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2 years ago

dado los vectores a=3.5 b=4 c=6.5 , si se sabe que a+b+c=0 (resultante) cual es el angulo formado por A y B?

1 answer:

6 0

cos(A) = (b2 + c2 − a2) / 2bc = (16+6.5^2-3.5^2)/(2*4*6.5) = 0.88461538 so A = cos−1 (0.88461538) = 27.79 Deg cos(B) = (c2 + a2 − b2)/2ca = (3.5^2+6.5^2-16)/(2*3.5*6.5) = 0.84615385 so B = cos−1 (0.84615385) = 32.2 Deg

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A disk drive plugged into a 120V outlet operates on a voltage of 12V . The transformer that powers the disk drive has 125 turns

Serga [27]

Answer:

(A-) Number of turns in secondary coil will be less than 125.

(B-) EXPLAIN- The voltage is to be lowered. The voltage will be reduced from 120 to 9 volts. As a result, a step down transformer will be used, indicating that the secondary coil's number of turns would be less than 125.

(C-) The number of turns on the secondary coil is 12.5

Explanation:

STEP DOWN TRANSFORMER - A step-down transformer transforms high voltage (HV) and low current from the transformer's primary side to low voltage (LV) and high current on the secondary side. A phase down transformer is the opposite of this.

In electrical networks and transmission lines, a step-down transformer can be used in a number of ways.

Step down transformer formula-

$V_s=\frac{N_s\times V_p}{N_p}$

We are given with the -

Primary voltage $V_p$ = 120V

Secondary voltage $Vs=12V$

Number of primary turns $N_p=125$

To calculate the number of turns on the secondary coil -

Since , the transformer ratio is given as -

$\frac{N_s}{N_p} =\frac{V_s}{V_p}$

So, the number of turns on the secondary coil is - $N_s=N_p\times\frac{V_p}{V_s}$

Putting , the given values -:

$125\times\frac{12}{120}$

= 12.5

Therefore , the number of turns on secondary coil is 12.5 .

6 0

2 years ago

A bowling ball moves 18 meters every 2 seconds down the lane at a bowling alley. What is the speed of the bowling ball?

Strike441 [17]

Answer:

9m/s

Explanation:

18/2 = 9m/s

3 0

2 years ago

A positive point charge Q is fixed on a very large horizontal frictionless tabletop. A second positive point charge q is release

Scilla [17]

Answer:

(A) As it moves farther and farther from Q, its speed will keep increasing.

Explanation:

When a positive charge Q is fixed on a horizontal frictionless tabletop and a second charge q is released near to it then according to the Coulombs law the force acting on it decreases with the square of the distance between them.

Mathematically:

$F=\frac{1}{4\pi.\epsilon_0} \times \frac{Q.q}{r^2}$

where:

r = distance between the charges

$\epsilon_0=$ permittivity of free space

By the Newtons' second law of motion if the we know that the acceleration is directly proportional to the force applied. So as the distance between the charges increases the its acceleration also decreases therefore now the charge feels less acceleration but still continues to accelerate with a fading magnitude.

7 0

2 years ago

A team of bicyclists are on bikes that require 512 J of work to ride. It takes 432 J of work for the bike to turn the gears. Wha

Alja [10]

Answer:

84.4 %

Explanation:

Mechanical efficiency = output work/input work × 100 %

output work = 432 J of work for the bike to turn the gears

input work = 512 J of work to ride.

Mechanical efficiency = 432 J/512 J × 100 %

= 0.844 × 100%

= 84.4 %

8 0

2 years ago

Suzy drops a rock from the roof of her house. Mary sees the rock pass her 2.7 m tall window in 0.129 sec. From how high above th

vladimir1956 [14]

Answer:

h = 22.35 m

Explanation:

given,

initial speed of the rock,u = 0 m/s

length of the window,l = 2.7 m

time taken to cross the window,t = 0.129 s

Speed of the rock when it crosses the window

$v = \dfrac{l}{t}$

$v = \dfrac{2.7}{0.129}$

v = 20.93 m/s

height of the building above the window

using equation of motion

v² = u² + 2 g h

20.93² = 0² + 2 x 9.8 x h

h = 22.35 m

Hence, the height of the building above the top of window is equal to h = 22.35 m

8 0

2 years ago