2=-0.336. a. Find the components of the magnetic force on the wire? b. What is the magnitude of the net magnetic force on the wire?
Answers
a.
The components of the force are Fx = 2.2163 N, Fy = -0.5445 N and Fz = 0 N
The force on a current carrying conductor in a magnetic field is given by F = iL × B where i = current = 9.00 A, L = 25.0 cmk = 0.25 mk (since the conductor is along the z-direction). B = magnetic field. Since B has component Bx = -0.242T, By= -0.985, and Bz = -0.336, B = -0.242i + (-0.985j) + (-0.336)k = -0.242i - 0.985j - 0.336)k.
So, F = iL × B
F = 9.00 A{(0.25 m)k × [-0.242Ti + (-0.985Tj) + (-0.336T)k]T}
F = 9.00 A{(0.25 m)k × (-0.242T)i + (0.25 m)k × (-0.985Tj) + (0.25 m)k × (-0.336T)k]}
F = 9.00 A{-0.0605mT)k × i + (-0.24625 mT)k × j + (-0.084 m)k × k]}
F = 9.00 A{-0.0605mT)j + (-0.24625 mT) × -i + (-0.084 mT) × 0]}
F = 9.00 A{-0.0605mT)j + (0.24625 mT)i + 0 mT]}
F = -0.5445 AmT)j + (2.21625 AmT)i + 0 AmT]}
F = -0.5445j + 2.21625i + 0 k
F = (2.2163i - 0.5445j + 0 k) N
So, the components of the force are Fx = 2.2163 N, Fy = -0.5445 N and Fz = 0 N
b.
The magnitude of the net force on the wire is 2.282 N
The net force F = √(Fx² + Fy² + Fz²)
F = √[(2.2163 N)² + (-0.5445 N)² + (0 N)²)
F = √[(4.912 N)² + 0.2964 N)² + (0 N)²)
F = √[5.2084 N)²
F = 2.2822 N
F ≅ 2.282 N
So, the magnitude of the net force on the wire is 2.282 N
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How do organisms use communication to survive?
Answers
Answer: Im not entirly sure but I think It's D all the above. I think all but B because I never really heard of that but if you look in our history I think that happen im not sure I would wait untill you know that somone knows for sure.
Explanation:
Find the first three harmonics of a string of linear mass density 2.00 g/m and length 0.600 m when it is subjected to tension of 50.0 N.
Answers
Hi there!
We can use the following equation to find the frequency of each harmonic:
[tex]f_n = \frac{n}{2L} \sqrt{\frac{T}{\lambda}}[/tex]
n = nth harmonic
L = length of string (m)
T = Tension of string (N)
λ = linear density (kg/m)
Begin by converting the linear mass density to kg:
2.00g /m · 1 kg / 1000g = 0.002 kg/m
Now, we can use the equation to find the first three harmonics.
First harmonic:
[tex]f_1 = \frac{1}{2(0.6)} \sqrt{\frac{50}{0.002}} = \boxed{131.76 Hz}[/tex]
Second harmonic:
[tex]f_2 = \frac{2}{2(0.6)} \sqrt{\frac{50}{0.002}} = \boxed{263.52Hz}[/tex]
Third harmonic:
[tex]f_3 = \frac{3}{2(0.6)} \sqrt{\frac{50}{0.002}} = \boxed{395.28Hz}[/tex]
Why is the sky blue and why do we get a sunset
Answers
Answer:
Small particles of dust and pollution in the air can contribute to (and sometimes even enhance) these colors, but the primary cause of a blue sky and orange/red sunsets or sunrises is scattering by the gas molecules that make up our atmosphere. Large particles of pollution or dust scatter light in a way that changes much less for different colors.
Explanation:
Does it appear that true average HAZ depth is larger for the high current condition than for the nonhigh current condition
Answers
Answer:
The data suggest that the true mean HAZ depth is larger when the current setting is higher.
what two things make up an ionic bond?
Answers
What are cyclotrons and how are they used?
Answers
The second hand on a clock is 3.00 cm long. What is the speed of the outermost tip of that second hand
Answers
In 60 minutes or 3600 seconds, the tip of the minute hand traverses the circumference of a circle with radius 3.00 cm, so it moves with a tangential speed of
(3.00 cm)/(3600 s) ≈ 0.00083 cm/s = 8.3 μm/s
If a battery causes a wire to carry a current of 4 Amps how many coulombs of charge flow past any point in the wire in 3 seconds
Answers
[tex]▪▪▪▪▪▪▪▪▪▪▪▪▪ {\huge\mathfrak{Answer}}▪▪▪▪▪▪▪▪▪▪▪▪▪▪[/tex]
According to above question ~
Current (I) = 4 AmperesTime (t) = 3 seconds Charge (q) = ?Let's find the charge (q) by using formula ~
[tex]I = \dfrac{q}{t} [/tex][tex]4 = \dfrac{q}{3} [/tex][tex]q = 4 \times 3[/tex][tex]q = 12 \: \: coulombs[/tex]Hence, 12 coulombs of charge flow past any point in the wire in 3 seconds
Look at the simple machine shown below to determine the mechanical advantage
Answers
Answer:
A
Explanation:
tell types of instruments
Answers
Answer:
Instrument Use
Accelerometer Measures acceleration
Altimeter Measures altitude of an aircraft
Ammeter Measures electric current in ampere
Anemometer Measures wind speed