A car traveled 1,215 km West from El Paso to Dallas in 13.5 hours. What was its velocity? A: 90 m/s west B. 90km/h C. .09km/h West D. 90km/h West
Answer:
B. 90km/hr
Explanation:
The formula for finding velocity =
Displacement/time
The displacement of the car has been given to be = 1215 km West
Time it took to go from Dallas to Paso = 13.5 hours
Then velocity = 1215/13.5
= 90
Therefore velocity = 90km/hour
Option B is the correct answer to this question.
Thank you!
Which of these pairs of atoms are isotpoes? (Physical Science) Pair A Pair B Pair C # protons 6 8 5 2 12 12 # neutrons 8 8 5 3 13 14
Answer:
I guess that the atoms are:
Protons: 6 8 5 2 12 12
Neutrons: 8 8 5 3 13 14
Now, two atoms are isotopes if they share the same number of protons (so both atoms are the same element) but they have a different number of neutrons.
From the given options, the only two that have the same number of protons but a different number of neutrons are:
Protons 12, neutrons 13
and
Protons 12, neutrons 14.
These two are isiotopes.
Electromagnetic waves are classified as longitudinal waves.
Please select the best answer from the choices provided
T
F
Answer:
False
Explanation:
Electromagnetic waves are transverse waves. That means that the electric and magnetic fields oscillate in a plane that is perpendicular to the direction of wave propagation.
Answer:
false electromagnetic waves are not classified as longitudinal waves
An astronaut sitting on the launch pad on Earth's surface is 6,400 kilometers from Earth's center and weighs 400 newtons. Calculate her weight when she reaches an altitude of 6,400 kilometers above the surface of Earth.
Answer:
weight at height = 100 N .
Explanation:
The problem relates to variation of weight due to change in height .
Let g₀ and g₁ be acceleration due to gravity , m is mass of the object .
At the surface :
Applying Newton's law of gravitation
mg₀ = G Mm / R²
At height h from centre
mg₁ = G Mm /h²
Given mg₀ = 400 N
400 = G Mm / R²
400 = G Mm / (6400 x 10³ )²
G Mm = 400 x (6400 x 10³ )²
At height h from centre
mg₁ = 400 x (6400 x 10³ )²/ ( 2 x 6400 x 10³)²
= 400 / 4
= 100 N .
weight at height = 100 N
plz hurry
Which of the following is a result of sterilizing wounds with chemicals?
increased rate of infection
reduced need for hand-washing
reduced rate of infection
increased death rate
Answer:
Sterilization is a common medical practice It decreased bacterial bloom and coverage Hence it reduced rate of infectionA bucket is filled partly with water such that its combined mass is 2.5 kg. It is tied to a rope and whirled in a circle with a radius of 1.4 m. The speed at the top of the circle is 4.0 m/s and the speed at the bottom of the circle is 6.0 m/s. Determine the magnitude of the net force acting on the bucket at the bottom of the circle.
Answer:
1. Simply τ = m x g x r = 54kg x 9.8m/s² x 0.050m = 26 N·m
2. The bucket creates a torque
τ = 75kg x 9.8m/s² x 0.075m = 55 N·m,
so we must create the same torque with the handle.
55 N·m = F x 0.25m
F = 220 N
Explanation:
Hope this is helpful
The air temperature is 70 degrees, and the relative humidity is 90%. Which conclusion can be made?(1 point)
The air holds little water vapor and is relatively dry.
The amount of water vapor in the air is 90% of what the air can hold.
The dew point temperature is 90% of the air temperature.
The temperature must rise in order for air to become saturated with water vapor.
Answer:
The amount of water vapor in the air is 90% of what the air can hold.
Explanation:
The answer is A
Answer: The answer is B: The amount of water vapor in the air is 90% of what the air can hold
Nina's measurements, shown in the table here, BEST represent a wave with
A)
decreasing frequency.
B)
increasing frequency.
C)
increasing amplitude.
D)
decreasing amplitude.
Nina's data in this table most accurately depict a wave with decreasing frequency. Option A is right.
What is frequency?A recurring event's frequency is measured by how many times it occurs in a unit of time.
To emphasize distinctions with spatial and angular frequencies, respectively, it is also sometimes referred to as ordinary frequency or temporal frequency.
If the duration, or time interval, required to complete one cycle or vibration is half a second, the frequency is 2 per second; if it is one hundredth of an hour, the frequency is 100 per hour.
The frequency and period, or time interval, are often reciprocally equal, therefore frequency = 1/period = 1 in most circumstances.
The Moon rotates about Earth about a little bit more than 12 times a year. In a violin A string vibrates at a frequency of 440 cycles per second.
Thus, the correct option is A.
For more details regarding frequency, visit:
https://brainly.com/question/5102661
#SPJ5
When blue light (450 nm) is shone on a particular metal surface, electrons are ejected with a kinetic energy of 2.5 x 10-20 J. Calculate the work function for this metal.
Answer:
the work function of the metal is 4.167 x 10⁻¹⁹ J .
Explanation:
Given;
wavelength of the incident light, λ = 450 nm = 450 x 10⁻⁹ m
kinetic energy, K.E = 2.5 x 10⁻²⁰ J
The energy of the incident light is calculated as;
[tex]E = hf = \frac{h c}{\lambda} \\\\where;\\\\c \ is \ speed \ of \ light = 3 \times 10^8 \ m/s\\\\ h \ is \ Planck's constant = 6.626 \times 10^{-34} Js \\\\E = \frac{(6.626 \times 10^{-34})(3\times 10^8)}{450 \times 10^{-9}} \\\\E = 4.417 \times 10^{-19} \ J[/tex]
Apply Einstein photoelectric equation to determine the work function of the metal;
E = W + K.E
where;
W is the work function of the metal
W = E - K.E
W = 4.417 x 10⁻¹⁹ J - 2.5 x 10⁻²⁰ J
W = 44.17 x 10⁻²⁰ J - 2.5 x 10⁻²⁰ J
W = 41.67 x 10⁻²⁰ J
W = 4.167 x 10⁻¹⁹ J
Therefore, the work function of the metal is 4.167 x 10⁻¹⁹ J .
The work function of the photon is 4.167*10^19J
The energy of this photon can be calculated as
E = hc/λ
Data given;
λ = 450nm = 450*10^-9mh = 6.626*10^-34JSK.E = 2.5*10^-20Jc = 3.0*10^8m/sEnergy of the Photonsubstituting the values into the equation;
[tex]E = hc / y\\E = \frac{6.626*10^-^3^4*3.0*10^8}{450*10^-^9} \\E = 4.42*10^-^1^9J[/tex]
Work FunctionThe work function of the photon can be calculated as;
E = K.E + Ф
4.42*10^-19 = 2.5*10^-20 + Ф
Ф = [tex]4.42*10^-^1^9 - 2.5*10^-^2^0=4.167*10^-^1^9J[/tex]
The work function of the photon is 4.167*10^-19 J
Learn more on work function of a photon here;
https://brainly.com/question/11683155
Einstein calculated that ripples of gravity travel at exactly the speed of _____
Answer:
299,792,458 m/s = speed of light
Explanation:
A student is leaving the lesson and walking to Maths at a speed of 1m/s. He notices that he is late for the lesson and speeds up to 3 m/s. It takes him 4 seconds to speed up. Calculate his acceleration.
Answer:
Acceleration = 0.5 m/s²
Explanation:
Given the following data;
Initial velocity, u = 1m/s
Final velocity, v = 3m/s
Time, t = 4 seconds
To find acceleration;
In physics, acceleration can be defined as the rate of change of the velocity of an object with respect to time.
This simply means that, acceleration is given by the subtraction of initial velocity from the final velocity all over time.
Hence, if we subtract the initial velocity from the final velocity and divide that by the time, we can calculate an object’s acceleration.
Mathematically, acceleration is given by the equation;
[tex]Acceleration (a) = \frac{final \; velocity - initial \; velocity}{time}[/tex]
[tex]a = \frac{v - u}{t}[/tex]
Substituting into the equation, we have;
Acceleration = (3 - 1)/4
Acceleration = 2/4
Acceleration = 0.5 m/s²
Explain how the design of a racing car makes it less likely to turn over.
The principles which allow aircraft to fly are also applicable in car racing. The only difference being the wing or airfoil shape is mounted upside down producing downforce instead of lift. The Bernoulli Effect means that: if a fluid (gas or liquid) flows around an object at different speeds, the slower moving fluid will exert more pressure than the faster moving fluid on the object. The object will then be forced toward the faster moving fluid. The wing of an airplane is shaped so that the air moving over the top of the wing moves faster than the air beneath it. Since the air pressure under the wing is greater than that above the wing, lift is produced. The shape of the Indy car exhibits the same principle. The shape of the chasis is similar to an upside down airfoil. The air moving under the car moves faster than that above it, creating downforce or negative lift on the car. Airfoils or wings are also used in the front and rear of the car in an effort to generate more downforce. Downforce is necessary in maintaining high speeds through the corners and forces the car to the track. Light planes can take off at slower speeds than a ground effects race car can generate on the track. An Indy ground effect race car can reach speeds in excess of 230 mph using downforce. In addition the shape of the underbody (an inverted wing) creates an area of low pressure between the bottom of the car and the racing surface. This sucks the car to road which results in higher cornering speeds.
The total aerodynamic package of the race car is emphasized now more than ever before. Teams that plan on staying competitive use track testing and wind tunnels to develop the most efficient aerodynamic design. The focus of their efforts is on the aerodynamic forces of negative lift or downforce and drag. The relationship between drag and downforce is especially important. Aerodynamic improvements in wings are directed at generating downforce on the race car with a minimum of drag. Downforce is necessary for maintaining speed through the corners. Unwanted drag which accompanies downforce will slow the car. The efficient design of a chassis is based on a downforce/drag compromise. In addition the specific race circuit will place a different demand on the aerodynamic setup of the car.
A road course with low speed corners, requires a car setup with a high downforce package. A high downforce package is necessary to maintain speeds in the corners and to reduce wear on the brakes. This setup includes large front and rear wings. The front wings have additional flaps which are adjustable. The rear wing is made up of three sections that maximize downforce.
The speedway setup looks much different. The front and rear wings are almost flat and are used as stabilizers. The major downforce is found in the shape of the body and underbody. Drag reduction is more critical on the speedway than on other circuits. Since the drag force is proportional to the square of the speed, minimizing drag is a primary concern in the speedway setup. Lap speeds can average over 228 mph and top speeds can exceed 240 mph on a speedway circuit. Effective use of downforce is especially pronounced in highspeed corners. A race car traveling at 200 mph. can generate downforce that is approximately twice its own weight.
Generating the necessary downforce is concentrated in three specific areas of the car. The ongoing challenge for team engineers is to fine tune the airflow around these areas.
I NEED ANSWER ASAP!!!
At which point(s) will acceleration occur shown in the image???
Answer:
Gravity is an ever present force, and therefore acceleration is guaranteed to happen at every single one of those points (and in fact, everywhere in the universe).
On top of that, friction will be present in all four spots (friction with the rails, with the air, with the axles, etc.), and friction is a perfectly acceptable force that will cause acceleration, slowing the roller coaster down.
So the correct answer is every single point, regardless of what answer the teacher expects.
The object will be moving faster if the acceleration and velocity are pointing in the same direction. The object will also slow down if the acceleration is pointing in the opposite direction as the velocity.
What role of acceleration in the motion of object?When an object's speed, direction of motion, or both change, it accelerates. Even while it may appear to be virtually immediate in some circumstances, such as when a golf ball is struck by a club or during car collisions, changes in an object's speed are always continuous.
Since gravity is a constant force, acceleration will unavoidably occur at each of those locations and throughout the whole universe.
Therefore, In addition, there will be friction at all four locations—friction with the axles, the air, the rails, etc.—and friction is a completely normal force that will accelerate the roller coaster, slowing it down.
Learn more about acceleration here:
https://brainly.com/question/14814063
#SPJ2
Imagine you are dating a mineral sample that contains one-eighth of its original parent isotope. What is the
absolute age of the sample if the half-life of the parent isotope is 15 years?
A. 1.875 years
B. 23 years
C. 45 years
D. 120 years
The age of the sample can be determined using the first order equation of the nuclear decay. The age of the parent isotope here is 45 years.
What is half life ?Unstable radioactive nuclei undergo nuclear decay to produce more stable nuclei with more life time. The time required to decay half of the initial amount of a material is called its half life.
The half life of a sample is related with the decay constant k as follows:
k = 0.693/t1/2
Given that, t1/2 = 15 years
k = 0.693/15 = 0.0462 yr⁻¹
The first order equation of the decay process is written as:
k = 1/t ln w0/wt
where w0 is the initial amount and wt be the amount after time t.
then t = 1/k ln w0/wt
Given that, the sample was decayed to one eighth of the initial amount .
t = 1/k ln 8
= 1/0.0462 ln 8
= 45 years.
Therefore, option C is correct.
Find more on nuclear decay:
https://brainly.com/question/12224278
#SPJ6
whats the result of rounding 52.8015 into five significant figures
Answer:
52.802
Explanation:
"Significant figures" in Mathematics refer to the digits that give accuracy to the value of a measurement. There are specific rules when it comes to determining the significant figures. For example, all non-zero digits are considered significant and zeroes located in-between non-zero numbers are significant. In the number given above, the digit "0" is located between "8" and "1," therefore, it is significant. All the digits above are significant.
The problem is only asking for "five" significant figures. We can do this by counting from the left to the right. By this means, we know that the number will be rounded off to the nearest thousandths, which is "1." The number after 1 is 5, which means that 1 digit will be added to number 1, thus, making the digit into "2." The last digit (5) will then be removed.
Explanation:
five significant of 52.8015=52.801 ..
A 76g ball is attached to a string that is 1.5m long. It is spun so that it completes two full rotations every second. What is the centripetal acceleration felt by the ball? m/s2
What is the Force tension on the string? N
The centripetal acceleration = 236.63 m/s²
The force = 17.98 N
Further explanationGiven
mass = 76 g = 0.076 kg
r = 1.5 m
f = 2 rps = 2 rotation per second
Required
The centripetal acceleration
The Force tension
Solution
Centripetal force is a force acting on objects that move in a circle in the direction toward the center of the circle
[tex]\large {\boxed {\bold {F = \frac {mv ^ 2} {R}}}[/tex]
F = centripetal force, N
m = mass, Kg
v = linear velocity, m / s
r = radius, m
The speed that is in the direction of the circle is called linear velocity
Can be formulated:
[tex]\tt \displaysyle v = 2 \pi.r.f[/tex]
r = circle radius
f = rotation per second (RPS)
The linear velocity : 2 x 3.14 x 1.5 x 2 =18.84 m/s
The centripetal acceleration : ac = v²/R = 236.63 m/s²
The force : F = m x ac = 0.076 x 236.63 = 17.98 N
Fig. 2.1 shows a train
Fig. 2.1
The total mass of the train and its passengers is 750000kg. The train is travelling at a speed of 84m/s.
The driver applies the brakes and the train takes 80s to slow down to a speed of 42m/s.
(a) Calculate the impulse applied to the train as it slows down,
impulse =
[3]
(b) Calculate the average resultant force applied to the train as it slows down,
force =
(2)
Answer:
[tex]\mathrm{(a)\:}32,000,000\:\mathrm{Ns},\\\mathrm{(b)\:}390,000\:\mathrm{N}[/tex]
Explanation:
The impulse-momentum theorem states the impulse on an object is equal to the change in momentum of that object. Momentum is given by [tex]p=mv[/tex]. Since mass is constant, the train's change in momentum is:
[tex]\Delta p=m\Delta v=750,000\cdot42=31,500,000=\fbox{$32,000,000\:\mathrm{Ns}$}[/tex](two significant figures).
Impulse is also given as [tex]\Delta p = F\Delta t[/tex], where [tex]F[/tex] is the average force applied and [tex]\Delta t[/tex] is change in time. Since [tex]t[/tex] is given as [tex]80\mathrm{s}[/tex], we have the following equation:
[tex]F\Delta t=\Delta p\\\\F=\frac{\Delta p}{\Delta t},\\\\F=\frac{31,500,000}{80},\\\\F=393,750=\fbox{$390,000\:\mathrm{N}$}[/tex](two significant figures).
What are five facts about magnets? Please help me
If there is a difference in air pressure between two locations, what happens?
Answer:
High in the atmosphere, air pressure decreases. ... A low pressure system has lower pressure at its center than the areas around it. Winds blow towards the low pressure, and the air rises in the atmosphere where they meet. As the air rises, the water vapor within it condenses, forming clouds and often precipitation.
Explanation:
What distance is required for a train
to stop if its intial Velocity is 23 m/s
and its deceleration is 0.25m/s (Assume the train decelerates at a constant rate.)
Explanation:
what is time in this question
Polar dissolves
A. nonpolar
B. polar
C. all molecules
D. none of the above
Polar substances are likely to dissolve in polar solvents.
Your answer is B.
I was having trouble with this problem, and problems like it: A 3.2 kg pelican, with a 1.73 kg fish in its mouth, is flying 1.52 m/s at a height of 40 m when the fish wiggles free and fall back toward the ocean. How fast is the fish moving when it hits the water?
Answer:
28.1 m/s
Explanation:
[tex]u_x[/tex] = Initial velocity of the fish = 1.52 m/s
y = Height of the bird = 40 m
[tex]a_y[/tex] = Acceleration in y axis = [tex]9.81\ \text{m/s}^2[/tex]
[tex]u_y[/tex] = Initial velocity in y axis = 0
[tex]y=u_yt+\dfrac{1}{2}a_yt^2\\\Rightarrow 40=0+\dfrac{1}{2}\times 9.81t^2\\\Rightarrow t=\sqrt{\dfrac{40\times 2}{9.81}}\\\Rightarrow t=2.86\ \text{s}[/tex]
[tex]v_y=u_y+a_yt\\\Rightarrow v_y=0+9.81\times 2.86\\\Rightarrow v_y=28.057\ \text{m/s}[/tex]
The final velocity in x direction will remain the same as the initial velocity as there is no acceleration in the x direction [tex]u_x=v_x=1.52\ \text{m/s}[/tex]
Resultant velocity is given by
[tex]v=\sqrt{v_x^2+v_y^2}\\\Rightarrow v=\sqrt{1.52^2+28.057^2}\\\Rightarrow v=28.1\ \text{m/s}[/tex]
The fish is moving at a velocity of 28.1 m/s when it hits the water.
Science Tolliver
Complete the sentence to explain when waves interact.
Waves interact with
and other
Intro
Done
Answer:
Objects; waves.
Explanation:
Waves interact with objects and other waves. Thus, waves are used on objects such as mobile phones and can be transformed from one form to another.
There are various types of waves in our physical environment such as gamma rays, x-rays, ultraviolet waves, radio waves etc.
Radio waves can be defined as an electromagnetic wave that has its frequency ranging from 30 GHz to 300 GHz and its wavelength between 1mm and 3000m. Therefore, radio waves are a series of repetitive valleys and peaks that are typically characterized of having the longest wavelength in the electromagnetic spectrum.
Basically, as a result of radio waves having long wavelengths, they are mainly used in long-distance communications such as the carriage and transmission of data. Some examples of communication technologies that uses radio waves are radio set, mobile phones, television etc.
An empty airplane with a mass of 200,000 kg must have a speed of 82 m/s to achieve takeoff. Once it is fully loaded, the airplane has a mass of 350,000 kg. It has 3200 m of runway. a) How much force is needed to get the full airplane safely in the air?
b) How much runway would the empty airplane use if its engines generated the same force?
Answer:
a) A force of 367718.75 newtons is needed to get the full airplane safely in the air.
b) The empty airplane would need a runway of 1828.571 meters.
Explanation:
a) This problem can be solved by using the Work-Energy Theorem, which states that work needed by the airplane to get minimum speed is equal to its change in translational kinetic energy, both measured in joules. The resulting formula is presented below:
[tex]F\cdot \Delta s = \frac{1}{2}\cdot m \cdot (v_{f}^{2}-v_{o}^{2})[/tex] (1)
Where:
[tex]F[/tex] - Minimum net force, measured in newtons.
[tex]\Delta s[/tex] - Runway length, measured in meters.
[tex]m[/tex] - Mass of the airplane, measured in kilograms.
[tex]v_{o}[/tex], [tex]v_{f}[/tex] - Initial and final speeds of the airplane, measured in meters per second.
If we know that [tex]m = 350000\,kg[/tex], [tex]v_{o} = 0\,\frac{m}{s}[/tex], [tex]v_{f} = 82\,\frac{m}{s}[/tex] and [tex]\Delta s = 3200\,m[/tex], then the minimum net force needed by the airplane to get itself safely in the air:
[tex]F = \frac{m\cdot (v_{f}^{2}-v_{o}^{2})}{2\cdot \Delta s}[/tex]
[tex]F = \frac{(350000\,kg)\cdot \left[\left(82\,\frac{m}{s} \right)^{2}-\left(0\,\frac{m}{s} \right)^{2}\right]}{2\cdot (3200\,m)}[/tex]
[tex]F = 367718.75\,N[/tex]
A force of 367718.75 newtons is needed to get the full airplane safely in the air.
b) If we know that [tex]m = 200000\,kg[/tex], [tex]v_{o} = 0\,\frac{m}{s}[/tex], [tex]v_{f} = 82\,\frac{m}{s}[/tex] and [tex]F = 367718.75\,N[/tex], then the length of the runway is:
[tex]\Delta s = \frac{m\cdot (v_{f}^{2}-v_{o}^{2})}{2\cdot F}[/tex]
[tex]\Delta s = \frac{(200000\,kg)\cdot \left[\left(82\,\frac{m}{s} \right)^{2}-\left(0\,\frac{m}{s} \right)^{2}\right]}{2\cdot (367718.75\,N)}[/tex]
[tex]\Delta s = 1828.571\,m[/tex]
The empty airplane would need a runway of 1828.571 meters.
IS IT B!! if not pls helpp!
Answer:
I believe you are correct but we just started this unit
Explanation:
How much of the matter in the universe is comprised
of atoms?
a. 1%
b. 100%
c. 30%
d. 99%
Answer: I believe the correct answer is A.
When fireworks explode, sound and light are produced. These are examples of(1 point)
macroscopic inputs.
macroscopic outputs.
microscopic inputs.
microscopic outputs.
Answer: macroscopic outputs
Explanation:
When fireworks explode, sound and light are produced. These are examples of macroscopic outputs. Because, explosion from fireworks is an exothermic process which releases massive heat energy to the surroundings.
What is exothermic reaction?Exothermic reaction are those which evolve heat energy to the surroundings. The change in enthalpy of the reaction is negative here. Whereas, in an endothermic reaction energy is absorbed by the reactants.
Exothermic reactions sometimes results in massive explosion. The heat energy released to the surroundings from the fire works is macroscopic level.
The small scale process or quantity that cannot be measured using normal scales are called microscopic units. Therefore, the sound, light, and heat from the explosion all are macroscopic outputs.
Find more on exothermic reactions:
https://brainly.com/question/29206227
#SPJ6
Please help ASAP please ASAP
A ‘can-chiller’ is used to make a can of drink colder. The initial temperature of the liquid in the can was 25.0 °C. The can-chiller decreased the temperature of the liquid to 20.0 °C. The amount of energy transferred from the liquid was 6930 J. The mass of liquid in the can was 0.330 kg.
Calculate the specific heat capacity of the liquid. Give the unit.
Please help :)
Answer:
4200 J/°C/kg
Explanation:
The formula for heat transfer is given by :
Q= m*c*ΔT where;
Q= heat transferred = 6930 J
m=mass of the liquid = 0.330 kg
c= specific heat capacity=?
ΔT = 25-20 = 5.0°C
Applying the values in the formula as;
Q= m*c*ΔT
6930 = 0.330 * c * 5
6930 = 1.65 c
6930/1.65 = c
4200 = c
c= 4200 J/°C/kg
7. Mac and Tosh are arguing about the track design. Mac claims that the car is moving fastest at point F because it is furthest along the track Tosh disagrees, claiming that the car moves fastest at point F because point F is at the lowest height Who do you agree with? Make a modification of the track design for point F and gather some evidence to support one claim or the other. Then discuss what changes you made, what observations were made, and the reasoning that supports one of the claim of either Mac or Tosh.
Answer:
Tosh is correct.Swap the locations of points B and F on the track and gather speed data. If Mac is correct, the speed at F (closer to the start) should be lower. (It will not be, confirming Tosh's claim.)Explanation:
The total energy of the car is continuously being exchanged between potential energy and kinetic energy as the car moves along the track. Neglecting energy loss due to friction, the kinetic energy will be greatest when the potential energy is least, at the lowest point on the track. As a consequence we agree with Tosh that the speed will be greatest at F because it is the lowest point.
__
If the track were modified to move the lowest point nearer the start, say by interchanging points B and F, then data could be gathered to show whose theory is supported. The evidence needed is the speed of the car at the new location of point F. Tosh's argument is supported if the speed at the new point F is substantially the same.
