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3 years ago

In physics, what is the positive and negative sign used for when applied to velocity and acceleration?

Physics

1 answer:

Orlov [11]3 years ago

8 0

Answer:

the positive and negative signs are used to show different directions of acceleration and velocity

Explanation:

for example, if a car was moving forward, you would usually express it with a positive sign. If the car started moving backwards, you would show that backwards motion with a negative sign.

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A centrifugal pump rotates at n˙ = 740 rpm. Suppose the pump has some swirl at the inlet (α1 = 10°) and exits at an angle of 35°

Blizzard [7]

Answer:

Net head = 380cm

bhp = 17.710kW

Explanation:

Angular velocity of centrifugal pump:

$w=\frac{2\pi n}{60}=\frac{2\pi (750)}{60}=78.54\frac{rad}{s}$

Normal velocity component at outlet of pump:

$V_{2,n}=\frac{V}{2\pi r_{2}b_{2}}=\frac{0.573}{2\pi (0.24)(0.162)}}=2.346\frac{m}{s}$

Tangential velocity component at exit of the pump:

$V_{2,t}=v_{2,n}tan\alpha _{2}=(2.346)tan(35)=1.643\frac{m}{s}$

Normal velocity component at inlet of pump:

$V_{1,n}=\frac{V}{2\pi r_{1} b_{1}}=\frac{0.573}{2\pi (0.12)(0.18)}=4.22\frac{m}{s}$

Tangential velocity component at inlet of the pump:

$V_{1,t}=v_{1,n}tan\alpha _{1}=(4.22)tan(0)=0\frac{m}{s}$

Equivalent head in centimetre of water column:

$H_{water}=H(\frac{rho_{air}}{rho_{water}})\\\\H_{water}=(\frac{w}{g} )(r_{2}V_{2,t}-r_{1}V_{1,t})(\frac{rho_{air}}{rho_{water}}) \\\\H_{water}=(\frac{78.54}{9.81})((0.24)(1.643)-(0.12)(0)})(\frac{1.2}{998})=38m=380cm$

Break horse power:

$bhp=rho_{water} gHV=rho_{water} g[(\frac{w}{g})(r_{2}V_{2,t}-r_{1}V_{1,t})]V\\\\bhp=(998)(9.81)[(\frac{78.54}{9.81})((0.24)(1.643)-(0.12)(0))](0.573)=17710W=17.710kW$

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3 years ago

3) If a ball launched at an angle of 10.0 degrees above horizontal from an initial height of 1.50 meters has a final horizontal

Irina-Kira [14]

Answer:

35.6 m

Explanation:

3 0

4 years ago

When you complete a job, but use more time and effort than is truly necessary, how have you worked?

MariettaO [177]

I believe the answers you're looking for is effectively but not efficiently. The reason its these choices is because although you finished the job, it was not done in the best way possible. So it was effective, but not efficient.

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3 years ago

if jane is trying to escape a dragon and runs 34m north then must run 38m east, what total distance does jane run

Andrej [43]

You would just add them, 34+38=72m

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3 years ago

You are a psychic when you tap into your other__% of your brain.

vladimir1956 [14]

20% would be probably right cuz 100% is total and 80+ what gives u 100 which is 20

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3 years ago