1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
Maru [420]
3 years ago
5

uring the investigation of a traffic accident, police find skid marks 89.9 m long. They determine the coefficient of friction be

tween the car's tires and the roadway to be 0.500 for the prevailing conditions. Estimate the speed of the car when the brakes were applied.
Physics
1 answer:
aivan3 [116]3 years ago
4 0

Answer:

V_{0}=29.68m/s

Explanation:

In order to solve this problem, we must first do a drawing of the situation (see attached picture).

When the brakes of the car were applied, we can see that there was only one horizontal force affecting the vehicle's movement, which was the force of friction. When analyzing the free body diagram we can apply Newton's laws to determine the equations we will use to solve this.

\sum F_{x}=ma

so:

-f=ma

we also know that:

f=N\mu_{k}

so

-N\mu_{k}=ma

we can now solve for the acceleration, so we get:

a=\frac{-N\mu_{k}}{m}

we don't know what the normal force is, so we can find it out by analyzing the vertical forces applied to the car:

\sum F_{y}=0

so we get:

N-W=0

which means that:

N=W

we also know that:

W=mg

so

N=mg

we can substitute this into the first equation so we get:

a=\frac{-mg\mu_{k}}{m}

which simplifies to:

a=-g\mu_{k}

we can now substitute the provided data:

a=(-9.8m/s^{2})(0.5)

which yields:

a=-4.9m/s^{2}

once we got the acceleration, we can use kinematics formulas to solve this, we got the following formula:

a=\frac{V_{f}^{2}-V_{0}^{2}}{2x}

we know the final velocity must be zero, since that's where the car got to a stop, so the formula then becomes:

a=-\frac{V_{0}^{2}}{2x}

we can now solve for the initial velocity, which yields:

V_{0}=\sqrt{-2xa}

so we can now substitute the daa we know, so we get:

V_{0}=\sqrt{-2(89.9m)(-4.9m/s^{2})}

so we get:

V_{0}=29.68m/s

So from this we know that the velocity of the car must have been of at least 29.68m/s when the brakes were applied.

You might be interested in
Consider a container of oxygen gas at a temperature of 23°C that is 1.00 m tall. Compare the gravitational potential energy of a
Sergio039 [100]

Answer:

Yes, it is reasonable to neglect it.

Explanation:

Hello,

In this case, a single molecule of oxygen weights 32 g (diatomic oxygen) thus, the mass of kilograms is (consider Avogadro's number):

m=1molec*\frac{1mol}{6.022x10^{23}molec} *\frac{32g}{1mol}*\frac{1kg}{1000g}=5.31x10^{-26}kg

After that, we compute the potential energy 1.00 m above the reference point:

U=mhg=5.31x10^{-26}kg*1.00m*9.8\frac{m}{s^2}=5.2x10^{-25}J

Then, we compute the average kinetic energy at the specified temperature:

K=\frac{3}{2}\frac{R}{Na}T

Whereas N_A stands for the Avogadro's number for which we have:

K=\frac{3}{2} \frac{8.314\frac{J}{mol*K}}{6.022x10^{23}/mol}*(23+273)K\\ \\K=6.13x10^{-21}J

In such a way, since the average kinetic energy energy is about 12000 times higher than the potential energy, it turns out reasonable to neglect the potential energy.

Regards.

8 0
3 years ago
A bodybuilder deadlifts a 215 kg weight to a height of 0.90 m above the ground. If he deadlifts this weight 10 times in a span o
wariber [46]

A bodybuilder deadlifts 215 kg to a height of 0.90 m. If he deadlifts this weight 10 times in 45 s, the power exerted is 421 W (b.)

<h3>What is power?</h3>

In physics, power (P) is the work (W) done over a period of time.

  • Step 1. Calculate the work done by the bodybuilder each time.

The bodybuilder lifts a 215 kg (m) weight to a height of 0.90 m (h). Being the gravity (g) of 9.81 m/s², we can calculate the work done in each lift using the following expression.

W = m × g × h = 215 kg × 9.81 m/s² × 0.90 m = 1.9 × 10³ N

  • Step 2. Calculate the work done by the bodybuilder over 10 times.

W = 10 × 1.9 × 10³ N = 1.9 × 10⁴ N

  • Step 3. Calculate the power exerted by the bodybuilder.

The bodybuilder does a work of 1.9 × 10⁴ N in a 45-s span.

P = 1.9 × 10⁴ N/45 s = 421 W

A bodybuilder deadlifts 215 kg to a height of 0.90 m. If he deadlifts this weight 10 times in 45 s, the power exerted is 421 W (b.)

Learn more about power here: brainly.com/question/911620

#SPJ1

4 0
1 year ago
aman E. Describe the important discovery that Galileo made about falling objects when he performed the experiment illustrated in
Marta_Voda [28]

Answer:

Hey

(note you have forgotten your diagram so this may not be what you where hoping for.)

The important discovery that galilao made was that he proved that <em><u>all objects no matter their mass fall at the same rate.</u></em>

That is to say that a bowling ball falls at the same rate as a truck.

4 0
3 years ago
M=20kg F=10N d=25m<br>Work done=?​
fomenos

w=f×d

w=10N×25m

w=250Nm

5 0
2 years ago
A unit of power equal to 746 watts is a
NemiM [27]
≈ 746 watts is a 1 Horsepower, because that's in the SI base unit. 
4 0
3 years ago
Other questions:
  • 4.5 billion km, the average separation between the sun and Neptune (report answer in hours). How long does it take light to trav
    15·1 answer
  • A sled is on an icy (frictionless) slope that is 30° above the horizontal. When a 40-N force, parallel to the incline and direct
    10·1 answer
  • 1. On which date does the Antarctic Circle have 24 hours of daylight? A. June 21
    8·2 answers
  • Four identical masses of 2.5 kg each are located at the corners of a square with 1.0-m sides. What is the net force on any one o
    7·1 answer
  • PLEASE HELP! Explain how energy travels outward from the core and is emitted from the Sun. Include what happens in each layer of
    12·2 answers
  • An object mass 5kg, moving at a velocity of 10metre per seconds is suddenly heat by a force of 2N for a time 3sec. Find its new
    8·1 answer
  • which of these rocks are formed by volcanic activity? select the two correct answers. a. limestone b. granite c. marble d. basal
    5·2 answers
  • - Which of the following does not move as a transverse wave?
    13·1 answer
  • A net force of 15 N is applied to a cart with a mass of 2.1 kg. What is the acceleration of the cart?
    13·1 answer
  • If you stretch a rubber hose and pluck it, you can observe a pulse traveling up and down the hose.(i) What happens to the speed
    6·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!