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3 years ago

12

A driver traveling at 30.0 m/s presses the brakes decelerates at -8.80 m/s^2. How much time, in second, does it take her to come

to a full stop?

1 answer:

Kruka [31]3 years ago

4 0

Answer:

It takes her 3.409 seconds to make a full stop.

Explanation:

The time it takes to make a full stop can be determined by the equation of velocity for a Uniformly Accelerated Rectilinear Motion:

$v_{f} = v_{i} + at$ (1)

Where $v_{f}$ is the final velocity, $v_{i}$ is the initial velocity, a is the acceleration and t is the time.

Equation (1) can be rewritten in terms of t:

$v_{f} - v_{i} = at$

$t = \frac{v_{f} - v_{i}}{a}$ (2)

For this particular case the final velocity will be equal to zero ( $v_{f} = 0$ ):

$t = \frac{0 m/s - 30.0 m/s}{-8.80 m/s^{2}}$

$t = 3.409 s$

So it takes her 3.409 seconds to make a full stop.

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Equations to use: v= λ ∙ f v=d/t

Margarita [4]

b. 460.8 m/s

Explanation:

The relationship between the speed of the wave along the string, the length of the string and the frequency of the note is

$f=\frac{v}{2L}$

where v is the speed of the wave, L is the length of the string and f is the frequency. Re-arranging the equation and substituting the data of the problem (L=0.90 m and f=256 Hz), we can find v:

$v=2Lf=2(0.90 m)(256 Hz)=460.8 m/s$

c. 18,000 m

Explanation:

The relationship between speed of the wave, distance travelled and time taken is

$v=\frac{d}{t}$

where

v = 6,000 m/s is the speed of the wave

d = ? is the distance travelled

t = 3 s is the time taken

Re-arranging the formula and substituting the numbers into it, we find:

$d=vt=(6,000 m/s)(3 s)=18,000 m$

3 0

3 years ago

A train starts at rest in a station and accelerates at a constant 0.987 m/s2 for 182 seconds. Then the train decelerates at a co

algol [13]

Answer:

$\displaystyle X_T=66.6\ km$

Explanation:

<u>Accelerated Motion </u>

When a body changes its speed at a constant rate, i.e. same changes take same times, then it has a constant acceleration. The acceleration can be positive or negative. In the first case, the speed increases, and in the second time, the speed lowers until it eventually stops. The equation for the speed vf at any time t is given by

$\displaystyle V_f=V_o+a\ t$

where a is the acceleration, and vo is the initial speed .

The train has two different types of motion. It first starts from rest and has a constant acceleration of $0.987 m/s^2$ for 182 seconds. Then it brakes with a constant acceleration of $-0.321 m/s^2$ until it comes to a stop. We need to find the total distance traveled.

The equation for the distance is

$\displaystyle X=V_o\ t+\frac{a\ t^2}{2}$

Our data is

$\displaystyle V_o=0,a=0.987m/s^2,\ t=182\ sec$

Let's compute the first distance X1

$\displaystyle X_1=0+\frac{0.987\times 182^2}{2}$

$\displaystyle X_1=16,346.7\ m$

Now, we find the speed at the end of the first period of time

$\displaystyle V_{f1}=0+0.987\times 182$

$\displaystyle V_{f1}=179.6\ m/s$

That is the speed the train is at the moment it starts to brake. We need to compute the time needed to stop the train, that is, to make vf=0

$\displaystyle V_o=179.6,a=-0.321\ m/s^2\ ,V_f=0$

$\displaystyle t=\frac{v_f-v_o}{a}=\frac{0-179.6}{-0.321}$

$\displaystyle t=559.5\ sec$

Computing the second distance

$\displaystyle X_2=179.6\times559.5\ \frac{-0.321\times 559.5^2}{2}$

$\displaystyle X_2=50,243.2\ m$

The total distance is

$\displaystyle X_t=x_1+x_2=16,346.7+50,243.2$

$\displaystyle X_t=66,589.9\ m$

$\displaystyle \boxed{X_T=66.6\ km}$

8 0

3 years ago

Diesel fuel is used in the engine of trucks that carry dirt fruit and other cargo. Fuel is burned in engines to make the motor m

Marina86 [1]

Answer: Fuel is burned in engines to make the motor move.

( Chemical to Mechanical )

Explanation:

during combustion of the diesel ( when the fuel is burnt in the engine of the vehicle, the diesel ( chemical energy ) is transformed or converted to Mechanical energy. This mechanical energy is what the truck uses in moving. Without the combustion of the fuel the vehicle won’t move and the combustion of diesel is achieved through compression unlike that of fuel.

4 0

3 years ago

Three people pull simultaneously on a stubborn donkey. Jack pulls directly ahead of the donkey with a force of 77.3 N, Jill pull

DiKsa [7]

Answer:

$F_{net} = 232.8 N$

towards right so it is -15 degree

Explanation:

Net force in forward direction due to all three is given as

$F_x = F_1 + F_2cos45 + F_3cos45$

here we know that

$F_1 = 77.3 N$

$F_2 = 61.7 N$

$F_3 = 147 N$

$F_x = 77.3 + 61.7 cos45 + 147 cos45$

$F_x = 224.9 N$

Similarly in Y direction we will have

$F_y = F_3 sin45 - F_2 sin45$

$F_y = (147 - 61.7)sin45$

$F_y = 60.3 N$

Now the net force on the donkey is given as

$F_{net} = \sqrt{F_x^2 + F_y^2}$

$F_{net} = \sqrt{224.9^2 + 60.3^2}$

$F_{net} = 232.8 N$

Now direction of force is given as

$tan\theta = \frac{F_y}{F_x}$

$tan\theta = \frac{60.3}{224.9}$

$\theta = 15^o$ towards right so it is -15 degree

3 0

3 years ago

You're collecting data in BeyondLabz for an object in free fall, subject to air resistance. How do you know when you've collecte

denis23 [38]

Enough data points would have been collected when specific data for upward and downward motion are collected.

<h3>What is a Data point?</h3>

A data point is a discrete unit of information. This information is always unique.

<h3>Free fall</h3>

An object subjected to free fall is under the influence of gravity. An object subjected has different time of motion for upward and downward motion.

Thus, we can conclude that enough data points would have been collected when specific data for upward and downward motion are collected.

Learn more about free fall here: brainly.com/question/10909077

6 0

2 years ago