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3 years ago

Is there any terminal identification mark for rheostat as positive, negative?

1 answer:

7 0

Rheostats are pure resistances with a provision to vary the resistance connected in the circuit with a moving contact. Resistance do not have polarities

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If a system requires 150 j of input work and produces 123 J of output work, whats its effiency

Yuki888 [10]

The effiency of a machine is

(output work or energy) / (input work or energy) .

For the system described in the question, that's

(123 J) / (150 J) = 0.82 = 82% .

4 0

3 years ago

What happens to the gravitational force between two objects if:

tiny-mole [99]

Answer:

See the answers below

Explanation:

This problem and its respective questions can be easily solved using Newton's law of universal gravitation. Which can be calculated by means of the following expression.

$F =G*\frac{m_{1}*m_{2}}{r^{2} }$

where:

G = it is the universal gravitation constant. = 6.673 x 10⁻¹¹ [N*m²/kg²]

m1 = mass of the first body [kg]

m2 = mass of the second body [kg]

r = distance among the bodies [m]

a. the mass of one is doubled?

When this happens we see that the force is increased twice as well, since the mass is in the numerator of the expression.

b. The masses of both are doubled?

If both masses are doubled the force is increased to four times its original value since the terms of the masses are in the numerator of the expression.

c. The distance between them is doubled?

In this case the force is decreased to half of its original value, since the distance is in the denominator of the expression of universal gravitation.

5 0

2 years ago

The New England Merchants Bank Building in Boston is 152 mm high. On windy days it sways with a frequency of 0.20 HzHz , and the

kkurt [141]

Answer:

The total distance, side to side, that the top of the building moves during such an oscillation = 31 cm

Explanation:

Let the total side to side motion be 2A. Where A is maximum acceleration.

Now, we know know that equation for maximum acceleration is;

A = α(max) / [(2πf)^(2)]

So 2A = 2[α(max) / [(2πf)^(2)] ]

α(max) = (0.025 x 9.81) while frequency(f) from the question is 0.2Hz.

Therefore 2A = 2 [(0.025 x 9.81) / [((2π(0.2)) ^(2)] ] = 2( 0.245 / 1.58) = 0.31m or 31cm

3 0

3 years ago

A boy reaches out of a window and tosses a ball straight up with a speed of 10 m/s. The ball is 20 m above the ground as he rele

kirill115 [55]

Explanation:

It is given that,

Speed of the ball, v = 10 m/s

Initial position of ball above ground, h = 20 m

(a) Let H is the maximum height reached by the ball. It can be calculated using the conservation of energy as :

$\dfrac{1}{2}mv^2=mgh'$

$h'=\dfrac{v^2}{2g}$

$h'=\dfrac{(10)^2}{2\times 9.8}$

h' = 5.1 m

The maximum height above ground,

H = 5.1 + 20

H = 25.1 meters

So, the maximum height reached by the ball is 25.1 meters.

(b) The ball's speed as it passes the window on its way down is same as the initial speed i.e. 10 m/s.

Hence, this is the required solution.

6 0

3 years ago

What are the units for the spring constant, k? A. newton meters B. newton seconds C. newtons/meter D. newtons/second E. newtons/

mr Goodwill [35]

Answer:

C. N/m (newtons/meter)

Explanation:

Since the equation for potential energy for a spring is PE = 1/2kx², after you know <em>k </em>and <em>x</em>, you will get an answer in Joules.

Please let me know if you want me to explain further!

Thanks!

5 0

3 years ago

Read 2 more answers