A car is traveling at 104 km/h when the driver sees an accident 50 m ahead and slams on the brakes. What minimum constant deceleration is required to stop the car in time to avoid a pileup

Answers

Answer 1

a =  - 8.34 m/sec²       ( deceleration or negative)  

Equations for UAM  ( uniformly accelerated motion) are:

vf = v₀ ±  a*t           and      s  =  s₀  + v₀*t + (1/2)*a*t²

In our case, the motion is with deceleration, then

vf = v₀ - a*t       and    s = s₀  +  v₀*t  - (1/2)*a*t²  

working on these equatios we get:

vf = v₀ - a*t     (1)           s  -  s₀   =  v₀*t  - (1/2)*a*t²      (2)

v₀ - vf = a*t

t  =  (v₀ - vf)/a

By substitution of (1) in equation (2)

s  -  s₀   =  v₀ * (v₀ - vf)/a  -  (1/2) * a* [(v₀ - vf)/a]²

s  -  s₀   =  (v₀² - v₀*vf)/a  -   (1/2) * a* (1/a²)* (v₀ - vf)²

s  -  s₀   =  1/a * ( v₀² - v₀*vf ) - 1/a* (1/2)  * (v₀ - vf)²

s  -  s₀   =  1/a* [  ( v₀² - v₀*vf ) - (1/2) * (v₀ - vf)²]

a * (s  -  s₀ )  =   v₀² - v₀*vf - v₀²/2 - vf²/2 + v₀*vf

a * (s  -  s₀ )  =  (1/2) * v₀² - (1/2)*vf²

a * (s  -  s₀ )  =  (1/2) * ( v₀² - vf²)

We find an expression to calculate the minimum deceleration to stop the car in time to avoid crashing

s₀ = 50 meters            s  =  0        v₀ =  104 Km/h    vf = 0

1 Km  = 1000 m    and   1 h = 3600 sec

v₀ = 104 Km/h    =  28.88 m/sec

a  =  (1/2) [ (28.88)² - 0 ] / 0 - 50

a =  - 8.34 m/sec²       ( deceleration or negative)  


Related Questions

In Newton's cannonball experiment, if the velocity is equal the orbital velocity the Cannon ball
will
O stay in orbit
O fall to the earth
O escape the earth
O none of the above

Answers

In Newton's cannonball experiment, if the velocity is equal to the orbital velocity then the cannonball will stay in Orbit.

Newtons cannonball experiment stated that the distance that a cannonball will travel, before being drawn into the Earth by the forces of gravity, is dependent on the initial velocity.

Therefore, if the cannonball is launched at a velocity that matches the orbital velocity, then it will not be able to be drawn in by gravity due to the Earth moving away from the cannonball at the same speed at which the cannonball itself is falling.

This means that the cannonball will continue to fall without reaching the Earth, therefore staying in orbit, much like that of the moon or planets around the sun.

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A ball is launched from ground level at 30 m/s at an angle of 35° above the horizontal. how far does it go before it is at ground level again

Answers

Answer:

Explanation:

Ignoring air resistance

Initial vertical velocity is 30sin35 = 17.2 m/s

Gravity reduces this velocity to zero in a time of

t = v/g =17.2 / 9.8 = 1.755 s

it takes the same time to come back down to ground level for a total flight time of 2(1.755) = 3.51 s

The horizontal velocity is 30cos35 = 24.57 m/s

the distance traveled horizontally is

d = vt = 24.57(3.51) = 86.298... = 86 m

A wheel in the shape of a flat, heavy, uniform, solid disk is initially at rest at the top of an inclined plane of height 2.00 m when it begins to roll down the incline. If rolling and sliding friction are neglected, what is the linear velocity, in m/s, of the center-of-mass of the wheel when it reached the bottom of the incline?

Answers

Answer:

Explanation:

If friction is neglected, the wheel cannot roll and can only slide frictionlessly and will have the same velocity at the bottom of the ramp as if it had been in free fall as it has converted the same amount of potential energy.

mgh = ½mv²

v = √(2gh) = √(2(9.81)(2.00)) = 6.26418... = 6.26 m/s

However if we do not ignore all friction and the wheel rolls without slipping down the slope, the potential energy becomes linear and rotational kinetic energy

mgh = ½mv² + ½Iω²

mgh = ½mv² + ½(½mR²)(v/R)²

2gh = v² + ½v²

2gh = 3v²/2

v = √(4gh/3) =√(4(9.81)(2.00)/3) = 5.11468... = 5.11 m/s

The 0.15kg baseball has a speed of v=30 m/s just before it is struck by the bat. It then travels along the trajectory shown before the outfielder catches it. Determine the magnitude of the average impulsive force imparted to the ball if it is in contact with the bat for 0.75 ms

Answers

The magnitude of the average impulsive force imparted to the ball if it is in contact with the bat is 6000 N

The mass of the baseball, m = 0.15 kg

The speed at which it moves, v = 30 m/s

Time at which the baseball was in contact with the bat, t = 0.75 ms

t = 0.75/1000 s

t  = 0.00075 s

The impulsive force is given by the formula:

[tex]F=\frac{mv}{t}[/tex]

Substitute m = 0.15 kg, v = 30, and t = 0.00075s into the formula above:

[tex]F=\frac{0.15 \times 30}{0.00075} \\\\F=6000N[/tex]

The magnitude of the average impulsive force imparted to the ball if it is in contact with the bat is 6000 N

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Which of the following is an incorrect statement?

The pulley is a special type of wheel and axle.
The mechanical advantage of a pulley with three ropes is one.
The mechanical advantage of a block and tackle pulley with two pulleys is two.
The mechanical advantage of a fixed pulley is one.
PLZ HELP WILL MARK BRAINLIEST

Answers

Answer:

Explanation:

The mechanical advantage of a pulley with three ropes is one.

is incorrect. It is 3

Shorter the vibrating part more will be the pitch. How?​

Answers

Answer:When the length of a string is changed, it will vibrate with a different frequency.Shorter strings have higher frequency and therefore higher pitch.

2) A traffic light of weight 100 N is supported by two ropes as shown. Let T1 and T2 are the tensions.
a. Resolve the vectors into its components and find their values [ 4 marks]
b. Find sum of the x-components [1 mark]
c. Find sum of the y-components [1mark]
d. Use the above equations to find the tensions in the ropes?
the two angles on x and y are both 37 I cant upload the diagram

Answers

Hi there!

a.

We know that:

[tex]\Sigma F_y = 0 \\\\\Sigma F_x = 0[/tex]

Begin by determining the forces in the vertical direction:

W = weight of traffic light

T₁sinθ = vertical component of T₁

T₂sinθ = vertical component of T₂

b.

The ropes provide a horizontal force:

T₁cosθ = Horizontal component of T1

T₂cosθ = Horizontal component of T2

Thus:

0 = T₁cosθ  - T₂cosθ

T₁cosθ = T₂cosθ

T₁ = T₂

c.

Since the angles for both ropes are the same, we can say that:

T₁ = T₂

Sum the forces:

ΣFy = T₁sinθ + T₁sinθ - W = 0

2T₁sinθ = W

d.

Now, we can begin by solving for the tensions:

2T₁sinθ = W

[tex]T_1 = T_2 = \frac{W}{2sin\theta} = \frac{100}{2sin(37)} = \boxed{83.08 N}[/tex]

what is the value of acceleration due to gravity g at the pole of earth​

Answers

Answer:

The value of Acceleration due to gravity at the pole of the earth is 9.870m/s^2 .

Explanation:

I hope this helps you !!
Answer: about 9.832 m/s2:
In combination, the equatorial bulge and the effects of the surface centrifugal force due to rotation mean that sea-level gravity increases from about 9.780 m/s2 at the Equator to about 9.832 m/s2 at the poles, so an object will weigh approximately 0.5% more at the poles than at the Equator


Bye, have a wonderful Christmas!

please help

Two masses m1 and m2, are a distance R apart and mq exerts a gravitational force F on m2. What is the gravitational force is the gravitational force on M1?​​

Answers

Answer:

F

Explanation:

for every action there exists an equal and opposite reaction. The force acting on the two masses is identical in magnitude, but opposite in direction.

9.The force of gravity between two asteroids is 10,000 newtons (N).

When the distance between the asteroids is halved, what will be the force of gravity between them?

Answers

Answer:

F1 = G m1 m2 / R^2        force of attraction

F2 = G m1 m2 / (R/2)^2

F2 / F1 = 4       the force of gravity will be quadrupled

Describe a vibration that is not periodic. NO LINKS PLEASE

Answers

Answer:

1)The position change of almost any manually operated room light switch.

2) Sunlight striking a point on the ground on a partly cloudy and windy day

Explanation:

2. A ray of light is incident at 60° in the air on an air glass plane surface find the angle of refraction in the glass. (mew for glass=1.5)
[tex] [/tex]

Answers

Answer:

35.2644

I suppose mew is refractive index

Explanation:

( sin i ) / (sin r) = refractive index

( sin 60) / (sin r) = 1.5

( sin 60) / 1.5 =sin r

r=35.844

sorry if I'm wrong

A roller coaster starts from rest at its highest point and then descends on its (frictionless) track. Its speed is 38 m/s when it reaches ground level. What was its speed when its height was half that of its starting point

Answers

Explanation:

look !

speed= 38m/s

start from rest= 0

A 1.95 kg box sits on an incline of 24 ° with the horizontal. If the box accelerates down the incline at 0.245 m/s 2 , what is the coefficient of kinetic friction between the box and the inclined plane?

Answers

Answer:

Explanation:

                            F = ma

mgsinθ - μmgcosθ = ma

      gsinθ - μgcosθ = a

                   μgcosθ = gsinθ - a

                              μ = (gsinθ - a) / gcosθ

                              μ = (9.81sin24 - 0.245) / 9.81cos24

                              μ = 0.4178906...

                              μ = 0.418

The coefficient of kinetic friction will be equal to 0.418.

What is friction?

Friction is the force that prevents solid surfaces, fluid layers, and material elements from sliding against each other. There are various kinds of friction: Dry friction is the force that opposes the relative lateral motion of two in-touch solid surfaces.

Given that a 1.95 kg box sits on an incline of 24 ° with the horizontal. If the box accelerates down the incline at 0.245 m/s 2

The coefficient of kinetic friction will be calculated as,

F = ma

mgsinθ - μmgcosθ = ma

gsinθ - μgcosθ = a

μgcosθ = gsinθ - a

Solve for the value of the coefficient of friction,

μ = (gsinθ - a) / gcosθ

μ = (9.81sin24 - 0.245) / 9.81cos24

μ = 0.4178906...

μ = 0.418

Therefore, the coefficient of kinetic friction will be equal to 0.418.

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What does water’s high specific heat capacity explain about water?(1 point)

why water bonds with other molecules
why water bonds with other molecules

why water is unable to absorb energy
why water is unable to absorb energy

why water is liquid at room temperature
why water is liquid at room temperature

why water is often used as a solvent

Answers

Water’s high specific heat capacity explain why water is liquid at room temperature

option C is the correct answer.

What is specific heat capacity?

The specific heat capacity of an object is the amount of heat required to raise the temperature of a unit mass of the substance by 1 kelvin.

The relationship between specific heat capacity and heat capacity of a substance is given as;

c = Q/mΔθ

where;

Q is the quantity of heat c is the specific heat capacitym is the mass of the substanceΔθ is the change in temperature

A high specific heat capacity implies that the substance absorbs more energy to change its state.

Thus, water has a high specific heat, meaning it takes more energy to increase the temperature of water compared to other substances. When water absorb more heat energy, it changes its state.

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When laser light of wavelength 632.8 nm passes through a diffraction grating, the first bright spots occur at ± 17.8 ∘ from the central maximum. What is the line density

Answers

Answer:

Depends on the weight i would be 7.120

______ uses radioactive materials to create contrast in the body and help form images of the structure and function of organs.

Answers

Answer:

Nuclear medicine or PET scanning (Positron Emission Tomography)

Explanation:

Not super sure what your question is looking for but I think it can be either. PET is a technology used in the nuclear medicine field, and nuclear medicine is a broad field of using the technology the question described.

When shopping for margarine what information should you look for on the label

Answers

Answer:

When buying a margarine, people should look for trans fat and saturated fat content. If it is over 2%, then it is not healthy. If it is lower that means it is healthy and fresh!

Explanation:

State the term used to describe the turning force exerted by the man

Answers

]A force called the effort force is applied at one point on the lever in order to move an object, known as the resistance force, located at some other point on the lever.

The way levers work is by multiplying the effort exerted by the user. Specifically, to lift and balance an object, the effort force the user applies multiplied by its distance to the fulcrum must equal the load force multiplied by its distance to the fulcrum. Consequently, the greater the distance between the effort force and the fulcrum, the heavier a load can be lifted with the same effort force.

AnswAnswer This!!!!!!
I'll give brainliest to whoever gets it right.

Answers

answer: 1.0 mol

8/2 = 4/2 = 2/2 = 1

A section of a rollercoaster is shown below. If the 17,500 kg rollercoaster momentarily comes to rest at point A, where it is 19 m in the air, how fast is it going at point D?

Answers

Answer:

Explanation:

Impossible to say without knowing how high point D is.

If we ignore friction, the energy converted from potential energy will exist as kinetic energy.

let d be the height in meters of point D "in the air"

mg(19 - d) = ½mv²

m is common so divides out

g(19 - d) = ½v²

v = √(2g(19 - d))

no sense in making g any more precise than the height. g = 9.8

v = √(2(9.8)(19 - d))

v = √(19.6(19 - d))

at room tmeperature none of the metals are

Answers

What metal is not at room temperature?

Mercury is a metallic chemical element that is an only metal that is not a solid at room temperature.

The motor of an electric drill has a power input of 1200 W. How much work 3 points
is done by the drill in a time of 2 minutes? *
Your answer
This is a required question

Answers

Answer:

Explanation:

1 Watt = 1 J/s

1200 J/s(2 min)(60 s/min) = 144 KJ

Why does the earth stay in orbit around the sun instead of drifting away from it into space?
A Electric force between the Sun and Earth
B Magnetic force between the Sun and Earth
Gravitational force between the Sun and Earth

Answers

Answer:

b it is b part answer i think so

Which of these is a push or a pull? Acceleration Force Mass Inertia

Answers

Answer:

the answer is force . force is applied as a push or pull

A 10kg object is 15 meters up a hill. Find its potential energy

Answers

Answer:

Explanation:

Relative to an origin at the bottom of the hill,

PE = mgh = 10(9.8)(15) = 1470 J

1. In Newton's cannonball experiment, if the velocity is larger than the orbital velocity the Cannon
ball will
1. stay in orbit
2. fall to the earth
3. escape the earth
4. none of the above

Answers

Answer:

escape the earth I think

In Newton's cannonball experiment, is the velocity is larger than the orbital velocity the Cannon ball will escape the Earth. Thus, the correct option is 3.

What was Newton's Cannonball experiment?

In this experiment, Newton visualizes a stone that is a cannonball which is being projected on top of a very high mountain. And, if there were no gravitational force or air resistance in that area, the body should follow a straight line path away from the Earth, in the direction in which it was projected.

If the cannonball is launched at a velocity that matches the orbital velocity of the planet, then it will not be able to be drawn in by gravitational force due to the Earth which results into moving away from the cannonball at the same speed at which the cannonball itself is falling.

If the velocity of the cannonball is larger than the orbital velocity than the ball will escape the Earth.

Therefore, the correct option is 3.

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n a distant solar system, a planet of mass 5.0 x 1024 kg orbits a sun of mass 3.0 x 1030 kg at a constant distance of 2.0 x1011 m. How many earth days does it take for the planet ot execute one complete orbit about the sun

Answers

Answer:

F = M2 ω^2 R       centripetal force of sun on planet

ω = (F / (M2 R))^1/2 = 2 pi f = 2 pi / P        where P is the period

P = 2 pi (M2 * R / F)^1/2

F = G M1 M2 / R^2        gravitational force on planet

P = 2 pi {R^3 / (G M1)]^1/2

P = 6.28 [(2.0E11)^3 / (6.67E-11 * 3.0E30)]^1/2

P = 6.28 (8 / 20)^1/2 E7 = 3.9E7 sec

1 yr = 3600 * 24 * 365 = 3.15E7 sec

P = 3.9 / 3.2 = 1.2 years

If you have to measure the temperature > above 80°c, do you use an alcohol or mercury thermometer? why?

Answers

Answer:

I use mercury thermometer to measure the temperature above 80°C because the boiling point of alcohol is 78°C . So, it can't measure the temperature above 78°C.


Word Bank:
Electrical
Mechanical
Chemical
Light
Thermal
Sound

Answers

Answer:

Light to

Electrical to

mechanical and sound

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