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3 years ago

10 POINT PLS HELP

1 answer:

5 0

Answer: A heat engine cannot be 100% efficient because, according to the law, energy added as heat is always greater than energy removed as heat.

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3 years ago

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What action happens if the moon spins on its axis like a top

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3 years ago

If there is a 25 [lbs] of force acting on a 5 [lbs] of mass, what is the acceleration of that mass?

mihalych1998 [28]

Answer:

f = 25 lbs

m = 5 lbs

a =?

f = ma

25 = 5 a( divide both sides by 5)

a = 5(lbs)

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3 years ago

A 2.00 kg block hangs from a spring balance calibrated in Newtons that is attached to the ceiling of an elevator.(a) What does t

tresset_1 [31]

Answer:

Part a)

$Reading = 2.00 kg$

Part b)

$Reading = 2.00 kg$

Part c)

$Reading = 4.04 kg$

Part d)

from t = 0 to t = 4.9 s

so the reading of the scale will be same as that of weight of the block

Then its speed will reduce to zero in next 3.2 s

from t = 4.9 to t = 8.1 s

The reading of the scale will be less than the actual mass

Explanation:

Part a)

When elevator is ascending with constant speed then we will have

$F_{net} = 0$

$T - mg = 0$

$T = mg$

So it will read same as that of the mass

$Reading = 2.00 kg$

Part b)

When elevator is decending with constant speed then we will have

$F_{net} = 0$

$T - mg = 0$

$T = mg$

So it will read same as that of the mass

$Reading = 2.00 kg$

Part c)

When elevator is ascending with constant speed 39 m/s and acceleration 10 m/s/s then we will have

$F_{net} = ma$

$T - mg = ma$

$T = mg + ma$

Reading is given as

$Reading = \frac{mg + ma}{g}$

$Reading = 2.00\frac{9.81 + 10}{9.81}$

$Reading = 4.04 kg$

Part d)

Here the speed of the elevator is constant initially

from t = 0 to t = 4.9 s

so the reading of the scale will be same as that of weight of the block

Then its speed will reduce to zero in next 3.2 s

from t = 4.9 to t = 8.1 s

The reading of the scale will be less than the actual mass

3 0

3 years ago

A high speed train is traveling at a speed of 44.7 m/s when the engineer sounds the 415 Hz warning horn. The speed of sound is 3

il63 [147K]

Answer:

Explanation:

Speed of the source of sound = v = 44.7 m/s

Speed of sound = V = 343 m/s

a) Apparent frequency as the train approaches = f = [V /(V -v) ] × f

= [343 / (343 - 44.7) ] × 415 = 477.18 Hz

Wave length = λ = v / f = 343 / 477.18 = 0.719 m

b) Frequency heard as the train leaves = f ' = [V / ( V + v) ] f

= [343 / { 343 + 44.7 ) ] x 415

= 367.2 Hz

Wavelength when leaving = v / f = 343 / 367.2 = 0.934 m

8 0

3 years ago