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3 years ago

A roller coaster starts from rest at the top ofan 18m hill.

Physics

1 answer:

KonstantinChe [14]3 years ago

7 0

Answer:

12.65 m/s

Explanation:

When friction is ignored, if the car travels from 18m hill to the bottom of the hill, afterwards it travels up to a 10m hill, then overall it has traveled a distance of 18 - 10 = 8 m vertically.

If the car starts from rest, then its potential energy is converted to kinetic energy:

$E_p = E_k$

$mgh = mv^2/2$

where m is the car mass and h is the vertical distance traveled, v is the car velocity at 10m hill

Let g = 10m/s^2. We can cancel m from both sides of the equation:

$gh = v^2/2$

$v^2 = 2gh = 2*10*8 = 160$

$v^2 = 160$

$v = \sqrt{160} = 12.65 m/s$

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A 200-loop coil of cross sectional area 8.5 cm2 lies in the plane of the paper. Directed out of the plane of the paper is a magn

Maslowich

Explanation:

It is given that,

Number of turns, N = 200

Area of cross section, A = 8.5 cm²

Magnetic field is directed out of the paper and is, B = 0.06 T

The magnetic field is out of the paper decreases to 0.02 T in 12 milliseconds. We need to find the direction of current induced. The induced emf is given by :

$\epsilon=-N\dfrac{d\phi}{dt}$

Since, $\epsilon=IR$

I is the induced current

$I=-\dfrac{N}{R}\dfrac{d\phi}{dt}$

According to Lenz's law, the direction of induced current is such that it always opposes the change in current that causes it.

Here, the field is directed out of the plane of the paper, this gives the induced current in counterclockwise direction.

5 0

3 years ago

A crowbar is being used with an actual mechanical advantage of 8. If the input force is 400 Newton’s on the 0.3 meter long end o

finlep [7]

Answer:

C. 3,200

Explanation:

MA= F out/ F in.

multiply F in on both sides to cancel it out so you can solve for F out.

Fin*MA=F out

400 * 8 = F out

3,200= F out

7 0

3 years ago

A professor designing a class demonstration connects a parallel-plate capacitor to a battery, so that the potential difference b

Lesechka [4]

Answer:

a) Q = 397.57 pC , Q = 3.18 104 pC , b) C = 1.157 10⁻¹⁰ F , V = 3.4375 V ,

c) U = 54.7 nJ , d) ΔU = 54 nJ,

Explanation:

a) The capacity of a capacitor is defined

C = Q / V

Q = C V

can also be calculated using geometry consideration

C = e or A / d

we reduce to the SI system

A = 25.0 cm² (1 m / 10² cm) 2 = 25.0 10⁻⁴ m²

d = 1.53 cm = 1.53 10⁻² m

we substitute

Q = eo A / d V

Q = 8.85 10⁻¹² 25 10⁻⁴ / 1.53 10⁻² 275

Q = 3.9757 10⁻¹⁰ C

let's reduce to pC

Q = 3.9757 10⁻¹⁰ C (10¹² pC / 1 C)

Q = 397.57 pC

when the capacitor is introduced into the water the dielectric constant is different

Q = k Q₀

Q = 80 397.57

Q = 3.18 104 pC

b) Find capacitance and voltage after submerged in water

C = k C₀

C = 80 8.85 10⁻¹² 25 10⁻⁴ / 1.53 10⁻²

C = 1.157 10⁻¹⁰ F

V = Vo / k

V = 275/80

V = 3.4375 V

c) The stored energy is

U = ½ C V²

U = ½, 85 10⁻¹² 25 10⁻⁴ / 1.53 10⁻² 275²

U = 5.47 10⁻⁸ J

let's reduce to nJ

109 nJ = 1 J

U = 54.7 nJ

d) energy after submerging

U = ½ (kCo) (Vo / k) 2

U = ½ Co Vo2 / k

U = U₀ / k

U = 54.7 / 80 nJ

U = 0.68375 nJ

the energy change is

ΔU = U₀ -U

ΔU = 54.7 - 0.687375

6 0

3 years ago

Use the velocity vs time graph to analyze the motion of the object.

arsen [322]

Explanation:

the object has constant velocity for 2 seconds and it get a constant accelration (2ms-2)

7 0

3 years ago

Two blocks connected by a rope of negligible mass are being dragged by a horizontal force (see figure below). Suppose F = 65.0 N

vovangra [49]

Refer to the diagram shown below.

g = 9.8 m/s², and air resistance is ignored.

For mass m₁:
The normal reaction is m₁g.
The resisting force is R₁ = μm₁g.

For mass m₂:
The normal reaction is m₂g.
The resisting force is R₂ = μm₂g.

Let a = the acceleration of the system.
Then
(m₁ + m₂)a = F - (R₁ + R₂)
(14+26 kg)*(a m/s²) = (65 N) - 0.098*(9.8 m/s²)*(14+26 kg)
40a = 65 - 38.416 = 26.584
a = 0.6646 m/s²

Answer: 0.665 m/s² (nearest thousandth)

7 0

3 years ago