You testify as an expert witness in a case involving an accident in which car A slid into the rear of car B, which was stopped at a red light along a road headed down a hill (Fig. 6-25). You find that the slope of the hill is u " 12.03, that the cars were separated by distance d " 24.0 m when the driver of car A put the car into a slide (it lacked any automatic anti-brake-lock system), and that the speed of car A at the onset of braking was v0 " 18.0 m/s.With what speed did car A hit car B if the coefficient of kinetic friction was (a) 0.60 (dry road surface) and (b) 0.10 (road surface covered with wet leaves)

Answers

Answer 1

Answer:

A) 12.08 m/s

B) 19.39 m/s

Explanation:

A) Down the hill, we will apply Newton’s second law of motion in the downward direction to get:

mg(sinθ) – F_k = ma

Where; F_k is frictional force due to kinetic friction given by the formula;

F_k = (μ_k) × F_n

F_n is normal force given by mgcosθ

Thus;

F_k = μ_k(mg cosθ)

We now have;

mg(sinθ) – μ_k(mg cosθ) = ma

Dividing through by m to get;

g(sinθ) – μ_k(g cosθ) = a

a = 9.8(sin 12.03) - 0.6(9.8 × cos 12.03)

a = -3.71 m/s²

We are told that distance d = 24.0 m and v_o = 18 m/s

Using newton's 3rd equation of motion, we have;

v = √(v_o² + 2ad)

v = √(18² + (2 × -3.71 × 24))

v = 12.08 m/s

B) Now, μ_k = 0.10

Thus;

a = 9.8(sin 12.03) - 0.1(9.8 × cos 12.03)

a = 1.08 m/s²

Using newton's 3rd equation of motion, we have;

v = √(v_o + 2ad)

v = √(18² + (2 × 1.08 × 24))

v = 19.39 m/s


Related Questions

what the difanshon of mass?

Answers

Answer:

Mass is a measure of the amount of matter in an object.

Explanation:

To determine the height of a bridge above the water, a person drops a stone and measures the time it takes for it to hit the water. If the time is 2.3 s, what is the height of the bridge? Neglect air resistance.

a. 32 m
b. 52 m
c. 26 m
d. 14 m
e. 10 m

Answers

s = 1/2 a t^2 = 1/2 x 9.8 x 2.3^2 = 26m

A stone dropped from a 26 m bridge, takes 2.3 s to reach the water.

A stone is dropped from a bridge and it experiences a uniformly accelerated rectilinear motion. It takes 2.3 s for the stone to reach the water.

We can calculate the height of the bridge, which is equal to the displacement of the stone, using the following kinematic equation.

[tex]s = ut + \frac{1}{2} a t^{2} = (0m/s)(2.3 s) + \frac{1}{2} (9.8m/s^{2} ) (2.3s)^{2} = 26 m[/tex]

where,

s: displacementu: initial speed (0 m/s)t: timea: acceleration due to gravity (9.8 m/s²)

A stone dropped from a 26 m bridge, takes 2.3 s to reach the water.

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The drawing shows a 26.1-kg crate that is initially at rest. Note that the view is one looking down on the top of the crate. Two forces, and , are applied to the crate, and it begins to move. The coefficient of kinetic friction between the crate and the floor is k = 0.347. Determine the (a) magnitude and (b) direction (relative to the x axis) of the acceleration of the crate.

Answers

Answer:

(a). The magnitude of the acceleration of the crate is 1.44 m/s².

(b). The direction  of the crate is 34.60°.

Explanation:

Given that,

Mass of crate = 26.1 kg

Coefficient of kinetic friction = 0.347

We need to calculate the resultant force

Using figure

[tex]F'=\sqrt{(F_{x}+F_{z})^2+F_{y}^2}[/tex]

Put the value into the formula

[tex]F'=\sqrt{(88\cos{55}+54)^2+(88\sin 54)^2}[/tex]

[tex]F'=126.4\ N[/tex]

(a). We need to calculate the acceleration of the crate

Using formula of sum of force

[tex]\sum{F}=F'-\mu N[/tex]

[tex]ma_{total}=F'-\mu mg[/tex]

[tex]a_{total}=\dfrac{F'}{m}-\mu g[/tex]

Put the value into thr formula

[tex]a_{total}=\dfrac{126.4}{26.1}-0.347\times9.8[/tex]

[tex]a_{total}=1.44\ m/s^2[/tex]

(b). We need to calculate the direction

Using formula of the direction

[tex]\theta=\tan^{-1}(\dfrac{F_{y}}{F_{x}+F_{z}})[/tex]

Put the value into the formula

[tex]\theta=\tan^{-1}(\dfrac{88\sin55}{88\cos55+54})[/tex]

[tex]\theta=34.60^{\circ}[/tex]

Hence, (a). The magnitude of the acceleration of the crate is 1.44 m/s².

The direction  of the crate is 34.60°.

III.
Solve:
1. An elephant puts a force of 30000N on its four feet, which have a total area of
750cm. What is the pressure exerted by the elephant on the
ground?

please explain T-T ​

Answers

Pressure = force / area = 30000/0.0750 = 400 000 N/m^2

Who is Josh Gibson write a short paragraph 3-5 sentences

Answers

Answer:

Hope this helps

Explanation:

Josh Gibson, (born December 21, 1911, Buena Vista, Georgia, U.S.—died January 20, 1947, Pittsburgh, Pennsylvania), American professional baseball catcher who was one of the most prodigious home run hitters in the game’s history. Known as “the black Babe Ruth,” Gibson is considered to be the greatest player who never played in the major leagues, there being an unwritten rule (enforced until the year of his death) against hiring black ballplayers

A boy is going down a slide. As he reaches the bottom, friction causes him to slow down and stop. Which one of Newton's laws is this?
2nd law
3rd law
1st law
4th law

Answers

I think it’s the second law

The given condition satisfies the Newton's First Law of motion. Hence, option (C) is correct.

Given data:

A boy slides down and friction causes him to slow down and stop.

In the given problem, when boy was sliding down, then he was in the state of motion, such that the when the he reaches at the bottom of hill, the friction plays the role of external agent to stop its motion.

This shows that the first law of motion is clearly followed which says that, "If an object is in motion, then it will be in motion until and unless any external force is applied on it". This is also known as law of inertia.

Thus, we can conclude that the given condition satisfies the Newton's First Law of motion. Hence, option (C) is correct.

Learn more about the Newton's first law of motion here:

https://brainly.com/question/974124

5.Projectile motion is free fall with an initial horizontal velocity. True or false

Answers

Explanation:

One of the interesting things about projectile motion is that the horizontal motion is independent of the vertical motion. Recall that in freefall, an object continually experiences a downward acceleration of 9.80ms2 but has no horizontal acceleration.

A 5000 kg truck and a 1000 kg car are traveling at constant speeds when they collide. What is true about the forces and accelerations on each?

Answers

Impact of truck will be more because it has more weight and more inertia
And you can apply that all stuff you read from book
So yeah

Force is the physical action that can give acceleration to a body upon which it is applied

The true statements about the forces and accelerations of each when they collide are;

The force acting on the truck is equals the reactive force of the car The acceleration of the car is five times the acceleration of the truck

The reasons why the above statements are true are given as follows:

Known:

Mass of the truck, m₁ = 5,000 kg

Mass of the car, m₂ = 1,000 kg

Velocity of the truck = [tex]v_t[/tex]

Velocity of the car = [tex]v_c[/tex]

According to Newton's third law of motion, action and reaction are equal and opposite

The force applied by the truck, F = The reactive force by the car

Force, F = Mass, m × Acceleration, a

Let a₁ represent the acceleration of the truck and let a₂ represent the acceleration of the car, we have;

F = 5,000 × a₁ = 1,000 × a₂

[tex]a_2 = \dfrac{5,000 \ kg}{1,000 \ kg} \times a_1 = 5 \cdot a_1[/tex]

Therefore;

The acceleration (rate of change of velocity) of the car, a₂  due to the collision is five times the acceleration of the truck due to the collision

Learn more about the about force and acceleration here:

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An object is dropped from 20. meters above the moon. The acceleration due to gravity on the moon is 1.62 m/s^2
a. How long does it take for the object to impact the moon?
b. At what speed does it impact the moon?

Answers

Answer:

a. Approximately  3.21 seconds

b. Approximately  5.196 m/s

Explanation:

a. The height from which the object is dropped = 20 meters

The location of the occurrence = The moon

The acceleration due to gravity on the moon  = 1.62 m/s²

The time it took the object to to impact the moon is given by the equation of free fall as follows;

h = 1/2·a·t²

Where;

h =The height from which the object is allowed to freely fall = 20 meters

a = The acceleration due to gravity on the moon  = 1.62 m/s²

t = The time of motion of the object

Substituting the values, gives;

20 = 1/2 × 1.62 × t²

t² = 20/(1.2 × 1.62) ≈ 10.23 s²

t = √ 10.23 ≈ 3.21 s

The time in motion of the object before impact, t = 3.21 seconds

b. The final speed, v is given from the equation for speed under free fall, which is presented as follows;

v = u + a·t

Where

u = The initial vertical velocity = 0

Substituting the values gives;

v = 0 + 1.62 × 3.21 ≈ 5.196 m/s

The final speed, v with which the object impacts the moon ≈ 5.196 m/s

A car traveling 60 miles west (-) stops and then travels another 20 miles
west (-). The car then loops around and travels back to the east (+) a total
of 10 miles. What is the displacement of the car?*

Answers

Answer:

128

Explanation:

One clomiter is 1.06 multipled by 80

A water-balloon launcher with a mass of 2.0 kg is suspended on a wire. It
fires a 0.75 kg balloon to the west at a velocity of 14.0 m/s. What is the
resulting velocity of the launcher if the net force on the launcher is equal to
the reaction force?
A. 5.3 m/s east
B. 6.6 m/s west
C. 7.4 m/s east
D. 37.3 m/s east

Answers

Answer:

5.3

Explanation:

Answer:

5.3 m/s east

Explanation:

The cat quickly hopped from the floor onto the couch.
is an example of what? position, motion, speed, velocity or acceleration

Answers

Answer: Motion

Explanation:

Remi travels 160 meters in 4 seconds. What was Remi's initial speed if her final velocity was 6.9 m/s?

Answers

Answer:

73.1 m/s

Explanation:

Given:

Δx = 160 m

v = 6.9 m/s

t = 4 s

Find: v₀

Δx = ½ (v + v₀) t

160 m = ½ (6.9 m/s + v₀) (4 s)

v₀ = 73.1 m/s

The upward force on a car that is falling off a cliff is what?

a. air resistance
b. momentum
c. inertia
d. terminal velocity

Answers

Answer:

A. air resistance

Explanation:

I think so

An object falls from the Transco Tower in Houston and takes 15 seconds to reach the ground. How tall is the building:​

Answers

Answer: 1102.5 meters

Explanation:

whu is it important to mave regular supervision of weights and measurements in the market​

Answers

Answer:

Hope the answer helped you. if yes pls follow me

Explanation:

the fundamental answer is without regular supervision of definition of weights and measures,commerce exchange will be impossible and there would be no market whatsoever for anything.

Answer:

the fundamental answer is without regular supervision of definition of weights and measures,commerce exchange will be impossible and there would be no market whatsoever for anything.

Explanation:

"who"

PLEASE HELP ME FAST!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Answers

Answer:

Basketball has a mass of 0.1kg

m = 0.1 kg

The basket ball is moving at constant speed, this shows that it is not accelerating. So, acceleration is zero

a = 0m/s²

The constant speed is 6m/s

v = 6m/s

So, force to keep it moving with this constant speed can be calculated using Newton second law of motion

F = ma

F = m × 0

F = 0N

So, since the basket ball is moving at constant speed, then, the force need to keep the ball moving is 0N.

Which of the following individuals would be best classified as being in identity diffusion?
A.
Pauline isn’t interested in politics because she’d like to enjoy being a kid longer.
B.
Richard has decided to become a Democrat after much soul searching.
C.
Maria has adopted her parents’ identification as Protestant without considering other options.
D.
Pierce is trying many different identities but hasn’t decided on one yet.

Answers

Answer: C

Explanation: after reading it over and over shes the most reasonable. But I could be wrong so be cautious.

According to the question, Maria would be best classified as being in identity diffusion. So, option (C) is correct answer.

What is identity diffusion?

People who are experiencing identity diffusion haven't chosen an ideological or occupational route for the future and aren't making any effort to do so. Identity diffusion occurs during adolescence, a time when individuals are attempting to define their identities, but it can also last into adulthood.

When a person isn't actively forming an identity or committing to one, identity diffusion happens.Many people go through a phase of identity diffusion in their early years of adolescence or in childhood, which they eventually grow out of. Long-term identity diffusion is yet conceivable.James Marcia created four "identity statuses" in the 1960s, and identity diffusion is one of them. These identity statuses are a continuation of Erik Erikson's research on the formation of teenage identities.

In the question, Maria has adopted her parents’ identification as Protestant without considering other options. She   haven't chosen an ideological or occupational route for the future and aren't making any effort to do so.  So, Maria  would be best classified as being in identity diffusion.

To learn more about identity diffusion, refer the link:

https://brainly.com/question/4412284

#SPJ6

Which quantity is a vector?
displacement
distance

Answers

I think it’s displacement. May i please receive brainliest :)

When converting from smaller to larger units the decimal point travels right *

Answers

Answer:

False, it travels left.

Explanation:

Hello.

In this case, we can answer this with an example. If we have 200 g and we want that value in a larger unit, for instance, kilogram, the following conversion is performed since 1 kg equals 1000 g:

[tex]200g*\frac{1kg}{1000kg}=0.200g[/tex]

Whereas we needed to move the decimal point from right to left, which means that it travels left, that is why the statement is false.

Best regards.

19. Calculate the work done when a 30 N force pushes a rock 10 m. a) 3J b) 0.33 J c) 40 J d) 300 J

20. How far did a rock move if a force of 200 N moved it doing 100 J of work? a) 2 m b) 0.5 m c) 20,000 m d) 300 m

21. An explosion of gas from a Hawaiian volcano blows a rock into the sky. the rock has 2000J of kinetic energy. What was its mass if the rock had a velocity of 20m/s. a) 200Kg b) 20,000Kg c) 10Kg d) 200Kg

22. How much potential energy does a 2 kg book have if it is 2 meters from the ground? a) 39.2J b) 12 J c) 19.6 J d) 98 J

23. 45J of work were done on the object that moved 5M. How much force was applied to the object? a) 8N b) 9N c) 225N d) ON

24. If you do 40 joules of work lifting a 10N box, how high is the shelf you move it to. a) 400m b) 50m c) 40m d) 4m

25. A force of 100 newtons was necessary to lift a rock. A total of 150 joules of work was done. How far was the rock lifted? a) 1.5 m b) 15 m c) 0.15 m d) 150 m​

Answers

19. Calculate the work done when a 30 N force pushes a rock 10 m. a) 3J b) 0.33 J c) 40 J d) 300 J

20. How far did a rock move if a force of 200 N moved it doing 100 J of work? a) 2 m b) 0.5 m c) 20,000 m d) 300 m

21. An explosion of gas from a Hawaiian volcano blows a rock into the sky. the rock has 2000J of kinetic energy. What was its mass if the rock had a velocity of 20m/s. a) 200Kg b) 20,000Kg c) 10Kg d) 200Kg

22. How much potential energy does a 2 kg book have if it is 2 meters from the ground? a) 39.2J b) 12 J c) 19.6 J d) 98 J

23. 45J of work were done on the object that moved 5M. How much force was applied to the object? a) 8N b) 9N c) 225N d) ON

24. If you do 40 joules of work lifting a 10N box, how high is the shelf you move it to. a) 400m b) 50m c) 40m d) 4m

25. A force of 100 newtons was necessary to lift a rock. A total of 150 joules of work was done. How far was the rock lifted? a) 1.5 m b) 15 m c) 0.15 m d) 150 m19. Calculate the work done when a 30 N force pushes a rock 10 m. a) 3J b) 0.33 J c) 40 J d) 300 J

20. How far did a rock move if a force of 200 N moved it doing 100 J of work? a) 2 m b) 0.5 m c) 20,000 m d) 300 m

21. An explosion of gas from a Hawaiian volcano blows a rock into the sky. the rock has 2000J of kinetic energy. What was its mass if the rock had a velocity of 20m/s. a) 200Kg b) 20,000Kg c) 10Kg d) 200Kg

22. How much potential energy does a 2 kg book have if it is 2 meters from the ground? a) 39.2J b) 12 J c) 19.6 J d) 98 J

23. 45J of work were done on the object that moved 5M. How much force was applied to the object? a) 8N b) 9N c) 225N d) ON

24. If you do 40 joules of work lifting a 10N box, how high is the shelf you move it to. a) 400m b) 50m c) 40m d) 4m

25. A force of 100 newtons was necessary to lift a rock. A total of 150 joules of work was done. How far was the rock lifted? a) 1.5 m b) 15 m c) 0.15 m d) 150 m19. Calculate the work done when a 30 N force pushes a rock 10 m. a) 3J b) 0.33 J c) 40 J d) 300 J

20. How far did a rock move if a force of 200 N moved it doing 100 J of work? a) 2 m b) 0.5 m c) 20,000 m d) 300 m

21. An explosion of gas from a Hawaiian volcano blows a rock into the sky. the rock has 2000J of kinetic energy. What was its mass if the rock had a velocity of 20m/s. a) 200Kg b) 20,000Kg c) 10Kg d) 200Kg

22. How much potential energy does a 2 kg book have if it is 2 meters from the ground? a) 39.2J b) 12 J c) 19.6 J d) 98 J

23. 45J of work were done on the object that moved 5M. How much force was applied to the object? a) 8N b) 9N c) 225N d) ON

24. If you do 40 joules of work lifting a 10N box, how high is the shelf you move it to. a) 400m b) 50m c) 40m d) 4m

25. A force of 100 newtons was necessary to lift a rock. A total of 150 joules of work was done. How far was the rock lifted? a) 1.5 m b) 15 m c) 0.15 m d) 150 m

please mark me as brainliest.......

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When your blood pressure is low, choose a choice below that explains what occurs.
A. The nervous system signals smooth muscles in the blood vessels to relax to decrease blood pressure.
B. The nervous signals smooth muscles in the blood vessels to relax to increase blood pressure.
C. The nervous system signals smooth muscles to contract to decrease blood pressure.
D. The nervous system signals smooth muscles in the blood vessels to contract to increase blood pressure

Answers

Answer:

The correct option is;

D. The nervous system signals smooth muscles in the blood vessels to contract to increase blood pressure

Explanation:

The contraction or relaxation of the vascular smooth muscles lead to the blood vessel volume change and blood pressure change such that the blood is redirected to regions of the body that requires instantaneous increased oxygen intake. As such the nervous system signals the blood vessel's vascular smooth muscle to contract, through vasoconstriction so as to raise the blood pressure, when the blood pressure is low.

where is the image located when an objectis placed 30cm from a convex lens with a focal length of 10cm?​

Answers

Answer:

15 cm

Explanation:

using the thin lens formula for convex lens

                            [tex]\frac{1}{f} = \frac{1}{p} + \frac{1}{q}\\ \\where f = focal length \\ p = object distance \\ q = image distance\\[/tex]

 so,

         [tex]\frac{1}{q} = \frac{1}{f} - \frac{1}{p} \\\\\frac{1}{q} = \frac{1}{10} - \frac{1}{30} \\\frac{1}{q} = \frac{2}{30}\\\frac{1}{q} = \frac{1}{15cm}[/tex]

so,

    q = 15 cm

please type any energy transformation it will help a lot i would really appreciate it

prize: brainliest

Answers

Answer:

in electric lamp

Electric Energy to Heat and Light Energy

Explanation:

Answer:

Ex: an electric fan transforms electric energy to kinetic energy

Or

Chemical energy to heat and light energy

Explanation:

Hope this helps

a child riding a bicycle at 15 meters per second accelerates at -3,0 meters per second? for 4.0 seconds. What is the child's speed A at the end of this 4.0-second interval? (with work, all steps))

Answers

Answer:

27m/s

Explanation:

Given data

initital velocity u=15m/s

deceleration a=3m/s^2

time t= 4 seconds

final velocity v= ?

Applying the expression

v=u+at------1

substituting our data into the expression we have

v=15+3*4

v=15+12

v=27m/s

The velocity after 4 seconds is 27m/s

based on the information given, which part of inverstigation 2 is most likely the independent variable

Answers

Answer:

The independent variable is the variable that is changing.

Explanation:

I gave you this because you did not give us the work for use to see.

A gas is compressed to 75cm3 to a volume of 30cm3. Its temperature remains the same The pressure of the gas after it has been compressed is 110 Pa. What was the pressure before it was compressed?

Answers

Given parameters:

Initial volume  = 75cm³

New volume  = 30cm³

New pressure  = 110Pa

Unknown:

Initial pressure = ?

Solution:

Condition: temperature is constant

We simply apply Boyle's law to this problem:

   " the volume of a fixed mass(mole) of a gas varies inversely as the pressure changes if the temperature is constant".

  Mathematically;

          P₁ V₁  = P₂ V₂

where P and V are pressure and volume values

          1 and 2 are the initial and final states.

Input the parameters and solve for P₁;

     P₁ x 75  = 110 x 30

   P₁ = 44Pa

         

The initial pressure is 44Pa

The Earth’s ________________ on its ________ causes day and night.

Answers

Answer:

1. rotation. 2. axis

Explanation:

The Earths rotation on its axis causes day and night

A portable electric saw is used to cut through a wooden log. What happens to the pitch of the sound from the saw as the blade cuts farther into the log? Why?

Answers

The pitch increases as you cut into the wood. This is is due to the amount of wood being made to vibrate by the saw getting progressively slightly smaller and smaller.

Dos masas de 8kg es tan unidas en el extremo de una varilla de aluminio de 400mm de longitud. La varilla está sostenida en su parte media hora en círculos y solo puede soportar una tensión máxima de 800 N ¿cuál es la frecuencia máxima de revolución

Answers

Answer:

The maximum frequency of revolution is 3.6 Hz.

Explanation:

Given that,

Mass = 8 kg

Distance = 400 mm

Tension = 800 N

We need to calculate the velocity

Using centripetal force

[tex]F=\dfrac{mv^2}{r}[/tex]

Where, F= tension

m = mass

v= velocity

r = radius of circle

Put the value into the formula

[tex]800=\dfrac{8\times v^2}{200\times10^{-3}}[/tex]

[tex]v^2=\sqrt{\dfrac{800\times200\times10^{-3}}{8}}[/tex]

[tex]v=4.47\ m/s[/tex]

We need to calculate the maximum frequency of revolution

Using formula of frequency

[tex]f=\dfrac{v}{2\pi r}[/tex]

Put the value into the formula

[tex]f=\dfrac{4.47}{2\pi\times200\times10^{-3}}[/tex]

[tex]f=3.6\ Hz[/tex]

Hence, The maximum frequency of revolution is 3.6 Hz.

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