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Lunna [17]
3 years ago
8

Which of these is an example of a chemical change?

Physics
2 answers:
nadya68 [22]3 years ago
6 0
1 - fireworks exploding
lora16 [44]3 years ago
3 0

Answer:

Fireworks Exploding

Explanation:

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You have a 2m long wire which you will make into a thin coil with N loops to generate a magnetic field of 3mT when the current i
Anni [7]

Answer:

<em>radius of the loop =  7.9 mm</em>

<em>number of turns N ≅ 399 turns</em>

Explanation:

length of wire L= 2 m

field strength B = 3 mT = 0.003 T

current I = 12 A

recall that field strength B = μnI

where n is the turn per unit length

vacuum permeability μ  = 4\pi *10^{-7}  T-m/A = 1.256 x 10^-6 T-m/A

imputing values, we have

0.003 = 1.256 x 10^−6 x n x 12

0.003 = 1.507 x 10^-5 x n

n = 199.07 turns per unit length

for a length of 2 m,

number of loop N = 2 x 199.07 = 398.14 ≅ <em>399 turns</em>

since  there are approximately 399 turns formed by the 2 m length of wire, it means that each loop is formed by 2/399 = 0.005 m of the wire.

this length is also equal to the circumference of each loop

the circumference of each loop = 2\pi r

0.005 = 2 x 3.142 x r

r = 0.005/6.284 = 7.9*10^{-4} m = 0.0079 m =<em> 7.9 mm</em>

8 0
3 years ago
A 35.0-kg dolphin decelerates from 12.0 to 7.50 m/s in 2.30 s to join another dolphin in play. What average force was exerted to
Stels [109]

Answer:

68.5N

Explanation:

When the dolphin decelerates from 12m/s to 7.5 m/s within 2.3s. Then its acceleration is:

a = \frac{\Delta v}{\Delta t} = \frac{7.5 - 12}{2.3} = -1.96 m/s^2

The dolphin has a mass of 35kg, according to the Newton's 2nd law, the force exerted on it must be:

F = ma = 35*1.96 = 68.5 N

6 0
3 years ago
A car travels at 40 km/hr for two hours and 55 km/hr for two hours. How far does the car travel? What is the average velocity?
KiRa [710]

Driving at 40 km/h for 2 h contributes a distance of 80 km, while driving at 55 km/h for 2h contributes 110 km, giving a total of 190 km traveled. If the car is traveling in the same direction throughout this ordeal, then the average velocity is

\bar v=\dfrac{190\,\mathrm{km}}{4\,\mathrm h}=47.5\,\dfrac{\mathrm{km}}{\mathrm h}

6 0
3 years ago
A chair of mass 14.0 kg is sitting on the horizontal floor; the floor is not frictionless. You push on the chair with a force F
Flura [38]

Answer: a) 110.3N b) 0.39

Explanation:

a) The normal reaction force acts in the vertical direction opposite the weight of the object(check attachment for diagram).

Since the object is inclined at 38° to the horizontal, the weight (W) will become Wcos38°.

Since the body is not moving vertically, its acceleration I'm the vertical direction will be zero.

According to newton's first law,

F = ma

Since we have two forces acting in the vertical direction, we will take their sum

R - Wcos38° = m(0)...1

Note that normal reaction (R) is acting in the positive y direction while the weight is in the negative y direction.

From 1,

R - Wcos38° = 0

R = Wcos38°

R = mg cos38°

R = 14×10×cos38°

R = 140cos38°

R = 110.3N

b) For the coefficient of friction,

Taking the sum of forces along x -direction

Fm - Ff = ma

Since a = 0(constant velocity)

Fm = Ff  = 43N

Note that Fm is the moving force (force that causes the body to move)

Ff = frictional force

Since Ff = nR

n is the coefficient of friction

43 = n× 110.3

n = 43/110.3

n = 0.39

Coefficient of kinetic friction = 0.39

8 0
3 years ago
A car, with an initial position of x=83.2 meters, undergo as a displacement of -153.0 meters.
pickupchik [31]

Answer:

The final position is -69.8 m

Explanation:

Recall that displacement is defined as:

displacement=x_f-x_i

where x_f represents the final position, and x_i the initial position of the object (in our case 83.2 m). Since we also know the displacement (-153 m), we can solve the equation for the final position:

displacement=x_f-x_i\\-153=x_f-83.2\\-153+83.2=x_y\\x_f=-69.8\,\,m

8 0
3 years ago
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