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3 years ago

A truck brakes from 15 m/s to 2 m/s in 15 seconds. What is its acceleration?

1 answer:

3 0

If we take v=u+at and our given values are:

v=final velocity 20m/s

u=initial velocity 15m/s

a=acceleration

t=time 5sec

we plug those into our equation:

20m/s=15m/s+a(5s)

now we just rearrange to solve for acceleration.

(5m/s)/(5s)=a

a=1m/s^2

hope this helps!
PLEASE MARK BRAINLEIST

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A force of 7.0 N acts on a block of wood at an angle of 50 degrees above the horizontal as the block moves a distance of 6.4 met

Aneli [31]

Answer:

28.796 J

Explanation:

I hope that it's a correct answer.

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3 years ago

You are making cookies that call for 3 tablespoons of molasses, but you are having trouble measuring out the thick, syrupy liqui

Andreyy89

You could heat the syrup, grease the spoon with shortening, because if you do, then the molasses won't stick when you pour it out of the spoon into the batter.

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3 years ago

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Mark creates a graphic organizer to review his notes about electrical force. Which labels belong in the regions marked X and Y?

sveta [45]

Answer:

The correct answer is A

Explanation:

The question requires as well the attached image, so please see that below.

Coulomb's Law.

The electrical force can be understood by remembering Coulomb's Law, that describes the electrostatic force between two charged particles. If the particles have charges $q_1$ and $q_2$ , are separated by a distance r and are at rest relative to each other, then its electrostatic force magnitude on particle 1 due particle 2 is given by:

$|F|=k \cfrac{q_1 q_2}{r^2}$

Thus if we decrease the distance by half we have

$r_1 =\cfrac r2$

So we get

$|F|=k \cfrac{q_1 q_2}{r_1^2}$

Replacing we get

$|F|=k \cfrac{q_1 q_2}{(r/2)^2}\\|F|=k \cfrac{q_1 q_2}{r^2/4}$

We can then multiply both numerator and denominator by 4 to get

$|F|=k \cfrac{4q_1 q_2}{r^2}$

So we have

$|F|=4 \left(k \cfrac{q_1 q_2}{r^2}\right)$

Thus if we decrease the distance by half we get four times the force.

Then we can replace the second condition

$q_{2new} =2q_2$

So we get

$|F|=k \cfrac{q_1 q_{2new}}{r_1^2}$

which give us

$|F|=k \cfrac{q_1 2q_2}{r_1^2}\\|F|=2\left(k \cfrac{q_1 q_2}{r_1^2}\right)$

Thus doubling one of the charges doubles the force.

So the answer is A.

8 0

3 years ago

Read 2 more answers

A reciprocating compressor is a device that compresses air by a back-and-forth straight-line motion, like a piston in a cylinder

QveST [7]

Answer:

$\Delta \theta = 47.57^{\circ} C$

Explanation:

given,

moles of air compressed, n = 1.70 mol

initial temperature, T₁ = 390 K

Power supply by the compressor, P = 7.5 kW

Heat removed = 1.3 kW

Angular frequency of the compressor, f = 110 rpm = 110/60 = 1.833 rps.

Time of compression = time of the hay revolution

= $\dfrac{1}{2}\ T$

= $\dfrac{1}{2}\times \dfrac{1}{f}$

= $\dfrac{1}{2}\times \dfrac{1}{1.833}$

=0.273 s

Using first law of thermodynamics

U = Q - W

now,

$\dfrac{\Delta U}{\Delta t} = \dfrac{\Delta Q}{\Delta t}- \dfrac{\Delta W}{\Delta t}$

Power supplied $\dfrac{\Delta W}{\Delta t}$ = 7.5 kW

heat removed $\dfrac{\Delta Q}{\Delta t}$ = 1.3 kW

now,

$\dfrac{\Delta U}{\Delta t} = 7.5 -1.3$

$\dfrac{\Delta U}{\Delta t} = 6.2 kW$

we know,

$\dfrac{\Delta U}{\Delta t}=\dfrac{nC_v\Delta \theta}{\Delta t}$

C_v for air = 5 cal/° mol

= 5 x 4.186 J/mol°C = 20.93 J/mol°C

now,

$\Delta \theta = \dfrac{\Delta U}{\Deta t}\times \dfrac{\Delta t}{n C_v}$

$\Delta \theta = 6.2\times 10^3 \times \dfrac{0.273}{1.7\times 20.93}$

$\Delta \theta = 47.57^{\circ} C$

the temperature change per compression stroke is equal to 47.57°C.

4 0

3 years ago

What is the average speed of a car that travels 40 mph for 1 hour and 60 mph in another hour?

svetoff [14.1K]

Average speed = (total distance covered) / (time to cover the distance)

-- Traveling at 40 mph for 1 hour, the distance covered is 40 miles.

-- Traveling at 60 mph for 1 hour, the distance covered is 60 miles.

-- Total distance covered = (40 miles) + (60 miles) = 100 miles

-- Total time = (1 hour) + (1 hour) = 2 hours

-- Average speed = (100 miles) / (2 hours)

<em>Average speed = 50 miles per hour</em>

6 0

3 years ago