A 20kg rock is sliding on a rough, horizontal surface at 8 m/s and eventually stops due to friction. the coefficient of kinetic friction between the rock and the surface is 0.200. what average power is produced by friction as the rock stops?
Answer:
156watts
Explanation:
M = 20
U = 0.200
Vo = 8.0
We are to get p
P = w/t
W = 1/2(vf²-Vo²)
The final velocity is 0
W =-1/2*20*8²
= -640J
Acceleration = -ug
= -0.200*9.8
= -1.96m/s^-2
We are to get t
t = 8/1.96
= 4.1s
P = w/t
= 640/4.1
= 156 watts
156watts is the average power that is produced by friction as the rock stops.
Help!!! Need answer ASAP.
Answer:
a = 0.5 [m/s²]
Explanation:
To solve this problem we must use Newton's second law which tells us that the sum of forces is equal to the product of mass by acceleration.
ΣF = m*a
F = force = 200 [N]
m = mass = 400 [kg]
a = acceleration [m/s²]
Now replacing:
200 = 400*a
a = 0.5 [m/s²]
A 67.6-kg boy is surfing and catches a wave which gives him an initial speed of 1.56 m/s. He then drops through a height of 1.65 m, and ends with a speed of 8.30 m/s. How much nonconservative work was done on the boy?
Answer:
The nonconservative work was done on the boy is 1154.87 J.
Explanation:
Given;
mass of the boy, m = 67.6 kg
initial speed of the boy, u = 1.56 m/s
height of fall, h = 1.65 m
final speed of the boy, v = 8.30 m/s
The initial energy of the boy is given by;
E₁ = K.E₁ + P.E₁
E₁ = ¹/₂mu² + mgh
E₁ = ¹/₂(67.6)(1.56)² + (67.6 x 9.8 x 1.65)
E₁ = 82.134 + 1091.475
E₁ = 1,173.61 J
The final energy of the boy is given by;
E₂ = K.E₂
E₂ = ¹/₂mv²
E₂ = ¹/₂(67.6)(8.3)²
E₂ = 2,328.482 J
The nonconservative work was done on the boy is given by;
W = E₂- E₁
W = 2,328.482 J - 1,173.61 J
W = 1154.87 J
Therefore, the nonconservative work was done on the boy is 1154.87 J.
How long does it take a vehicle to reach a velocity of 32 m/s if it accelerates from rest at a rate of 4.2 m/s^2? ANSWER ALL PLEASE!! Im dumb:(
What is the initial velocity of the vehicle?
What is the final velocity of the vehicle?
What is the acceleration of the vehicle?
Write the equation you will use to solve the problem.
How long does it take the vehicle to reach its final velocity?
0.13 seconds
18.1 seconds
7.62 seconds
134.4 seconds
Answer: Givens
a = 4.4 m/s^2 This is an acceleration and is positive.
vi = 10.2 m/s
t = 4.2 seconds
vf = ????? The cruising speed in this case is vf.
Formula
a = (vf - vi)/t Notice the 3 givens and what you seek determine the formula
Solve
4.4 m/s^2 = (vf - 10.2)/4.2 Multiply both sides by 4.2
4.4 * 4.2 = vf - 10.2
18.48 = vf - 10.2 Add 10.2 to both sides
18.48 + 10.2 = vf 8.28 is the second best answer.
28.68 = vf This is your cruising speed.
C <<<< Answer
7.62 (2dp)
Explanation:
U = 0m/s
V = 32m/s
A = 4.2m/s^2
T = ?
[tex]a = \frac{v - u}{t}[/tex]
[tex]t = \frac{v - u}{a} [/tex]
[tex]t = \frac{32 - 0}{4.2} [/tex]
[tex]t = \frac{32}{4.2} [/tex]
[tex]t = 7.62 \: (2dp)[/tex]
If you liked this answer, brainliest?
Determine the force of gravitational attraction between a 92 kg student and a 550 g slice of pizza that are 25 cm apart
Answer:
F = 5.4 x 10⁻⁸ N
Explanation:
The gravitational force of attraction between two objects is given by Newton's Gravitational Law as follows:
F = Gm₁m₂/r²
where,
F = Gravitational Force = ?
G = Universal Gravitational Constant = 6.67 x 10⁻¹¹ N.m²/kg²
m₁ = mass of student = 92 kg
m₂ = mass of pizza slice = 550 g = 0.55 kg
r = distance between student and pizza slice = 25 cm = 0.25 m
Therefore,
F = (6.67 x 10⁻¹¹ N.m²/kg²)(92 kg)(0.55 kg)/(0.25 m)²
F = 5.4 x 10⁻⁸ N
A wire of radius 0.8 cm carries a current of 106 A that is uniformly distributed over its cross-sectional area. Find the magnetic field B at a distance of 0.07 cm from the center of the wire.
Answer:
The magnetic field is [tex]B = 2.319 *10^{-3} \ T[/tex]
Explanation:
From the question we are told that
The radius of the wire is [tex]r = 0.8 \ cm = 0.008 \ m[/tex]
The current is [tex]I = 106 \ A[/tex]
The position considered is d = 0.07 cm = 0.0007 m
Generally the magnetic field is mathematically represented as
[tex]B = \frac{\mu_o * I}{2\pi * \frac{r^2}{d} }[/tex]
Here [tex]\mu_o[/tex] is the permeability of free space with value [tex] 4\pi * 10^{-7} N/A^2[/tex]
So
[tex]B = \frac{ 4\pi * 10^{-7} * 106 }{2 * 3.142 * \frac{0.008^2}{0.0007} }[/tex]
=> [tex]B = 2.319 *10^{-3} \ T[/tex]
g A ping pong ball (thin shell sphere) rolls down an incline at 30° from rest. What is its acceleration
Answer:
Explanation:
According to newtons second law of motion;
F = ma .... 1
Also the force acting aong the inclines is expressed as;
F = mgsintheta
m is the mass of the object
a is the acceleration
theta is angle of inclination
Equate 1 and 2
ma = mg sin theta
a = gsin(theta)
a = 9.8sin30
a = 9.8(0.5)
a = 4.9m/s²
Hence the acceleration of the ping pong is 4.9m/s²
You can chew through very tough objects with your incisors because they exert a large force on the small area of a pointed tooth. What pressure in pascals can you create by exerting a force of 500 N with your tooth on an area of 1.00 mm?
Answer:
sry i need points
Explanation:
A displacement vector with a magnitude of 20. meters could have perpendicular components with magnitudes of A. 10. m and 10. m B. 12 m and 8.0 m 12 m and 16 m D. 16 m and 8.0 m
Answer:10.m and 10. M
Explanation:
A displacement vector with a magnitude of 20. m could have perpendicular components with magnitudes of C. 12 m and 16 m.
A displacement vector with a magnitude of 20. meters can be decomposed in 2 perpendicular components.
They would form a right triangle, in which the displacement vector would be the hypotenuse (a) and the components would be the legs (b, c).
Given the magnitude of the legs, we can calculate the magnitude of the hypotenuse using the Pythagorean theorem.
[tex]c = \sqrt{a^{2} + b^{2} }[/tex]
Let's use this formula to calculate the displacement vector for each pair of legs.
A. 10. m and 10. m[tex]c = \sqrt{a^{2} + b^{2} } = \sqrt{(10.m)^{2} + (10.m)^{2} }= 14.1m[/tex]
B. 12 m and 8.0 m[tex]c = \sqrt{a^{2} + b^{2} } = \sqrt{(12m)^{2} + (8.0m)^{2} }= 14.4m[/tex]
C. 12 m and 16 m[tex]c = \sqrt{a^{2} + b^{2} } = \sqrt{(12m)^{2} + (16m)^{2} }= 20m[/tex]
D. 16 m and 8.0 m[tex]c = \sqrt{a^{2} + b^{2} } = \sqrt{(16m)^{2} + (8.0m)^{2} }= 17.9m[/tex]
A displacement vector with a magnitude of 20. m could have perpendicular components with magnitudes of C. 12 m and 16 m.
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You discover a binary star system in which one member is a15MSun main-sequence star and the other star is a 10MSun giant. How do we believe that a star system such as this might have come to exist?
Answer:
Explanation:
The giant star must have at least once been the more massive star and then subsequently transferred some of its mass to its companion, the other star.
The two stars would be around the same age, so the more massive one would have turned into a giant first before the other one did or even had a chance to
When an aluminum bar is connected between a hot reservoir at 720 K and a cold reservoir at 358 K, 3.00 kJ of energy is transferred by heat from the hot reservoir to the cold reservoir. (a) In this irreversible process, calculate the change in entropy of the hot reservoir._______ J/K
(b) In this irreversible process, calculate the change in entropy of the cold reservoir.
_______ J/K
(c) In this irreversible process, calculate the change in entropy of the Universe, neglecting any change in entropy of the aluminum rod.
_______ J/K
(d) Mathematically, why did the result for the Universe in part (c) have to be positive?
Answer:
a. -4.166 J/K
b. 8.37 J/K
c. 4.21 J/K
d. entropy always increases.
Explanation:
Given :
Temperature at hot reservoir , [tex]$T_h$[/tex] = 720 K
Temperature at cold reservoir , [tex]$T_c$[/tex] = 358 K
Transfer of heat, dQ = 3.00 kJ = 3000 J
(a). In the hot reservoir, the change of entropy is given by:
[tex]$dS_h= -\frac{dQ}{t_h}$[/tex] (the negative sign shows the loss of heat)
[tex]$dS_h= -\frac{3000}{720}$[/tex]
= -4.166 J/K
(b) In the cold reservoir, the change of entropy is given by:
[tex]$dS_c= \frac{dQ}{t_c}$[/tex]
[tex]$dS_c= \frac{3000}{358}$[/tex]
= 8.37 J/K
(c). The entropy change in the universe is given by:
[tex]$dS=dS_h+dS_c$[/tex]
= -4.16+8.37
= 4.21 J/K
(d). According to the concept of entropy, the entropy of the universe is always increasing and never decreasing for an irreversible process. If the entropy of universe decreases, it violates the laws of thermodynamics. Hence, in part (c), the result have to be positive.
Which of these should you always do at the end of a calculation
Answer:
Reverse check the answer
Explanation:
I believe it is very important that once someone is done with any calculation, the person ought to go over the calculations again. And even, recheck the answer in inverted form.
This is so because while doing the calculations, we can possibly make errors that we won't notice until after submission. Knowing 2 * 3 = 6, but writing 2 * 3 = 5 in the course of calculations can happen to anybody. So therefore, cross checking and reverse checking is needed
The spring constant, k, for a 22cm spring is 50N/m. A force is used to stretch the spring and when it is measured again it is 32cm long. Work out the size of this force
Answer:
5N
Explanation:
Given parameters:
Original length = 22cm
Spring constant, K = 50N/m
New length = 32cm
Unknown
Force applied = ?
Solution:
The force applied on a spring can be derived using the expression below;
Force = KE
k is the spring constant
E is the extension
extension = new length - original length
extension = 32cm - 22cm = 10cm
convert the extension from cm to m;
100cm = 1m;
10cm will give 0.1m
So;
Force = 50N/m x 0.1m = 5N
A runaway train car that has a mass of 15,000 kg travels at a speed of 5.4 m/s down a track. Compute the time required for a force of 1500 N to bring it to rest.
(a) 0.019 s
(b) 54s
(c) 4.2Ã106s
(d) 2.4Ã10â7s
Answer:
54 s
Explanation:
Given that,
Mass of a car, m = 15000 kg
Initial speed, u = 5.4 m/s
Final speed, v = 0 (it comes to rest)
Force, F = 1500 N
We need to find time when it comes to rest. Let it is t. Net force is given by :
F = ma, a is acceleration of the car
[tex]F=\dfrac{m(v-u)}{t}\\\\t=\dfrac{m(v-u)}{F}\\\\t=\dfrac{15000\times (0-5.4)}{1500}\\\\t=54\ s[/tex]
So, it will take 54 seconds to come to rest.
The time required to bring the car to rest is 54 s and the right option is (b) 54 s.
To calculate the time required for the force to bring the car to rest, we use the formula below.
Formula:
F = m(v-u)/t............ Equation 1Where:
F = Force applied to the carm = mass of the carv = final velocity of the caru = initial velocity of the cart = time.Make t the subject of the equation
t = m(v-u)/F............. Equation 2From the question,
Given:
F = -1500 N (stopping force)m = 15000 kgv = 0 m/s (to rest)u = 5.4 m/sSubstitute these values into equation 2
t = [1500(0-5.4)]/-1500t = -81000/-1500t = 54 secondst ≈ 54 sHence, The time required to bring the car to rest is 54 s and the right option is (b) 54 s.
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Calculate the distance covered by a bus moving at a rate of 11.5km/h with a time of 2060seconds
Answer:
6.56km
Explanation:
Given parameters:
Speed = 11.5km/hr
Time = 2060s
Unknown:
Distance covered = ?
Solution:
Speed is distance divided by the time taken.
Speed = [tex]\frac{distance}{time}[/tex]
Distance = Speed x time
Let us convert the seconds to hours;
3600s = 1hr
2060s = [tex]\frac{2060}{3600}[/tex] = 0.57hr
Now
Distance = 11.5km/hr x 0.57hr = 6.56km
How do bones develop and grow?
Answer:
Explanation:
Bones grow in length at the epiphyseal plate by a process that is similar to endochondral ossification. The cartilage in the region of the epiphyseal plate next to the epiphysis continues to grow by mitosis. The chondrocytes, in the region next to the diaphysis, age and degenerate.
An experiment consists of throwing balls straight up with varying initial velocities. Which quantity will have the same value in all trials?a) initial momentum.
b) maximum height.
c) time of travel.
d) acceleration.
Answer:
the correct answer is D, acceleration of gravity
Explanation:
In a projectile launch problem it is described by the expressions
v = v₀ - g t
v² = v₀² - 2 g y
y = v₀ t - ½ g t²
By examining these equations we can see that acceleration is the magnitude that appears constant in all expressions.
This acceleration is the acceleration of gravity with a value of g = 9.8 m/s² and directed towards the center of the Earth
therefore the correct answer is D
Two manned satellites approach one another at a relative speed of 0.400 m/s, intending to dock. The first has a mass of 5.50 ✕ 103 kg, and the second a mass of 7.50 ✕ 103 kg. If the two satellites collide elastically rather than dock, what is their final relative velocity in meters per second?
Answer:
why do you think the senate changed the way it voted? What methods did the suf
why do you think the senate changed the way it voted? What methods did the suffragis
why do you think the senate changed the way it voted? What methods did the suffragists use to influence this change?
Two manned satellites approach one another at a relative speed of 0.400 m/s, intending to dock. The first has a mass of 5.50 ✕ 103 kg, and the second a mass of 7.50 ✕ 103 kg. If the two satellites collide elastically rather than dock, what is their final relative velocity in meters per second?
hi
lolTwo manned satellites approach one another at a relative speed of 0.400 m/s, intending to dock. The first has a mass of 5.50 ✕ 103 kg, and the second a mass of 7.50 ✕ 103 kg. If the two satellites collide elastically rather than dock, what is their final relative velocity in meters per second?ts use to influence this change?
Two manned satellites approach one another at a relative speed of 0.400 m/s, intending to dock. The first has a mass of 5.50 ✕ 103 kg, and the second a mass of 7.50 ✕ 103 kg. If the two satellites collide elastically rather than dock, what is their final relative velocity in meters per second?
hi
lolfragists use to influence this change?
Explanation:
Two manned satellites approach one another at a relative speed of 0.400 m/s, intending to dock. The first has a mass of 5.50 ✕ 103 kg, and the second a mass of 7.50 ✕ 103 kg. If the two satellites collide elastically rather than dock, what is their final relative velocity in meters per second?
hilol
The batter swings his bat 1.8 meters in 0.1 seconds. How fast is his bat speed in meters per second?
Answer:
18 m/s
Explanation:
1.8 meters / 0.1 seconds = 18 m/s
You use an electron microscope in which the matter wave associated with the electron beam has a wavelength of 0.0173 nm. What is the kinetic energy of an electron in the beam, expressed in electron volts?
Answer:
The kinetic energy of an electron in the beam is 5.04 keV.
Explanation:
We need to find the velocity of the electron by using the De Broglie wavelength:
[tex] \lambda = \frac{h}{mv} [/tex]
Where:
λ: is the wavelength = 0.0173 nm
v: is the velocity
m: is the electron's mass = 9.1x10⁻³¹ kg
h: is the Planck constant = 6.62x10⁻³⁴ J.s
[tex] v = \frac{h}{m\lambda} = \frac{6.62 \cdot 10^{-34} J.s}{9.1 \cdot 10^{-31} kg*0.0173 \cdot 10^{-9} m} = 4.21 \cdot 10^{7} m/s [/tex]
Now, we can find the kinetic energy:
[tex] E_{k} = \frac{1}{2}mv^{2} = \frac{1}{2}9.1 \cdot 10^{-31} kg*(4.21 \cdot 10^{7} m/s)^{2} = 8.06 \cdot 10^{-16} J*\frac{1 eV}{1.6 \cdot 10^{-19} J} = 5038 eV = 5.04 keV [/tex]
Therefore, the kinetic energy of an electron in the beam is 5.04 keV.
I hope it helps you!
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Question
An airplane flies eastward and always accelerates at a constant rate. At one position along its path, it has a velocity of
32.7 m/s. It then flies a further distance of 44500 m, and afterwards, its velocity is 50.3 m/s. Find the
airplane's acceleration
acceleration:
.016m/s2
Calculate how much time clapses while the airplane covers those 44500 m
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49 ENG
1:45 PM
9/17/2020
Answer:
Explanation:
initial velocity u = 32.7 m /s
final velocity v = 50.3 m /s
displacement s = 44500 m
acceleration a = ?
v² = u² + 2 a s
50.3² = 32.7² + 2 x a x 44500
2530.09 = 1069.29 + 89000a
a .016 m /s²
time taken t = ?
v = u + at
50.3 = 32.7 + .016 t
t = 1100 s
please help i will mark brainliest
what does a speedometer measure?
a. accerlation
b. velocity
c. speed
d. average speed.
Answer:
c. speed
Explanation:
Speedometer is a device used to measure the speed of a vehicle. I am pretty sure this is the correct option.
A 0.12-m-radius grinding wheel takes 5.5 s to speed up from 2.0 rad/s to 11.0 rad/s. What is the wheel's average angular acceleration?
Answer:
0.56rad/s²
Explanation:
Using the equation of motion
wf = wi + αt
wf is the final angular velocity
wi is the initial angular velocity
α is the angular acceleration
t is the time
Given
wf = 11.0rad/s
wi =2.0rad/s
t = 5.5secs
Substitute into the formula and get α
11.0 = 2.0+5α
11.0-2.0 = 5α
9.0 = 5α
α = 5/9.0
α ≈ 0.56rad/s²
Hence the wheel's average angular acceleration is 0.56rad/s²
The wheel's average angular acceleration is equal to 1.64 [tex]rad/s^2[/tex].
Given the following data:
Radius = 0.12 meterTime = 5.5 secondsInitial angular velocity = 2.0 rad/sFinal angular velocity = 11.0 rad/sTo determine the wheel's average angular acceleration, we would apply the first equation of kinematics:
Mathematically, the angular acceleration of an object is given by the formula:
[tex]\alpha = \frac{\omega_f - \omega_i}{t}[/tex]
Where:
[tex]\omega_i[/tex] is the initial angular velocity.[tex]\omega_f[/tex] is the final angular velocity.t is the time.Substituting the given parameters into the formula, we have;
[tex]\alpha =\frac{11.0\;-\;2.0}{5.5} \\\\\alpha =\frac{9.0}{5.5}[/tex]
Angular acceleration = 1.64 [tex]rad/s^2[/tex]
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I’m so confused someone help
Which theory explains why gravity between two objects changes when the distance between them changes?
Einstein's theory because he suggested that the more distance there is between objects, the more space-time
curves and the greater the strength of gravity is.
Einstein's theory because he suggested that the more distance there is between objects, the more space-time
curves and the weaker the strength of gravity is.
Newton's theory because he suggested that the greater the distance between objects, the greater the pull of gravity.
Newton's theory because he suggested that the greater the distance between objects, the weaker the pull of gravity.
Answer:
Newton's theory because he suggested that the greater the distance between objects, the weaker the pull of gravity.
Answer: The answer is Newton’s theory because he suggested that the greater the distance between objects, the weaker the pull of gravity
Explanation: Just took the test i hope this help you enjoy :D
An unbalanced 16.0N force is applied to a2.0kg mass. What is the acceleration of the mass?
Answer:
Yuh
Explanation:
Which possible component of initial energy is caused by molecular motion within a material?
Answer: thermal energy
Answer:
Thermal energy
Explanation:
The internal energy of a system is widely known as thermal energy. Now, thermal energy is also called heat energy and it is an internal energy of a component which is produced when an increase in temperature causes atoms and molecules within the component to move faster and start colliding with one other.
Therefore, the more heat the is applied to the component, the hotter the substance and the more its particles move which in turn leads to a higher thermal energy.
A flat loop of wire consisting of a single turn of cross-sectional area 7.10 cm2 is perpendicular to a magnetic field that increases uniformly in magnitude from 0.500 T to 2.10 T in 1.07 s. What is the resulting induced current if the loop has a resistance of 1.60?
Answer:
The induced current is [tex]I = 0.00066 \ A[/tex]
Explanation:
From the question we are told that
The area is [tex]A = 7.10 \ cm^2 = 7.10 *10^{-4} \ m^2[/tex]
The initial magnetic field is [tex]B_i = 0.500 \ T[/tex]
The magnetic field after t =1.07 s is [tex]B_f = 2.10 \ T[/tex]
The resistance of the loop is [tex]R = 1.60 \ \Omega[/tex]
Generally the electromagnetic field induced is mathematically represented as
[tex]\epsilon = NA * \frac{B_f - B_i}{t}[/tex]
Where N is the number of turns which is 1 in the case of this question since there is only one loop
So
[tex]\epsilon = 1 * 7.10*10^{-4}* \frac{2.10 - 0.500}{1.07 }[/tex]
=> [tex]\epsilon = 0.00106 \ V[/tex]
Generally the value of the current is mathematically represented as
[tex]I = \frac{\epsilon}{R}[/tex]
[tex]I = \frac{0.00106}{1.60}[/tex]
[tex]I = 0.00066 \ A[/tex]
22. What happens to the volume of a 1 kg of water when it is heated from 4oC to 6oC? A. Increases B. Decreases C. Stays the same
Answer:
a
Explanation:
..................
An electric motor spins at a constant 2695.0 rpm. If the rotor radius is 7.165 cm, what is the linear acceleration of the edge of the rotor?A) 5707 m/s^2 B) 281.6 m/s^2 C) 28.20 m/s^2 D) 572,400 m/s^2
Answer:
5707 m/s^2
Explanation: