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Misha Larkins [42]
4 years ago
10

Need help on B please

Physics
1 answer:
Amanda [17]4 years ago
4 0

Answer:

The slowdown took 2.05 seconds and the roller coaster made a distance 20.5 during that time.

Explanation:

Start with the kinematic equation for velocity. Let v1 and v2 be the initial and the new velocity, respectively. Let s denote the distance made duringthe slowdown. Let m denote the mass of the roller coaster and "a" its acceleration (negative = deceleration). the equation is as follows:

v_2^2 = v_1^2 + 2ad\\F = ma\implies a = \frac{F}{m}\\v_2^2 = v_1^2 + 2\frac{F}{m}d

Let us first determine the distance made:

v_2^2 = v_1^2 + 2\frac{F}{m}d\implies\\d = \frac{v_2^2 - v_1^2}{2F}m = \frac{-320\frac{m^2}{s^2}}{2\cdot (-7023N) }\cdot 900kg = 20.5 m

The roller coaster made 20.5 meters during slowing down to 2 m/s. Now calculate the time this took.

v_2 = at+v_1 = \frac{F}{m}t + v_1\implies t = \frac{v_2-v_1}{F}m\\t = \frac{-16\frac{m}{s}}{-7023N}900kg = 2.05s

It took 2.05 seconds to achieve the slowdown from 18 to 2 m/s


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Can anyone help me learn Malus's law in optics?​
Harlamova29_29 [7]

Answer:

It is also called law of Malus,the law states that the intensity of a beam of plane-polarized light after passing through a rotatable polarizer varies as square of the cosine of the angle through which the polarizer is rotated from the position that gives maximum intensity expand.

Before u can know it u have to understand it, so go through it over and over again and u will get it.

8 0
3 years ago
Two parallel plates that are initially uncharged are separated by 1.7 mm, have only air between them, and each have surface area
yaroslaw [1]

Answer:

5.63\cdot 10^{-6} C

Explanation:

The capacitor of a parallel-plate capacitor is given by:

C=\epsilon_0 \frac{A}{d}

where

A is the area of each plate

d is the separation between the plates

\epsilon_0 is the vacuum permittivity

The energy stored in a capacitor instead is given by

U=\frac{1}{2}\frac{Q^2}{C}

where

Q is the charge stored in each plate

Substituting the expression we found for C inside the last formula,

U=\frac{1}{2}\frac{Q^2 d}{\epsilon_0 A}

And re-arranging it

Q=\sqrt{\frac{2U\epsilon_0 A}{d}}

Now if we substitute

d=1.7 mm=0.0017 m\\A=16 cm^2 = 16\cdot 10^{-4} m^2\\U = 1.9 J

We find the charge stored on the capacitor:

Q=\sqrt{\frac{2(1.9)(8.85\cdot 10^{-12})(16\cdot 10^{-4})}{0.0017}}=5.63\cdot 10^{-6} C

7 0
3 years ago
4. The blades on a fan have a frequency of 15 Hz.
vichka [17]

Answer:

a) 4500 cycles b) 0.0667s c) 6.67s

Explanation:

a) 15 Hz= 15 cycles/ s

   5 mins= 300s

   15 cycles/s * 300s= 4500 cycles

b) Period= 1/ frequency

   Period= 1/ 15 cycles/s

   Period= 0.0667s

c) Period * number of revolutions= time

  0.0667 * 100= 6.67s

6 0
3 years ago
The resistance of an electric heater is 50 Ω when connected to 120 V. How much energy does it use during 15 min of operation?
STALIN [3.7K]

Answer:

Explanation:

I = V/R = 120 V/ 50 Ω = 2.4 A

P = VI = 120(2.4) = 288 W = 288 J/s

288 J/s (15 min(60s / min)) = 259,200 J

or the electric company would charge for

288 W / (1000 W/kW)•(15/60) hr = 0.072 kW•hr

At $0.20 / kW•hr, that would be under 1½ cents

7 0
3 years ago
Soap bubbles can display impressive colors, which are the result of the enhanced reflection of light of particular wavelengths f
Bogdan [553]

Answer:

the minimum wall thickness that will enhance the reflection of light is 146.9 nm

Explanation:

Given the data in the question;

At the first interface, a phase shift occurs as the incident light is in air that has less refractive index compare to the thin film of soap bubble.

At the second interface, no shift occurs,

condition for constructive interference;

t = ( m + 1/2) × λ/2n

where m = 0, 1, 2, 3 . . . . . .

now, the condition for the constructive interference;

t = mλ/2n

where t is the thickness of the soap bubble,  λ is the wavelength of light and n is the refractive index of soap bubble.

so the minimum thickness of the film which will enhance reflection of light will be;

t_{min =  ( m + 1/2) × λ/2n

we substitute

t_{min =  ( 0 + 1/2) × 711 /2(1.21)

t_{min = 0.5 × 711/2.42

t_{min = 0.5 × 293.80165

t_{min = 146.9 nm

Therefore,  the minimum wall thickness that will enhance the reflection of light is 146.9 nm

8 0
3 years ago
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