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lukranit [14]
3 years ago
13

A car is traveling at 20 meters/second and is brought to rest by applying brakes over a period of 4 seconds. What is its average

acceleration over this time interval?
Physics
2 answers:
frez [133]3 years ago
8 0
 (u) = 20 m/s 
(v) = 0 m/s 
<span> (t) = 4 s 
</span>
<span>0 = 20 + a(4) 

</span><span>4 x a = -20 
</span>
so, the answer is <span>-5 m/s^2. or -5 meter per second</span>
Feliz [49]3 years ago
8 0
The answer is -5 m/s^2. or -5 meter per second
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What is the intensity in W/m2 of a laser beam used to burn away cancerous tissue that, when 85.0% absorbed, puts 470 J of energy
Advocard [28]

Answer:

26036485.6433 W/m²

Explanation:

E= Energy = 470 J

t = Time = 4 seconds

d = Diameter = 2.6 mm

Power is given by

P=\dfrac{E}{t}

Intensity is given by

I=\dfrac{P}{\pi r^2}\\\Rightarrow 0.85I=\dfrac{E}{t\dfrac{\pi}{4} d^2}\\\Rightarrow I=\dfrac{470}{0.85\times 4\times \dfrac{\pi}{4}\times (2.6\times 10^{-3})^2}\\\Rightarrow I=26036485.6433\ W/m^2

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3 years ago
The structural diversity of carbon-based molecules is determined by which properties?
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Explanation:

The structural diversity of carbon-based molecules is determined by following properties:

1. the ability of those bonds to rotate freely,

2.the ability of carbon to form four covalent bonds,

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3 years ago
A skateboarder flies horizontally off a cement planter. After 3 seconds the skateboarder lands on the ground with a final veloci
evablogger [386]

Given the time, the final velocity and the acceleration, we can calculate the initial velocity using the kinematic equation A:

v = v_o + a \Delta t

A skateboarder flies horizontally off a cement planter. After a time of 3 seconds (Δt), he lands with a final velocity (v) of −4.5 m/s. Assuming the acceleration is -9.8 m/s² (a), we can calculate the initial velocity of the skateboarder (v₀) using the kinematic equation A.

v = v_o + a \Delta t\\\\v_o = v - a \Delta t = (-4.5 m/s) - (-9.8 m/s^{2} ) \times 3 s = 24.9 m/s

Given the time, the final velocity and the acceleration, we can calculate the initial velocity using the kinematic equation A:

v = v_o + a \Delta t

Learn more: brainly.com/question/4434106

3 0
3 years ago
A fuse in an electric circuit is a wire that is designed to melt, and thereby open the circuit, if the current exceeds a predete
zmey [24]

Answer:

The diameter of wire should be 4.04 \times 10^{-4} m

Explanation:

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Current density J = 500 \times 10^{4} \frac{A}{m^{2} }

Current I = 0.64 A

From the formula of current density,

  J = \frac{I}{A}

Where A = area of cylindrical wire = \pi r^{2}

  \pi r^{2} = \frac{I}{J}

  r^{2} = \frac{I}{\pi J }

   r = \sqrt{\frac{0.64}{3.14 \times 500 \times 10^{4} } }

   r = 2.02 \times 10^{-4}m

For finding the diameter of wire,

   d = 2r

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Therefore, the diameter of wire should be 4.04 \times 10^{-4} m

8 0
3 years ago
According to Newton's law of cooling, the rate at which an object's temperature changes is directly proportional to the differen
Kryger [21]

Answer:

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Introducing the constant of proportionality

dT(t)/dt = k[T5 - T(t)]

which is the desired differential equation

4 0
3 years ago
Read 2 more answers
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