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3 years ago

7

An ambulance is currently traveling at 15m/s, and is accelerating with a constant acceleration of 5 m/s^2. The ambulance is atte

mpting to pass a car that is moving at a constant velocity of 30m/s. How far must the ambulance travel until it matches the car’s velocity?

1 answer:

Lorico [155]3 years ago

5 0

initial velocity=15m/s=u
Acceleration=a=5m/s^2
Final velocity=v=30m/s
Distance be s

Using 3rd equation of kinematics

$\\ \rm\longmapsto v^2-u^2=2as$

$\\ \rm\longmapsto s=\dfrac{v^2-u^2}{2a}$

$\\ \rm\longmapsto s=\dfrac{30^2-15^2}{2(5)}$

$\\ \rm\longmapsto s=\dfrac{900-225}{10}$

$\\ \rm\longmapsto s=\dfrac{675}{10}$

$\\ \rm\longmapsto s=67.5m$

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Which choice defines AC and DC correctly?

Aleks [24]

Answer: Option (B) is the correct answer.

Explanation:

Direct current is a current which flows in one direction, that is, flow of electrons is only in one direction.

Whereas alternate current is a current which reverses periodically, that is, there will be change in direction of electrons after a period of time.

Thus, we can conclude that the statement, In DC, electrons move in only one direction. In AC, electrons move in one direction and then in the other direction defines AC and DC correctly.

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4 years ago

Read 2 more answers

A block of wood of mass 24 kg floats on water. The volume of the block below the surface of the water and the density of the woo

Slav-nsk [51]

Answer:

0.024m^3

Explanation:

=======

Answer:

=======

Given:-

Mass of the block of wood = 24 kg

Volume of wood = 0.032 m^3

Density of water = 1000kg/m^3

Now,

Density of wood is given by,

\frac{m}{v} = \frac{24}{0.032} \\

\frac{m}{v} = 750 \: kg/m ^{3}

Therefore,

The density of wood is 750kg/m^3

By principle of floatation,

Mass \:of\: wood = Mass\: of\: liquid \:displaced

Therefore,

Mass of liquid displaced = 24kg

Volume of liquid displaced (v),

\frac{m}{v} = \frac{24}{1000} \\

\frac{m}{v} = 0.24m ^{3}

Now,

Since the volume of the wood is equal to the volume of water displaced, it is 0.024m^3

=====

Note:

=====

=> The volume of the wood below the water surface is the volume of water displaced.

=> Buoyant\: force = Weight\: of\: the \:displaced\: water.

8 0

3 years ago

5. George walks to a friend's house. He walks 750 meters North, then realizes he walked too far.

dedylja [7]

Answer:

Average speed: approximately $76.9\; {\rm m\cdot s^{-1}}$ .

Average velocity: approximately $38.5\; {\rm m \cdot s^{-1}}$ (to the north.)

Explanation:

Consider an object that travelled along a certain path. Distance travelled would be equal to the length of the entire path.

In contrast, the magnitude of displacement is equal to distance between where the object started and where it stopped.

In this question, the path George took required him to travel $750\; {\rm m} + 250\; {\rm m} = 1000\; {\rm m}$ in total. Hence, the distance George travelled would be $1000\; {\rm m}$ . However, since George stopped at a point $(750\; {\rm m} - 250\; {\rm m}) = 500\; {\rm m}$ to the north of where he started, his displacement would be only $500\; {\rm m}$ to the north.

Divide total distance by total time to find the average speed.

Divide total displacement by total time to find average velocity.

The total time of travel in this question is $13\; {\rm s}$ .. Therefore:

$\begin{aligned}\text{average speed} &= \frac{\text{total distance}}{\text{total time}} \\ &= \frac{1000\; {\rm m}}{13\; {\rm s}} \\ &\approx 76.9\; {\rm m\cdot s^{-1}}\end{aligned}$ .

$\begin{aligned}\text{average velocity} &= \frac{\text{total displacement}}{\text{total time}} \\ &= \frac{500\; {\rm m}}{13\; {\rm s}} && \genfrac{}{}{0px}{}{(\text{to the north})}{}\\ &\approx 38.5\; {\rm m\cdot s^{-1}} && (\text{to the north})\end{aligned}$ .

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2 years ago

If the center of mass passes outside the area of support of an object, what will happen to it?

defon

Answer:

If a vertical line extending down from an object's CG extends outside its area of support, the object will topple

Explanation:

We can understand better this situation using a diagram with the forces acting on it.

In the attached image we can see that when the gravity center is bouncing outside from the area of the pedestal, the object will be out of balance and will fall.

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3 years ago

400 gallons of pesticide is accidentally spilled into a lake and uniformly mixes with the water. The volume of the lake includin

svet-max [94.6K]

Answer:

t=27725.8minutes

Explanation:

To determinate use the law the change of volume in determinate time is derivate so:

$\frac{dV}{dt}=flowin-flowout$

The flow in is zero and the flow out is modeling with V as the volume out in the volume of the lake in the reason of change.

$\frac{dV}{dt}=0-(\frac{V}{10x10^{8}})*5000\\\frac{dV}{dt}=-5x10^{-5}*V \\dV*V=-5x10^{-5}*dt$

Integrate to get the volume function

$\int\limits{\frac{1}{V}}\, dv=\int\limits{-5x10^{-5} }\, dt\\ ln(V)=-5x10^{-5}*t\\ln*e(V)=C*e^{-5x10^{-5}*t}\\$

The find the constant C in the time t=0 the volume is knowing so:

$t=0s\\V=400\\V=C*e^{0}\\C=400$

$V=400*e^{-5x10^{-5}*t}$

The volume is 1 part per million so:

$\frac{V}{10x^{8}}=\frac{1}{10x^{6}}\\ V=100$

$V=400*e^{-5x10^{-5}*t}\\100=400*e^{-5x10^{-5}*t}\\\frac{100}{400}=e^{-5x10^{-5}*t}\\ln*\frac{1}{4}=ln*e^{-5x10^{-5}*t}\\-ln(4)=-5x10^{-5}*t\\ t=\frac{-ln(4)}{-5x10^{-5}}=27725.88\\t=27725.8minutes$

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3 years ago