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3 years ago

8

A car from the beginning was traveling at 27.8m/s when he stepped on the brakes and stopped. According to the DMV, this would le

ave a skid mark of 60m. What is his acceleration?

1 answer:

Yuliya22 [10]3 years ago

3 0

Answer:

-6.44 m/s²

Explanation:

Given:

Δx = 60 m

v₀ = 27.8 m/s

v = 0 m/s

Find: a

v² = v₀² + 2aΔx

(0 m/s)² = (27.8 m/s)² + 2a (60 m)

a = -6.44 m/s²

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A current I flows down a wire of radius a.

Helga [31]

Answer:

(a) $K = \frac{I}{2\pi a}$

(b) $J = \frac{I}{2\pi as}$

Explanation:

(a) The surface current density of a conductor is the current flowing per unit length of the conductor.

$K = \frac{dI}{dL}$

Considering a wire, the current is uniformly distributed over the circumferenece of the wire.

$dL = 2\pi r$

The radius of the wire = a

$dL = 2\pi a$

The surface current density $K = \frac{I}{2\pi a}$

(b) The current density is inversely proportional

$J \alpha s^{-1}$

$J = \frac{k}{s}$ ......(1)

k is the constant of proportionality

$I = \int\limits {J} \, dS$

$I = J \int\limits \, dS$ ........(2)

substituting (1) into (2)

$I = \frac{k}{s} \int\limits\, dS$

$I = k \int\limits^a_0 \frac{1}{s} {s} \, dS$

$I = 2\pi k\int\limits\, dS$

$I = 2\pi ka$

$k = \frac{I}{2\pi a}$

substitute $J = \frac{k}{s}$

$J = \frac{I}{2\pi as}$

7 0

2 years ago

What two variables is acceleration dependent on?

Vaselesa [24]

The correct answer to this qustion is velocity and time

7 0

3 years ago

A 269-turn solenoid is 102 cm long and has a radius of 2.3 cm. It carries a current of 3.9 A. What is the magnetic field inside

RUDIKE [14]

Answer:

Magnitude of the magnetic field inside the solenoid near its centre is 1.293 x 10⁻³ T

Explanation:

Given;

number of turns of solenoid, N = 269 turn

length of the solenoid, L = 102 cm = 1.02 m

radius of the solenoid, r = 2.3 cm = 0.023 m

current in the solenoid, I = 3.9 A

Magnitude of the magnetic field inside the solenoid near its centre is calculated as;

$B = \frac{\mu_o NI}{l} \\\\$

Where;

μ₀ is permeability of free space = 4π x 10⁻⁷ m/A

$B = \frac{4\pi*10^{-7} *269*3.9}{1.02} \\\\B = 1.293 *10^{-3} \ T$

Therefore, magnitude of the magnetic field inside the solenoid near its centre is 1.293 x 10⁻³ T

8 0

3 years ago

A 0.450 kg soccer ball has a kinetic energy of 119 J.

Anastaziya [24]

Answer:

V is approximately = 23m/s

Explanation:

Kinetic energy = ½ mv²

Where m= mass = 0.450kg

V= velocity =?

K. E = 119J

Therefore

K. E = ½ mv²

Input values given

119= ½ × 0.450 × v²

Multiply both sides by 2

119 ×2 = 2 × 1/2 × 0.450 × v²

238= 0.450v²

Divide both sides by 0.450

238/0.450 = 0.450v²/0.450

v² = 528.89

Square root both sides

Sq rt v² = sq rt 528.89

V = 22.998m/s

V is approximately = 23m/s

I hope this was helpful, please rate as brainliest

8 0

3 years ago

What describes how fast an object is moving and in what direction

Mashcka [7]

Speed is a description of how fast an object moves; velocity is how fast and in what direction it moves. In physics, velocity is speed in a given direction. When we say a car travels at 60 km/h, we are specifying its speed.

6 0

3 years ago

Read 2 more answers