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4 years ago

Balanced- Forces acting on an object are balanced if the ....

Physics

1 answer:

choli [55]4 years ago

7 0

Answer:

there is an equal and opposite force
moving

Explanation:

When balanced forces act on an <em>object at rest</em>, the object will not move. If you push against a wall, the wall pushes back with an equal but opposite force. Neither you nor the wall will move. Forces that cause a change in the motion of an object are unbalanced forces.

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Air expands isentropically from 2.2 MPa and 77°C to 0.4 MPa. Calculate the ratio of the initial to the final speed of sound.

djyliett [7]

Answer:

The ratio of initial to final speed of sound is given as 1.28.

Explanation:

As per the thermodynamic relation of isentropic expansion

$\frac{T_2}{T_1}=(\frac{P_2}{P_1})^{\frac{k-1}{k}}$

Here

$P_1$ is the pressure at point 1 which is given as 2.2 MPa
$T_1$ is the temperature at point 1 which is given as 77 °C or 273+77=350K

$P_2$ is the pressure at point 1 which is given as 0.4 MPa
$T_2$ is the temperature at point 2 which is to be calculated
k is the ratio of specific heats given as 1.4

Substituting values in the equation

$\frac{T_2}{350}=(\frac{0.4}{2.2})^{\frac{1.4-1}{1.4}}\\\frac{T_2}{350}=(0.18)^{0.2857}\\T_2=(0.18)^{0.2857} \times 350 \\T_2=0.61266 \times 350\\T_2=214.43 K$

As speed of sound c is given as

$c=\sqrt{kRT}$

for initial to final values it is given as

$\frac{c_i}{c_f}=\frac{\sqrt{k_1R_1T_1}}{\sqrt{k_2R_2T_2}}$

As values of k and R is constant so the ratio is given as

$\frac{c_i}{c_f}=\sqrt{\frac{T_1}{T_2}}$

Substituting values give

$\frac{c_i}{c_f}=\sqrt{\frac{350}{214.43}}\\\frac{c_i}{c_f}=\sqrt{1.63}}\\\frac{c_i}{c_f}=1.277 \approx 1.28$

So the ratio of initial to final speed of sound is 1.28.

5 0

3 years ago

When resistance is decreased in a circuit, current will _________.

Mars2501 [29]

The answer is A. Increase

The formula is <span>Voltage = Resistance X Current

Lets say the voltage is 10 and the resistence is 5

10 = 5 x current
Current = 2

Now, lets decrease the resistence from 5 to 2

10 = 2 x Current
Current = 5

The current increases
</span>

8 0

3 years ago

The magnitude of the voltage induced in a conductor moving through a stationary magnetic field depends on the _______ and the __

Virty [35]

The correct answer is: Option (D) length, speed

Explanation:

According to Faraday's Law of Induction:

ξ = Blv

Where,

ξ = Emf Induced

B = Magnetic Induction

l = Length of the conductor

v = Speed of the conductor.

As you can see that ξ (Emf/voltage induction) is directly proportional to the length and the speed of the conductor. Therefore, the correct answer will be Option (D) Length, Speed

3 0

3 years ago

Read 2 more answers

Assume that the upward direction is positive and the downward direction is negative. What is the ball's velocity (in m/s) when i

LenaWriter [7]

The given question is incomplete. The complete question is as follows.

You throw a ball vertically upward, and as it leaves your hand, its speed is 26.0 m/s.

(a) How high (in m) does it rise above the level where it leaves your hand?

(b) How long (in s) does it take to reach its highest point?

(c) How long (in s) does the ball take to return to the level where it left your hand after it reaches its highest point?

(d) Assume that the upward direction is positive and the downward direction is negative. What is the ball's velocity (in m/s) when it returns to the level where it left your hand? (Indicate the direction with the sign of your answer.)

Explanation:

(a) For maximum height, the formula will be as follows.

$v^{2} = u^{2} + 2as$

a = $v^{2} - 2gh$

or, h = $\frac{v^{2}}{2g}$

= $\frac{(26)^{2}}{2 \times 9.8}$

= $\frac{676}{19.6}$

= 34.5 m/s

Hence, it rises 34.5 m/s above the level where it leaves your hand.

(b) Time to reach maximum height is as follows.

v = u + at

or, v - gt = 0

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

= $\frac{26}{10}$

= 2.6 sec

Therefore, it will take 2.6 sec to reach its highest point.

(c) Time taken by the ball to ascent is equal to the time it has taken to descent.

Therefore, time taken by the ball to return to the level where it left your hand after it reaches its highest point? is also 2.6 sec.

(d) Speed of the ball will be 26 m/s in the downward direction. Hence, the velocity will be -26 m/s.

3 0

3 years ago

How does the jet stream affect the movement of air masses

ryzh [129]

Answer:

See the explanation below.

Explanation:

Jet streams are defined as the fast flowing meandering air currents in the atmosphere, they generally flow around ten kilometers from above the Earth's surface and form at the boundaries of two air masses which have significant temperature difference within them, greater the temperature difference more significant and fast flowing will be the jet streams. Jet streams have a key role in determining the weather of given region as it separates warmer air mass with the colder air mass and hence move the weather system to new areas and sometimes it even stops at any particular place therefore determining or affecting the weather condition of the region. Depending upon seasons and other factors such as position of sun these jet streams also shift their patterns, for example, Weather and climatic condition of United Kingdom is largely affected by the movement of these Jet streams.

5 0

4 years ago