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ivolga24 [154]
2 years ago
12

This question is typical on some driver license exams: A car moving at 43 km/h skids 17 m with locked brakes. How far will the c

ar skid with locked brakes at 129 km/h? Assume that energy loss is due only to sliding friction.
Answer in units of m.
Physics
1 answer:
3241004551 [841]2 years ago
4 0

The new stopping distance is 152.6 m

Explanation:

The motion of the car is a uniformly accelerated motion, so we can use the following SUVAT equation:

v^2-u^2=2as

where in the initial situation, we have:

v = 0 is the final velocity of the car

u = 43 km/h = 11.9 m/s is the initial velocity

s = 17 m is the stopping distance

a is the acceleration

Solving for a, we find the acceleration:

a=\frac{v^2-u^2}{2s}=\frac{0-(11.9)^2}{2(17)}=-4.2 m/s^2

The acceleration depends only on the sliding friction: this means that it is constant also in the second situation, where we have

u = 129 km/h = 35.8 m/s

So we can use the same equation again to find s, the new stopping distance:

s=\frac{v^2-u^2}{2a}=\frac{0-(35.8)^2}{2(-4.2)}=152.6 m

Learn more about accelerated motion:

brainly.com/question/9527152

brainly.com/question/11181826

brainly.com/question/2506873

brainly.com/question/2562700

#LearnwithBrainly

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You throw a ball upward with an initial speed of 4.3 m/s. When it returns to your hand 0.88 s later, it has the same speed in th
djverab [1.8K]

Answer:

The acceleration is -9.8 m/s²

Explanation:

Hi there!!

When you throw a ball upward, there is a downward acceleration that makes the ball return to your hand. This acceleration is produced by gravity.

The average acceleration is calculated as the variation of the speed over time. In this case, we know the time and the initial and final speed. Then:

acceleration = final speed - initial speed/ elapsed time

acceleration = -4.3 m/s - 4.3 m/s / 0.88 s

acceleration = -9.8 m/s²  

4 0
2 years ago
Two people push on the same door from opposite sides as shown.
tangare [24]
The correct answer is
<span>c. one person exerts more force than the other so that the forces are unbalanced.

In fact, the door is initially at rest. In order to move the door, a net force different from zero should be applied, according to Newton's second law:
</span>\sum F = ma
<span>where the term on the left is the resultant of the forces acting on the door, m is the door mass and a its acceleration.

In order to move the door, the acceleration must be different from zero. But this means that the resultant of the forces acting on it must be different from zero: this is possible only if  the forces applied by the two persons are unbalanced, i.e. one person exerts more force than the other.</span>
3 0
2 years ago
Read 2 more answers
In a particular experiment to study the photoelectric effect, the frequency of the incident light and the temperature of the met
qwelly [4]

Answer:

B. The number of electrons emitted from the metal per second increases.

Explanation:

Light consists of photons . Energy of each photon depends upon frequency of light . The increase in intensity increases the number of photons . It does not increase energy of photons .

So if a high intensity light falls on a photosensitive plate , each photon ejects one electron . So number of electrons increases if we increase intensity of photon. It does not increase kinetic energy of ejected electrons . Work function depends upon the nature of plate.

6 0
2 years ago
what should be done in order to increase the gravitational force between two objects? Decrease the mass of both of the objects.
sesenic [268]

Answer:

Decrease the distance between the two objects.

Explanation:

The force (F) of attraction between two masses (M₁ and M₂) separated by a distance (r) is given by:

F = GM₁M₂ / r²

NOTE: G is the gravitational force constant.

From the equation:

F = GM₁M₂ / r²

We can say that the force is directly proportional to the masses of the object and inversely proportional to the square of the distance between them. This implies that an increase in any of the masses will increase the force of attraction and likewise, a decrease in any of the masses will lead to a decrease in the force of attraction.

Also, an increase in the distance between the masses will result in a decrease in the force of attraction and a decrease in the distance between the masses, will result in an increase in the force of attraction.

Considering the question given above,

To increase the gravitational force between the two objects, we must decrease the distance between the two objects as explained above.

8 0
3 years ago
The force between a pair of charges is 900 newtons. The distance between the charges is 0.01 meters. If one of the charges is 2e
Maksim231197 [3]

Answer:

\fbox{strength  \: of \:  the \:  other \:  charge  =  - 0.0196 Ke \: Coulomb}

Explanation:

Given:

Force between pair of charges= 900 newtons

The distance between the charges = 0.01 meters

Strength of Charge first q1 = 2e-10 Coulomb

To find:

Strength of Charge second q2 = ____ Coulomb?

Solution:

We know that,

Force between two charges separate by distance r is given by the equation,

|F| =  K_e \frac{q1 \cdot \: q2}{ {r}^{2} }  \\ 900 =K_e  \frac{(2e - 10)\cdot \: q2}{ {0.01}^{2} } \\ 900 \times  {10}^{ - 4}  =  K_e {(2e - 10)\cdot \: q2} \\ q2 =   \frac{9 \times  {10}^{ - 2} }{(2e - 10) K_e}  \\  \\  \fbox{We \:  know \:  that \:  e = 2.71 } \\  substituting \: the \: value \: \\ q2 =  \frac{9 \times  {10}^{ - 2} }{(2 \times 2.71 - 10)K_e}  \\ q2 =  \frac{0.09}{ - 4.58 K_e}  \\ q2 =  \frac{-0.0196}{K_e}\: coulomb

\fbox{strength  \: of \:  the \:  other \:  charge  =  - 0.0196 Ke \: Coulomb}

<em><u>Thanks for joining brainly community!</u></em>

3 0
2 years ago
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