In April 1974, Steve Prefontaine completed a 10.0 km race in a time of 27 min , 43.6 s . Suppose "Pre" was at the 7.71 km mark at a time of 25.0 min . If he accelerated for 60 s and then maintained his increased speed for the remainder of the race, calculate his acceleration over the 60 s interval. Assume his instantaneous speed at the 7.71 km mark was the same as his overall average speed up to that time.

Answers

Answer 1

Answer:

0.18 m/s²

Explanation:

The total time taken to cover a 10 km race is 27 min, 43.6 seconds.

At 25 min, Pre was at 7.71 km mark. Therefore the average speed = 7.71 km / 25 min = 7710 m / (25 * 60) s = 5.14 m/s

The distance remaining = 10 km - 7.71 km = 2.29 km = 2290 m

The remaining time = 27 min, 43.6 seconds - 25 min = 2 min 43.6 second = 163.6 seconds

She accelerates for 60 seconds, therefore the distance covered (S) during the acceleration (a) is:

S₁ = 5.14(60) + 0.5a(60)² = 308.4 + 1800a

She maintains the speed for the remaining distance (S₂). The remaining time = 163.6 seconds - 60 seconds = 103.6 seconds. The final speed after the acceleration = (5.14 + 60a) m/s

S₂ = (5.14 + 60a)* 103.6 = 532.5 + 6216a

S₁ + S₂ = 2290 m

(308.4 + 1800a) + (532.5 + 6216a) = 2290

8016a + 840.9 = 2290

8016a = 1449.1

a = 0.18 m/s²


Related Questions

What would be the weight (in Newtons) of a person with a mass of 80 kg on Earth, where the acceleration due to gravity is approximately 9.8 m/s/s? *
please help asap

Answers

Answer:

ml tayo 1v1 durugin kita

Explanation:

ano takot ml 1v1

2
Select the correct answer.
Which statement is true about acceleration?
OA.
It is the rate of change of speed per unit time.
OB.
It is the rate of change of displacement per unit time.
Ос.
It is the rate of change of velocity per unit time.
OD.
It is the rate of change of position per unit time.
Reset
Next

Answers

Answer:

the answer is C ----- it is the rate of change of velocity per unit time

Explanation:

acceleration

[tex] = \frac{velocity(v)}{time(t)} [/tex]

As an IT technician for your company, you have been notified that the Windows domain does not seem to be functioning properly. Being familiar with domains, you are fairly confident you know what the issue is. But just to be safe, you take the applicable time to gather additional information and to identify what, if anything, has changed.

Which of the following is the BEST next step?

A. Determine the appropriate fix.
B. Create a hypothesis.
C. Implement the fix.
D. Identify what has changed.
E. Gather information.

Answers

Answer: Create a hypothesis

Explanation:

From the information given, information has been gathered and the identification to ascertain if there's a change. Then, an hypothesis has to be created in order to know what the problem is.

One has to carry out some research in order to know what went wrong and should also validate the hypothesis by consulting with ones peers. By doing this, the most likely causes of the issues will be gotten.

NEED ANSWER QUICK, WILL GIVE BRAINLIEST! How many nails do sapiens have?
A. 6
B. 10
C. 3
D. None

Answers

Answer:

nice calculations!

Explanation:

None of the above. Or is it regarding toe alone with finger nails?

which is the correct equation for the elastic potential energy stored in a spring
A EPE = mv
B EPE = 1/2kx^2
C EPE = F(delta)t
D EPE = -kx

Answers

(B)

Explanation:

[tex]pe = \frac{1}{2} k {x}^{2} [/tex]

The equation of the elastic potential energy stored in the spring can be represented as: EPE = (1/2)kx². Therefore, option (B) is correct.

What is elastic potential energy?

The elastic potential energy can be described as the total energy obtained as a result of deformation in the shape of an object. The elastic potential energy implies any object which is capable of regaining its actual shape and size after deformation.

The deformation is only possible as a result of the gained potential energy which is called the elastic potential energy. The elastic potential energy can be stored energy of a compressible or stretchable in other words stored energy of perfectly elastic materials.

The mathematical equation of the elastic potential energy formula is given by:

U = 1/2 (Force × Displacement)

U = (1/2) (kx) (x)

U = (1/2)kx²

Where k is the spring constant and x is the displacement as a result of applied external force.

Learn more about elastic potential energy, here:

https://brainly.com/question/14687790

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The reading on your speedometer is the

A) average velocity
B) none of these is correct
C) speed
D) instantaneous velocity

Answers

The answer is speed!!
If you need why it is speed comment, if helped mark me the brainiest!!
The answer is c) speed

Q= Which one of the following statement is incorrect?
A. When a switch is closed in a circuit, no current flows.
B. A switch is a device for turning on and off an electric current.
C. An electric current is a complete loop around which a current can flow.
D. An electric current is a flow of charge

Answers

Answer:

A.

Explanation:

I think it might be the big number A

what's a magnet field​

Answers

A magnetic field is a picture that we use as a tool to describe how the magnetic force is distributed in the space around and within something magnetic.

Water is being heated on the stove at 90 ⁰C. What is this temperature on the Fahrenheit degrees?

Answers

Answer:

194 degrees farenheit! hot

Explanation:

(90°C × 9/5) + 32 = 194°F

Answer:

194

Explanation:

to get from celcius to Fahrenheit

multiply temperature by 2 and add 30

Kiedy błyska blisko slyszymy krótki grzmot, kiedy daleko długi. Dlaczego ?

Answers

Answer:

it is becuase light travel faster then sound thus light come to us first

Explanation:

to dlatego, że światło podróżuje szybciej niż dźwięk, to światło dociera do nas jako pierwsze

What state of matter did the earth need to be in order for planetary differentiation to occur?
Answer: Gas, liquid, or solid?

Answers

Gas. I know this because first you will need to do the equator so I will say gas

The vine has a fixed end, so Tarzan's path is circular. So the vine must not only support Tarzan's weight (or some component of it) but must also provide centripetal force to curve Tarzan's velocity. At Tarzan's lowest point, this can be expressed as:_________.

Answers

Answer: hello your question lacks some data attached below is the missing data

answer : T - mg = ma[tex]_{c}[/tex]

Explanation:

Given that the vine has a fixed end and Tarzan's path is circular

At Tarzans lowest point the point can be expressed as shown below.

It can be expressed as : T - mg = ma[tex]_{c}[/tex]

The x and y components of a force are 2 N
and - 3 N. The force is​

Answers

Answer:

Your answer is in the pic

a ball of mass 0.2 kg is dropped from a height of 20m on impact to the ground it loses in 30 joule of energy calculate the height it reaches on rebound​

Answers

Answer:

new PE at top=original PE - energy lost

mgh=.2(9.8)20-30

Explanation:

mgh=.2(9.8)20-30 = 9.2

What are laser knives?

Answers

Answer:

It is an ultra-thin and lightweight knife that cuts through food easily and beautifully.

is an ultra-thin and lightweight knife that cuts through food easily and beautifully. Because the knife is so thin, the food it cuts offers very little resistance. Even when it’s not a peak sharpness, laser knives can perform better than other types of knives.

what happens when a light ray is incident normally to the interface of two media?

Answers

Explanation:

ahhh, maybe you mean , what happens when a light ray hits the interface of two media perpendicular to the normal.

if that is the case then the light ray will not bend but it will travel in the same direction in the second medium as it was travelling in it's first medium

hope this helps bro

What is the three-body problem? Explain at a level so an 8th grader could understand

Answers

Answer:

In physics and classical mechanics, the three-body problem is the problem of taking the initial positions and velocities (or momenta) of three point masses and solving for their subsequent motion according to Newton's laws of motion and Newton's law of universal gravitation.[1] The three-body problem is a special case of the n-body problem. Unlike two-body problems, no general closed-form solution exists,[1] as the resulting dynamical system is chaotic for most initial conditions, and numerical methods are generally required.

Hope this answer is right!

The specific heat capacity of sea water is 4100 J/Kg°C and the boiling point of 100.6 °C. (i) Calculate the energy required to raise the temperature of 0.900 kg of this sea water from 10 °C up to its boiling point. Also mention the equation to be used. *

Answers

Answer:

334.314 (kJ)

Explanation:

1) the formula for the required energy is: Q=c*m(Bp-t), where c - 4100 J/kg*C; m - 0.9 kg; Bp - 100.6 C; t - 10 C.

2) according to the formula above:

Q=4100*0.9*(100.6-10)=41*9*906=334314 (J).

What are the wavelengths of x-rays and gamma rays?
a.
x-rays - 3 pm to 20 nm
gamma rays- less than 3 pm
c.
x-rays - 3 mm
gamma rays- 20 to 50nm
b.
x-rays - 400nm
gamma rays- 700nm
d.
None of the above

Answers

Answer:

1. less. 2 greater. 3. the same. 8. An FM radio station broadcasts its signal at a fre​- ... wave 3. | 3x108 = 269.15x107). = 3.20m. 2. An electromagnetic AM-band radio wave could have Base your answers to questions 9 and 10 on the informa- ... X rays. -Microwaves. -Long


A man ran a 5 mile race. The race looped around a city park and back
to the starting line. What is the man's total displacement?
A. 0 miles
B. 2.5 miles
C. 5 miles
D. 10 miles

Answers

10 miles common since

The final displacement of the man would be zero miles because displacement is given by the difference between the final and the initial position of the body, therefore the correct answer is option A.

What is displacement?

An object's position changes if it moves in relation to a reference frame, such as when a passenger moves to the back of an airplane or a professor moves to the right in relation to a whiteboard. Displacement describes this shift in location.

As given in the problem we have to find the total displacement of the man if he ran a 5-mile race. The race looped around a city park and back

to the starting line,

The total displacement of the man = final position - initial position

As we know that the initial and final position of the man coincides therefore the final displacement of the man is zero, therefore the correct answer is option A.

Learn more about displacement here, refer to the link;

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2. Two charges at fixed locations produce an electric field as shown
below. If point charge. Y. is negative, which direction will it travel?

Answers

Answer:

sum of the two forces as both point to the right is a force that points to the right,

Explanation:

The force on the cast load at point Y is given by

        F = q_y  E

force is a vector magnitude so its result is

        ∑ F = Fₐ + F_b

indicate that the charge at y is negative, we analyze the direction of the force created by each charge

Charge A

as the electric field is incoming the charge is negative and as the test charge is negative both repel each other, consequently the force points to the right

Charge B

in this case the electric field lines are salient, therefore the charge is positive, consequently the force on the charge at y is attractive and points to the right

the sum of the two forces as both point to the right is a force that points to the right, that is, in the direction of the charge located at B

Based on the law of conservation of energy, how can we reasonably improve a machine’s ability to do work?

Answers

Answer:

We can reasonably improve a machines ability to do work by reducing the friction between the moving parts of machine.

Explanation:

According to the law of conservation of energy, the energy can neither be created nor destroyed.

A rocket of mass M when empty carries a mass M of fuel. The rocket and fuel travel at speed v.
The engine of the rocket is fired and all of the fuel is expelled. The speed of the rocket increases
to 2v.

What happens to the kinetic energy of the rocket?
A It doubles.
B It halves.
C It increases by a factor of four.
D It stays the same.

Answers

The kinetic energy of the rocket should be A. it doubles.

What is kinetic energy?

Kinetic energy represents the energy where an object or a particle should be the reason for its motion. It transfers energy than it should be done on an object by applying a net force, so the object speeds up and thereby gains kinetic energy. In the case when the speed increased to 2v so the kinetic energy should also doubles.

Learn more about speed here: https://brainly.com/question/17052831

what the balance electrons for calcium​

Answers

Answer:

its two valence electrons

Explanation:

Calcium is a group 2 element with two valence electrons. Therefore, it is very reactive and gives up electrons in chemical reactions.

UR WELCOME!! :)

A man who weighs 75kg on the surface of the earth whose mass is 6*10^24kg. If the radius of earth is 6480km ,calculate the force of attraction between them.

Answers

Answer:

but I don't know what the answesorryr

Answer:

the force of attraction between them???

50N force accelerated a body at a rateof 8 metres per second square. Calculate the mass of the body​

Answers

Answer:

m=6.25kg

Explanation:

Force= mass × acceleration

50=m×8

make m subject of the formula...

m=50/8

m=6.25kg

Answer:

[tex]\boxed {\boxed {\sf 6.25 \ kilograms}}[/tex]

Explanation:

According to Newton's Second Law of Motion, force is the product of mass and acceleration.

[tex]F= m \times a[/tex]

We know the force is 50 Newtons and the acceleration is 8 meters per second squared. Let's convert the units to make the problem and unit cancellation easier.

1 Newton is equal to 1 kilogram meter per square second (1 kg*m/s²), so the force of 50 N is equal to 50 kg*m/s².

Now we know 2 values:

F= 50 kg*m/s²a= 8 m/s²

Substitute the values into the formula.

[tex]50 \ kg *m/s^2= m \times 8 \ m/s^2[/tex]

Since we are solving for the mass, we must isolate the variable, m. It is being multiplied by 8 meters per square second and the inverse of multiplication is division. Divide both sides by 8 m/s².

[tex]\frac {50 \ kg *m/s^2}{8 \ m/s^2}= \frac{m \times 8 \ m/s^2}{8 \ m/s^2}[/tex]

[tex]\frac {50 \ kg *m/s^2}{8 \ m/s^2}= m[/tex]

The units of meters per square second (m/s²) cancel.

[tex]\frac {50 \ kg }{8 }=m[/tex]

[tex]6.25 \ kg =m[/tex]

The mass is 6.25 kilograms.

HELP PLEASE ?? can u answer this multiple choice for me please?

Answers

Answer:

.04 kg m/s

Explanation:

Momentum is simply mass multiplied by velocity given by p = mv. You can consider momentum as mass in motion.

Before the collision, the data given for the toy train:

v = 0.5m/s

m = 75g

We need to convert grams into the SI unit of mass, kg.

75g / 1000g * 1kg = 0.075kg

Using p = mv, we can determine:

p = 0.075kg * 0.5m/s = 0.0375 kg m/s

Rounding to the value of 1 sig-fig, it comes out to be 0.04 kg m/s.

hich of these best describes Earth’s mantle?

Most dense layer, consists of the outer and inner parts
Thinnest under the oceans and thickest under continents
Middle layer, density increases with depth as pressure increas

Answers

Answer:

Middle layer, density increases with depth as pressure increases

Explanation:

The Earth's mantle is the middle layer of the earth. It is the largest layer of the earth consisting of about 83 % of the earth's volume and continues to a depth of 2900 km. Also, the mantle is hot and made of solid rock. It is hot since it is close to the core and its pressure and density increases with depth causing it to be more solid.

So, the Earth's mantle is the middle layer, density increases with depth as pressure increases.

A fixed mass of gas has a volume of 25 cm³. The pressure of the gas is 100 kPa.
The volume of the gas is slowly decreased by 15 cm³ at constant temperature.
What is the change in pressure of the gas?
A)67 kPa
B)150 kPa
C)170 kPa
D)250 kPa​

Answers

Answer:

67 kPa

Explanation:

Given that,

Initial volume, V₁ = 25 cm³

Initial pressure, P₁ = 100 kPa

Final volume, V₂ = 15 cm³

We need to find the change in pressure of the gas. The relation between the volume and pressure of a gas is given by :

[tex]P\propto \dfrac{1}{V}\\\\\dfrac{P_1}{P_2}=\dfrac{V_2}{V_1}\\\\P_2=\dfrac{P_1V_1}{V_2}\\\\P_2=\dfrac{100\times 25}{15}\\\\=166.66\ kPa[/tex]

or

= 167 kPa

The change in pressure,

= P₂ - P₁

= 167 kPa - 100 kPa

= 67 kPa

Hence, the correct option is (a).

A spring with a spring constant of 200 is compressed 0.5 . What is the potential energy stored in the spring

Answers

Answer:

E = 25 J

Explanation:

Given that,

Spring constant, k = 200

Compression, x = 0.5

We need to find the potential energy stored in the spring. The formula for the stored potential energy in the spring is given by :

[tex]E=\dfrac{1}{2}kx^2[/tex]

Put all the values,

[tex]E=\dfrac{1}{2}\times 200\times 0.5^2\\\\E=25\ J[/tex]

So, 25 J of potential enersy is stored in the spring.

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