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
Usimov [2.4K]
2 years ago
14

By what percent does the braking distance of a car decrease, when the speed of the car is reduced by 10.3 percent? Braking dista

nce is the distance a car travels from the point when the brakes are applied to when the car comes to a complete stop.
Physics
1 answer:
likoan [24]2 years ago
6 0

The braking distance is the distance traveled by a car experiencing a braking force until it comes to rest.

Our initial energy is solely kinetic:
E_i = \frac{1}{2}mv^2

And, since the car goes to rest, it is no longer in motion. It will have no kinetic energy.
E_f = 0

Therefore, there was work done by the braking force.

W_B = E_f - E_i = -\frac{1}{2}mv^2

Recall the definition of work:
W = F\cdot \Delta x

Or in this case, since the displacement and breaking force are antiparallel:
W = -F_B\Delta x

This is equivalent to the dissipation of kinetic energy:
W = -F_B\Delta x = -\frac{1}{2}mv^2

Now, to visualize this, let's rearrange the equation to solve for displacement.

\Delta x =\frac{mv^2}{2F_B}

<u>There is a direct, SQUARE relationship between necessary braking distance speed. </u>

If the speed was reduced by 10.3 percent, its new speed is only 89.7% percent of the original, so:
\Delta x' =\frac{m(0.897v)^2}{2F_B}

\Delta x' = 0.8046\Delta x

The reduction by a percentage is:
1 - 0.8046 = 0.1954 \\\\\boxed{= 19.54\%}

You might be interested in
In a coiled spring, the particles of the medium vibrate to and fro about their
Kitty [74]

Answer:

In a coiled spring, the particles of the medium vibrate to and fro about their mean positions at an angle of

A. 0° to the direction of propagation of wave

Explanation:

The waveform of a coiled spring is a longitudinal wave, which is made up of vibrations of the spring which are in the same direction as the direction of the wave's advancement

As the coiled spring experiences a compression force and is then released, it experiences a sequential movement of the wave of the compression that extends the length of the coiled spring which is then followed by a stretched section of the coiled spring in a repeatedly such that the direction of vibration of particles of the coiled is parallel to direction of motion of the wave

From which we have that the angle between the direction of vibration of the particles of the coiled spring and the direction of propagation of the wave is 0°.

8 0
2 years ago
What is the escape speed of an electron launched from the surface of a 1.1-cm-diameter glass sphere that has been charged to 8.0
zimovet [89]
At surface,
v = kq/r

And potential energy of an electron is given by,
PE = -ev = -ekq/r

At escape velocity,
PE + KE = 0.
Therefore,
1/2mv^2 - ekq/r =0
1/2mv^2 = ekq/r
v = Sqrt [2ekq/mr], where v = escape velocity, e = 1.6*10^-19 C, k = 8.99*10^9 Nm^2/C^2, m = 9.11*10^-31 kg, r = 1.1*10^-2 m, q = 8*10^-9 C

Substituting;
v = Sqrt [(2*1.6*19^-19*8.99*10^9*8*10^-9)/(9.11*10^-31*1.1*10^-2)] = 47949357.23 m/s ≈ 4.795 *10^7 m/s
5 0
3 years ago
A body of mass 2 kg is moving in the positive X-Direction with a speed of 4 m/s collides head on with an another body of mass 3
Inga [223]
m_1=2 \\ m_2=3 \\ v_1=4 \\ v_2=1 \\ v\text{ =speed after collision (to be determined)}.

The momentul of the system preserves:

m_1v_1-m_2v_2=(m_1+m_2)v \ \ \ \ \ \Rightarrow \ \ \ \ \ v=\dfrac{m_1v_1-m_2v_2}{m_1+m_2}.

Ok, we found the speed after the collision.
Now, because the impact is plastic, it produces heat, sound energy and who knows what other forms of energy. We denote all this wasted energy with E.

Now, we write the energy conservation law:

\dfrac{m_1v_1^2}{2}+\dfrac{m_2v^2_2}{2}=\dfrac{(m_1+m_2)v^2}{2}+E

From the above equation, you find E,  and then conclude that the sound energy can certainly not be greater than this.
8 0
3 years ago
2. What is the speed of section A? Section B? Section C?
Nutka1998 [239]
Im pretty sure A-10 b-0 c-40
8 0
3 years ago
What are the possible effects of global warming?
11Alexandr11 [23.1K]
A possible effect is the risk of Icecaps melted
6 0
3 years ago
Other questions:
  • A ball is tossed straight up from the surface of a small, spherical asteroid with no atmosphere. The ball rises to a height equa
    15·2 answers
  • An organism that breaks down other living things when they die
    14·1 answer
  • Four identical particles of mass 0.980 kg each are placed at the vertices of a 4.14 m x 4.14 m square and held there by four mas
    5·1 answer
  • A person kicks a ball, giving it an initial velocity of 20.0 m/s up a wooden ramp. When the ball reaches the top, it becomes air
    6·1 answer
  • A ski gondola is connected to the top of a hill by a steel cable of length 620 m and diameter 1.5 cm. As the gondola comes to th
    11·1 answer
  • If your friend said that to that kinetic energy was changing to potential emergy at point c, how would you respond
    5·1 answer
  • Friction exists only when two objects rub against each other.<br> A.True<br> B.False
    14·2 answers
  • List the three main things necessary to build an electromagnet.
    15·1 answer
  • If a roller coaster has 50,000 J of potential energy at the top of the first hill, how much kinetic energy does it have at the l
    13·1 answer
  • 3. A Gas has a volume of 35 Liters at 10 atm pressure. To expand the volume to 80 Liters, what will the pressure be?
    9·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!